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  • richardmitnick 11:00 am on May 15, 2020 Permalink | Reply
    Tags: "Seeing the Universe Through New Lenses", , , , , Dark Energy, , ,   

    From Lawrence Berkeley National Lab: “Seeing the Universe Through New Lenses” 


    From Lawrence Berkeley National Lab

    May 14, 2020
    Glenn Roberts Jr.
    (510) 520-0843
    geroberts@lbl.gov

    Images collected for dark energy telescope project reveal hundreds of new gravitational lens candidates.

    1
    This Hubble Space Telescope image shows a gravitational lens (center) that was first identified as a lens candidate with the assistance of a neural network that processed ground-based space images. The lens is artificially colorized and circled in this image. (Credit: Hubble Space Telescope)

    Like crystal balls for the universe’s deeper mysteries, galaxies and other massive space objects can serve as lenses to more distant objects and phenomena along the same path, bending light in revelatory ways.

    Gravitational lensing was first theorized by Albert Einstein more than 100 years ago to describe how light bends when it travels past massive objects like galaxies and galaxy clusters.

    These lensing effects are typically described as weak or strong, and the strength of a lens relates to an object’s position and mass and distance from the light source that is lensed. Strong lenses can have 100 billion times more mass than our sun, causing light from more distant objects in the same path to magnify and split, for example, into multiple images, or to appear as dramatic arcs or rings.

    The major limitation of strong gravitational lenses has been their scarcity, with only several hundred confirmed since the first observation in 1979, but that’s changing … and fast.

    A new study by an international team of scientists revealed 335 new strong lensing candidates based on a deep dive into data collected for a U.S. Department of Energy-supported telescope project in Arizona called the Dark Energy Spectroscopic Instrument (DESI).

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory started in 2018

    NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    The study, published May 7 in The Astrophysical Journal, benefited from the winning machine-learning algorithm in an international science competition.

    “Finding these objects is like finding telescopes that are the size of a galaxy,” said David Schlegel, a senior scientist in Lawrence Berkeley National Laboratory’s (Berkeley Lab’s) Physics Division who participated in the study. “They’re powerful probes of dark matter and dark energy.”

    These newly discovered gravitational lens candidates could provide specific markers for precisely measuring distances to galaxies in the ancient universe if supernovae are observed and precisely tracked and measured via these lenses, for example.

    Strong lenses also provide a powerful window into the unseen universe of dark matter, which makes up about 85 percent of the matter in the universe, as most of the mass responsible for lensing effects is thought to be Dark Matter. Dark Matter and the accelerating expansion of the universe, driven by Dark Energy, are among the biggest mysteries that physicists are working to solve.

    In the latest study, researchers enlisted Cori, a supercomputer at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), to automatically compare imaging data from the Dark Energy Camera Legacy Survey (DECaLS) – one of three surveys conducted in preparation for DESI – with a training sample of 423 known lenses and 9,451 non-lenses.

    NERSC Cray Cori II supercomputer at NERSC at LBNL, named after Gerty Cori, the first American woman to win a Nobel Prize in science

    The researchers grouped the candidate strong lenses into three categories based on the likelihood that they are, in fact, lenses: Grade A for the 60 candidates that are most likely to be lenses, Grade B for the 105 candidates with less pronounced features, and Grade C for the 176 candidate lenses that have fainter and smaller lensing features than those in the other two categories.

    Xiaosheng Huang, the study’s lead author, noted that the team already succeeded in winning time on the Hubble Space Telescope to confirm some of the most promising lensing candidates revealed in the study, with observing time on the Hubble that began in late 2019.

    “The Hubble Space Telescope can see the fine details without the blurring effects of Earth’s atmosphere,” Huang said.

    __________________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova


    __________________________________________
    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    __________________________________________

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    LBNL campus

    LBNL Molecular Foundry

    Bringing Science Solutions to the World
    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

    A U.S. Department of Energy National Laboratory Operated by the University of California.

    University of California Seal

     
    • Barbarina Zwicky 6:10 pm on May 15, 2020 Permalink | Reply

      Rubin has been a constant nuisance to my father’s legacy in regard to Dark Matter and often took false credit for its discovery, crowning herself as “Discoverer of Dark Matter.” The naming of LSST after Rubin, is an undeserved honor for this celebrated plagiarist.

      Vera Rubin was celebrated in the press and by several institutions for her work in specific in regard to Dark Matter, my father’s discovery, as well as responsible for the roughshod over my father, his memory, and credit for his original work, by falsely assigning that credit to herself in numerous incidents involving the media and even nomenclature of her lecture: “I left Vassar and Found Dark Matter.” I consider Vera Rubin a person who attached herself to my father’s original work in parasitic forced credit, repeatedly advanced this unethical agenda and academic dishonesty, crowning herself as “Discoverer of Dark Matter,” the published achievement of another. Rubin’s dictates of conscience revealed a failed ethical compass as she assigned herself credit for my father’s methodology and that of others in the sciences in regard to the mathematical calculations in regard to the rotational speeds of galaxies, as well as claiming to be the “Discoverer of Dark Matter.” Vera Rubin was a constant unwanted barnacle that was attached to my father’s discovery, Dark Matter. The advancement of bringing the gravitational phenomena of Dark Matter to light and into the modern consciousness of physicists worldwide would have regardless been unsealed from the echoes of my father’s original work in 1933. Fritz Zwicky: “I consequently engaged in the application of certain simple general principles of morphological research, and in particular the method of Directed Intuition that would allow me to predict and visualize the existence of as yet unknown cosmic objects and phenomena.” Fritz Zwicky’s eidolon was realized from the results of his observations published in “Die Rotverschiebung von extragalaktischen Nebeln”, Helv. Phys. Acta 6, 110-127 (1933). English translation Johannes Nicolai Meyling – Barbarina Exita Zwicky (2013). Fritz Zwicky discovered Dark Matter and coined, dunkle (kalte) Materie (cold dark matter) in his 1933 article referenced above. The Mass-Radial Acceleration Discrepancy by measuring the speeds of galaxies in the Coma Cluster originated with Fritz Zwicky, not Rubin, as using the more challenging methodology of the virial theorem, by relating the total average kinetic energy and the total average potential energy of the galaxies of the Coma Cluster. He advanced that the virial for a pair of orbiting masses is zero, and used the principle of superposition to craft the argument to a system of interacting mass points. Zwicky then used the position and velocity measurements to determine the mass of the galaxy cluster. The LSST will endeavor to discover Dark Matter and should not be renamed at all, and certainly not after Vera Rubin, who plagiarized discovery in regard to Dark Matter, without acknowledgment of its provenance and pioneer, Fritz Zwicky, and deprives rightful illumination to the Father of Dark Matter. It will highlight this interloper and celebrate this forced credit from the rightful person due, Fritz Zwicky, by memorializing the name of LSST after this faux “pioneer” and self-proclaimed “Discoverer of Dark Matter.”

      Like

  • richardmitnick 12:14 pm on April 23, 2020 Permalink | Reply
    Tags: "Detailed Cosmic Map to Reveal Dark Energy's Sway", , , , , Dark Energy, , ,   

    From The Kavli Foundation: “Detailed Cosmic Map to Reveal Dark Energy’s Sway” 

    KavliFoundation

    From The Kavli Foundation

    03/25/2020 [Just now in social media.]

    Media Contact

    Katie McKissick
    The Kavli Foundation
    (424) 353-8800
    kmckissick@kavlifoundation.org

    By Adam Hadhazy

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory started in 2018

    .

    3
    DESI, a bold celestial mapmaking effort, will help unravel the mystery of the universe’s accelerating expansion rate. Here, star trails take shape around the 14-story Mayall Telescope dome in this long-exposure image. The Dark Energy Spectroscopic Instrument resides within this dome. (Credit: P. Marenfeld and NOAO/AURA/NSF)​

    NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    Compared to cosmic mapmakers, terrestrial cartographers have it relatively easy. Map generation here on Earth generally deals with just two dimensions—the latitude and longitude of where portions of landmasses and oceans all stitch together, forming the surface of our planet.

    Out in space, though, the third dimension reigns.

    After all, space is not called “space” for nothing; the sheer amount of volume out there through which galaxies are strewn is staggering. In order to understand the universe’s development, researchers need to chart its great expanse by accurately gauging distances between clusters of galaxies. Like on Earth, where the location of landmasses today speaks to eons of geophysical evolution, continental drift, tectonics, and so on, so, too, do the locations of galaxies speak to the dynamic history of the cosmos.

    The geo-analogy is only so apt, however, because looking deep into space is also looking deep into time; the farther away something is, the farther back in the universe’s chronology we are glimpsing it. As a result, not only does a cosmic map capture where things are in relation to each other, it also captures when things are in relation to each other.

    Tackling this time-and-space challenge anew is the Dark Energy Spectroscopic Instrument (DESI). Now mounted on a telescope in Arizona, DESI will soon begin making the most detailed 3D map of the universe to date. More than 500 researchers, hailing from 75 institutions in 13 countries, are part of the DESI project, including researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint project of Stanford University and the SLAC National Accelerator Laboratory.




    Numbers-wise, over a five-year observing run that starts in 2020, DESI will look at a third of the sky, accurately mapping the distances to approximately 35 million galaxies and 2.4 million quasars. (Quasars are ultra-bright galaxies whose central supermassive black holes are gorging on matter.) That tidy galactic sum represents about 20 times more objects than any previous such effort.

    “We’ll know in 3D space where the galaxies are with DESI, and with that, we can look at how galaxies are arranged in the universe,” says Aaron Roodman, who worked on image analysis elements of the Guiding, Focusing and Alignment (GFA) subsystem for DESI. Roodman is a professor and chair of the Particle Physics & Astrophysics department at SLAC and a member of KIPAC.

    DESI’s mapmaking is not for astronaut traveling purposes, of course. (Heck, we humans will be lucky if we get back to the Moon in the next decade, after a 50-year hiatus.) Instead, the goal for DESI is to help us better understand the history and eventual fate of the universe by nailing down the workings of Dark Energy. Right there in DESI’s name, “dark energy” refers to an enigmatic force that theoretically comprises most of reality.

    “This thing we call dark energy makes up 70 of the matter-energy density of the universe, but we don’t know what it is,” says Roodman.

    Dark energy’s presence looms large, invoked to explain why the universe’s rate of acceleration is increasing over history. The overall situation is thus: Matter, the substance that comprises everything we deal with every day, registers at just 5% of the total contents of the cosmos. A second enigmatic ingredient, Dark Matter, takes up the remaining 25% percent (once dark energy’s dominance – clocking in at nearly 70% – is counted). Dark matter interacts with normal matter only through gravity, so far as we know, acting like a universe-spanning scaffold upon which normal matter is hung. That normal matter interacts with itself through the forces of nature to give us galaxies, stars, planets, elephants, paramecia, you name it.

    Researchers want to bring this overview picture into sharper focus. “With DESI, we will be able to independently measure the universe’s expansion rate and how fast its structure of matter and dark matter grow, both of which are influenced by dark energy. Then when you compare those measurements, you get a precise test of the physics governing the universe,” said Risa Wechsler, the current Director of KIPAC and former spokesperson of the DESI collaboration, in comments to The Kavli Foundation in 2017.

    The other part of DESI’s name, “spectroscopic,” refers to how DESI will get the all-important distance measurements to millions of galaxies. DESI contains 5,000 robotic “eyes,” made of human-hair-thin, cosmic-light-gathering fiber optic cables, held in particular orientations by robotic positioners. Each “eye” is pointed at a bright galaxy to collect enough of its stars’ collective light to perform spectroscopy—breaking apart the light into different wavelengths for study. “Whatever light comes down the fiber, we spread out the whole rainbow,” says Roodman. The signature astronomers look for in this light is called redshift, caused by the universe’s expansion, and which can be used to determine a galaxy’s distance.

    With precise distance measurements to an unprecedentedly large swath of galaxies, the DESI researchers will plot the course of dark energy’s influence as never before, better constraining its properties. Roodman, for one, can’t wait.

    “What is causing the expansion of the universe to accelerate is a question I’m very interested in,” says Roodman. “DESI will really teach us something about dark energy.”

    __________________________________________________
    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.
    __________________________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    __________________________________________________

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

     
  • richardmitnick 11:53 am on February 23, 2020 Permalink | Reply
    Tags: , , , , Dark Energy, , , , , , ,   

    From EarthSky: “What is dark matter?” 

    1

    From EarthSky

    February 23, 2020
    Andy Briggs

    Dark Matter doesn’t emit light. It can’t be directly observed with any of the existing tools of astronomers. Yet astrophysicists believe it and Dark Energy make up most of the mass of the cosmos. What dark matter is, and what it isn’t. here.

    1
    Since the 1930s, astrophysicists have been trying to explain why the visible material in galaxies can’t account for how galaxies are shaped, or how they behave. They believe a form of dark or invisible matter pervades our universe, but they still don’t know what this dark matter might be. Image via ScienceAlert.

    Dark matter is a mysterious substance thought to compose perhaps about 27% of the makeup of the universe. What is it? It’s a bit easier to say what it isn’t.

    It isn’t ordinary atoms – the building blocks of our own bodies and all we see around us – because atoms make up only somewhere around 5% of the universe, according to a cosmological model called the Lambda Cold Dark Matter Model (aka the Lambda-CDM model, or sometimes just the Standard Model).

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes
    Alex Mittelmann, Coldcreation

    Dark Matter isn’t the same thing as Dark Energy, which makes up some 68% of the universe, according to the Standard Model.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    Dark matter is invisible; it doesn’t emit, reflect or absorb light or any type of electromagnetic radiation such as X-rays or radio waves. Thus, dark matter is undetectable directly, as all of our observations of the universe, apart from the detection of gravitational waves, involve capturing electromagnetic radiation in our telescopes.

    Gravitational waves Werner Benger-ZIB-AEI-CCT-LSU

    Yet dark matter does interact with ordinary matter. It exhibits measurable gravitational effects on large structures in the universe such as galaxies and galaxy clusters. Because of this, astronomers are able to make maps of the distribution of dark matter in the universe, even though they cannot see it directly.

    They do this by measuring the effect dark matter has on ordinary matter, through gravity.

    2
    This all-sky image – released in 2013 – shows the distribution of dark matter across the entire history of the universe as seen projected on the sky. It’s based on data collected with the European Space Agency’s Planck satellite.

    ESA/Planck 2009 to 2013

    Dark blue areas represent regions that are denser than their surroundings. Bright areas represent less dense regions. The gray portions of the image correspond to patches of the sky where foreground emission, mainly from the Milky Way but also from nearby galaxies, prevents cosmologists from seeing clearly. Image via ESA.

    There is currently a huge international effort to identify the nature of dark matter. Bringing an armory of advanced technology to bear on the problem, astronomers have designed ever-more complex and sensitive detectors to tease out the identity of this mysterious substance.

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA


    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    Dark matter might consist of an as yet unidentified subatomic particle of a type completely different from what scientists call baryonic matter – that’s just ordinary matter, the stuff we see all around us – which is made of ordinary atoms built of protons and neutrons.

    The list of candidate subatomic particles breaks down into a few groups: there are the WIMPs (Weakly Interacting Massive Particles), a class of particles thought to have been produced in the early universe. Astronomers believe that WIMPs might self-annihilate when colliding with each other, so they have searched the skies for telltale traces of events such as the release of neutrinos or gamma rays. So far, they’ve found nothing. In addition, although a theory called supersymmetry predicts the existence of particles with the same properties as WIMPs, repeated searches to find the particles directly have also found nothing, and experiments at the Large Hadron Collider to detect the expected presence of supersymmetry have completely failed to find it.

    Standard Model of Supersymmetry via DESY

    CERN/LHC Map


    CERN LHC Maximilien Brice and Julien Marius Ordan


    SixTRack CERN LHC particles

    Several different types of detector have been used to detect WIMPs. The general idea is that very occasionally, a WIMP might collide with an ordinary atom and release a faint flash of light, which can be detected. The most sensitive detector built to date is XENON1T, which consists of a 10-meter cylinder containing 3.2 tons of liquid xenon, surrounded by photomultipliers to detect and amplify the incredibly faint flashes from these rare interactions. As of July 2019, when the detector was decommissioned to pave the way for a more sensitive instrument, the XENONnT, no collisions between WIMPs and the xenon atoms had been seen.

    XENON1T at Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy


    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

    At the moment, a hypothetical particle called the Axion is receiving much attention.

    CERN CAST Axion Solar Telescope

    As well as being a strong candidate for dark matter, the existence of axions is also thought to provide the answers to a few other persistent questions in physics such as the Strong CP Problem.

    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    Some astronomers have tried to negate the need the existence of dark matter altogether by postulating something called Modified Newtonian dynamics (MOND).

    Mordehai Milgrom, MOND theorist, is an Israeli physicist and professor in the department of Condensed Matter Physics at the Weizmann Institute in Rehovot, Israel http://cosmos.nautil.us

    MOND Modified Newtonian Dynamics a Humble Introduction Marcus Nielbock

    The idea behind this is that gravity behaves differently over long distances to what it does locally, and this difference of behavior explains phenomena such as galaxy rotation curves which we attribute to dark matter. Although MOND has its supporters, while it can account for the rotation curve of an individual galaxy, current versions of MOND simply cannot account for the behavior and movement of matter in large structures such as galaxy clusters and, in its current form, is thought unable to completely account for the existence of dark matter. That is to say, gravity does behave in the same way at all scales of distance. Most versions of MOND, on the other hand, have two versions of gravity, the weaker one occurring in regions of low mass concentration such as in the outskirts of galaxies. However, it is not inconceivable that some new version of MOND in the future might yet account for dark matter.

    Although some astronomers believe we will establish the nature of dark matter in the near future, the search so far has proved fruitless, and we know that the universe often springs surprises on us so that nothing can be taken for granted.

    The approach astronomers are taking is to eliminate those particles which cannot be dark matter, in the hope we will be left with the one which is.

    It remains to be seen if this approach is the correct one.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 6:05 pm on February 20, 2020 Permalink | Reply
    Tags: "Stargazing with Computers: What Machine Learning Can Teach Us about the Cosmos", , , , , , Dark Energy, , , Vera C Rubin Observatory   

    From Argonne National Laboratory: “Stargazing with Computers: What Machine Learning Can Teach Us about the Cosmos” 

    Argonne Lab
    News from From Argonne National Laboratory

    February 18, 2020
    Shannon Brescher Shea
    shannon.shea@science.doe.gov

    Gazing up at the night sky in a rural area, you’ll probably see the shining moon surrounded by stars. If you’re lucky, you might spot the furthest thing visible with the naked eye – the Andromeda galaxy.

    Andromeda Galaxy Adam Evans

    It’s the nearest neighbor to our galaxy, the Milky Way. But that’s just the tiniest fraction of what’s out there. When the Department of Energy’s (DOE) Legacy Survey of Space and Time (LSST) Camera at the National Science Foundation’s Vera Rubin Observatory turns on in 2022, it will take photos of 37 billion galaxies and stars over the course of a decade.

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    The Vera C. Rubin Observatory Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background [CMB]hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    [caption id="attachment_73741" align="alignnone" width="632"] CMB per ESA/Planck

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA


    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    The output from this huge telescope will swamp researchers with data. In those 10 years, the Vera C Rubin Observatory Camera will take 2,000 photos for each patch of the Southern Sky it covers. Each image can have up to a million objects in it.

    “In terms of the scale of the data, the amount of the data, the complexity of the data, they’re well beyond any of the current data sets we have,” said Rachel Mandelbaum, a professor at Carnegie Mellon University and LSST Dark Energy Science Collaboration spokesperson. “This opens up a huge amount of discovery space.”

    Scientists aren’t building the LSST Camera to just take pretty pictures. They want to identify, categorize, and measure celestial objects that can reveal information about the very structure of the universe. Understanding dark energy and other cosmological mysteries requires data on supernovae and galaxies. Researchers may even find entirely new classes of objects.

    “There are going to be some objects that we have never seen before because that is the point of new discovery,” said Renée Hložek, an assistant professor of astrophysics at the University of Toronto, who works with the LSST Dark Energy Science Collaboration. “We will find a bunch of what we call weirdos, or anomalies.”

    The sheer volume and strangeness of the data will make it difficult to analyze. While a stargazer new to an area might go out in the field with a local expert, scientists don’t have such a guide to new pieces of the universe. So they’re making their own. More accurately, they’re making many different guides that can help them identify and categorize these objects. Astrophysicists supported by the DOE Office of Science are developing these guides in the form of computer models that rely on machine learning to examine the Vera C Rubin Observatory data. Machine learning is a process where a computer program learns over time about the relationships in a set of data.

    Computer Programs that Learn

    Processing data quickly is a must for scientists in the Dark Energy Science Collaboration.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    “There are going to be some objects that we have never seen before because that is the point of new discovery,” said Renée Hložek, an assistant professor of astrophysics at the University of Toronto, who works with the LSST Dark Energy Science Collaboration. “We will find a bunch of what we call weirdos, or anomalies.”

    The sheer volume and strangeness of the data will make it difficult to analyze. While a stargazer new to an area might go out in the field with a local expert, scientists don’t have such a guide to new pieces of the universe. So they’re making their own. More accurately, they’re making many different guides that can help them identify and categorize these objects. Astrophysicists supported by the DOE Office of Science are developing these guides in the form of computer models that rely on machine learning to examine the LSST data. Machine learning is a process where a computer program learns over time about the relationships in a set of data.

    Computer Programs that Learn

    Processing data quickly is a must for scientists in the Dark Energy Science Collaboration. Scientists need to know that the camera is pointing at exactly the right place and taking data correctly each time. This quick processing also helps them know if anything has changed in that part of the sky since the last time they took photos of it. Subtracting the current photo from previous ones shows them if there’s a sign of an interesting celestial object or phenomenon.

    They also need to combine a lot of photos together in a way that’s accurate and usable. This project is looking into the depths of the universe to capture images of some of the faintest stars and galaxies. It will also be taking photos in less-than-ideal atmospheric conditions. To compensate, scientists need programs that can combine images together to improve clarity.

    Machine learning can tackle these challenges in addition to handling the sheer amount of data. As these programs analyze more data, the more accurate they become. Just like a person learning to identify a constellation, they gain better judgement over time.

    “Many scientists regard machine learning as the most promising option for classifying sources based on photometric measurements (measurements of light intensity),” said Eve Kovacs, a physicist at DOE’s Argonne National Laboratory.

    But machine learning programs need to teach themselves before they can tackle a pile of new data. There are two main ways to “train” a machine learning program: unsupervised and supervised.

    Unsupervised machine learning is like someone teaching themselves about stars from just their nightly observations. The program trains itself on unlabeled data. While unsupervised machine learning can group images and identify outliers, it can’t categorize them without a guidebook of some sort.

    Supervised machine learning is like a newbie relying on a guidebook. The researchers feed it a massive set of data that is labeled with the classes of each object. By examining the data over and over, the program learns the relationship between the observation and the labels. This technique is especially useful for classifying objects into known groups.

    In some cases, the researchers also feed the program a specific set of features to look for, like brightness, shape, or color. They provide guidance on how important each feature is compared to the others. In other programs, the machine learning program figures out the relevant features itself.

    However, the accuracy of supervised machine learning depends on having a good training set, with all of the diversity and variability of a real one. For photos from the LSST Camera, that variability could include streaks from satellites moving across the sky. The labeling also has to be extremely accurate.

    “We have to put as much physics as we can into the training sets,” said Mandelbaum. “It doesn’t remove from us the burden to understand the physics. It just moves it into a different part of the problem.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

     
  • richardmitnick 3:54 pm on January 29, 2020 Permalink | Reply
    Tags: CBR, Dark Energy, , , , How standard are "standard candles"?, , , Solid experimental evidence but unsatisfying theories,   

    From FNAL via Inside Science: “Dark Energy Skeptics Raise Concerns, But Remain Outnumbered” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    via

    Inside Science

    January 24, 2020
    Ramin Skibba

    Some scientists have been poking at the foundations of dark energy, but many say the concept remains on solid, if mysterious, ground.

    2
    Spiral galaxy NGC 5714. In 2003, a faint supernova (not visible in this later picture) appeared about 8000 light-years below the central bulge of NGC 5714. European Space Agency via Flickr. CC BY 2.0

    Since the dawn of the universe, the biggest stars have ended their lives with a bang, blowing out their outer layers in bright, fiery bursts that can be seen many light-years away. Astronomers use these supernova explosions like marks on an expanding balloon to measure how fast the universe is growing.

    Based on studies of dozens of supernova explosions, astronomers in the late 1990s realized that the universe’s expansion seems to be accelerating. They hypothesized that some unseen “energy,” which works the opposite of gravity, was pushing everything outward. The concept of so-called dark energy quickly became popular, and ultimately, scientists’ consensus view. It earned three physicists the 2011 Nobel Prize.

    Saul Perlmutter [The Supernova Cosmology Project] shared the 2006 Shaw Prize in Astronomy, the 2011 Nobel Prize in Physics, and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt and Adam Riess [The High-z Supernova Search Team] for providing evidence that the expansion of the universe is accelerating.

    Recently, however, some scientists have been poking at this foundation of dark energy research.

    A team of Korean scientists published findings on Jan. 5 questioning the reliability of using supernovae to measure intergalactic distances. This followed a paper published in November [Astronomy and Astrophysics] that also cast doubt on the supernova evidence from a different angle, arguing that our galactic neighborhood is flowing in a particular direction, affecting certain kinds of distance measurements.

    In both instances, other scientists pushed back, noting potential flaws in the methodology and conclusions of the new studies.

    While most scientists still seem to believe that dark energy remains on solid ground, no one yet has any firm idea what it actually is.

    How standard are “standard candles”?

    Standard Candles to measure age and distance of the universe from supernovae. NASA

    Every time a star goes supernova, its radiant explosion follows such a familiar pattern that scientists nicknamed them “standard candles.” Assuming supernovae are predictable that way, astronomers can estimate how far away they are mainly based on how bright they appear. They can then map the universe’s expansion history by studying supernova both nearby and far away — that is, both recent and from a long time ago.

    It’s like gauging how far away vehicles are at night by looking at their headlights. If you made incorrect assumptions about what kinds of vehicles they are — for example assuming they are trucks with bright lights a long distance away when they are in fact smaller vehicles much closer — then your data and your inferences about the length of the road would be skewed.

    Young-Wook Lee, an astronomer at Yonsei University in South Korea and lead author of the Jan. 5 study, and his colleagues question a common and important assumption in the standard candle approach: that the brightness or luminosity of supernova explosions don’t vary when you look further back into the universe’s past.

    To test their hypothesis, they studied supernova in galaxies whose stars’ ages had been precisely measured and found that the brightness of a supernova depends on the ages of its host galaxy’s stellar population. The stars that produce supernovae are generally younger, further in the universe’s past, which is problematic for physicists estimating the universe’s expansion rate.

    “Supernova luminosity should vary as a function of cosmic time, and that hasn’t been accounted for in the so-called ‘discovery’ of dark energy,” said Lee.

    But to Dragan Huterer, an astrophysicist at the University of Michigan in Ann Arbor, the data from the paper doesn’t warrant a sweeping reconsideration of dark energy.

    “These evolution effects have not been observed to be strong, and cosmologists partly take them into account,” Huterer argued. He conceded there may be a small correlation, but not one large enough to shake the foundation of dark energy’s consensus. “I’d bet my life on it,” he said.

    Joshua Frieman, a Fermilab astrophysicist, thinks Lee and his team are doing legitimate research, but is also skeptical about whether one could draw sweeping conclusions from it. He points out that the study’s findings show only a weak trend with age; they use a model that estimates ages of a few supernova older than the universe’s age; and they focus only on a small sample of elliptical galaxies, while the scope of supernova studies that support dark energy include all kinds of galaxies.

    Solid experimental evidence, but unsatisfying theories

    While many scientists argue against overinterpreting results that seem to question the foundations of dark energy, both of the recent papers fall into accepted lines of research. Supernova cosmology has for years been plagued by questions about systematic uncertainties infecting every step of calculations, including how their fluxes and light curves are measured and calibrated. Researchers need to account for every factor, no matter how small, that could muddy a study of the expanding universe. And there’s always a concern for something missed, an unknown unknown.

    Such concerns are actually evidence of a well-developed field, argued Tamara Davis, an astrophysicist at the University of Queensland in Australia. “Once a field becomes very mature, the tiny details that were negligible before become more important,” said Davis. A focus on myriad uncertainties that affect a measurement by just a percent or two is actually a sign that the measurement’s quite good already, she argued.

    Astronomers’ current controversy over the precise value of the Hubble constant, which describes how fast the universe is expanding, reflects a similarly mature field, she said. (This question about the exact expansion rate is different than the one about whether the rate’s accelerating.) That research, similar to supernova cosmology, has made great strides since the 1990s, and now small, previously ignored discrepancies come to the fore.

    Most scientists Inside Science interviewed feel dark energy is still on solid ground. Even if Lee’s study and others like it discredited the kinds of supernova cosmology findings that formed the groundwork for dark energy research, other kinds of research now also point toward dark energy, Frieman argued. This includes studies of fluctuations in the cosmic microwave background [CMB] radiation — radiation [CBR] that’s thought to be left over from soon after the Big Bang and which bears an imprint of the growing universe when it was young — and studies of the large-scale structure of the universe, involving surveys of hundreds of thousands of galaxies over a wide area.

    CMB per ESA/Planck

    CBR per ESA/Planck

    “Yes, in 1998, you could’ve said, ‘There are supernova systematic uncertainties, so maybe the universe isn’t accelerating,'” Frieman said. “But in 2020, we now have multiple pieces of evidence that the stool holding up dark energy is much more stable, so you could knock out supernova and still say we have strong evidence for cosmic acceleration from these other probes.”

    Current and upcoming experiments could add yet more precision to studies of dark energy. These include the Dark Energy Survey, the Dark Energy Spectroscopic Instrument, space-based missions, and the newly renamed Vera Rubin Observatory, being built in northern Chile. But theoretical physicists are behind, Huterer said, as they still don’t have a compelling explanation for what dark energy is and where it came from.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018

    NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The LSST, or Large Synoptic Survey Telescope renamed named the Vera C. Rubin Observatory by an act of the U.S. Congress.

    LSST telescope, The Vera Rubin Survey Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    “I think the precision on dark energy parameters is definitely going to be improving with these missions,” Frieman said. The data so far is consistent with the idea of dark energy as a simple cosmological constant, a ubiquitous vacuum energy somehow produced by the universe’s expansion that generates yet more expansion. But Frieman hopes new data may reveal something more exotic, such as a mysterious substance called quintessence, which some scientists have proposed could explain the accelerating expansion of the universe. Which theory will be ahead 10 years from now “is anyone’s guess,” Freiman said.

    See the full here.


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 7:26 am on January 17, 2020 Permalink | Reply
    Tags: , , , , Dark Energy, , ,   

    From European Space Agency – United space in Europe: “XMM-Newton discovers scorching gas in Milky Way’s halo” 

    ESA Space For Europe Banner

    From European Space Agency – United space in Europe

    From United space in Europe

    16/01/2020

    Sanskriti Das
    The Ohio State University, USA
    das.244@buckeyemail.osu.edu

    Smita Mathur
    The Ohio State University, USA
    smita@astronomy.ohio-state.edu

    Fabrizio Nicastro
    Osservatorio Astronomico di Roma—INAF, Italy
    Harvard-Smithsonian Center for Astrophysics, USA
    fabrizio.nicastro@inaf.it

    Norbert Schartel
    XMM-Newton project scientist
    European Space Agency
    norbert.schartel@esa.int

    1

    ESA’s XMM-Newton has discovered that gas lurking within the Milky Way’s halo reaches far hotter temperatures than previously thought and has a different chemical make-up than predicted, challenging our understanding of our galactic home.

    ESA/XMM Newton

    A halo is a vast region of gas, stars and invisible dark matter surrounding a galaxy. It is a key component of a galaxy, connecting it to wider intergalactic space, and is thus thought to play an important role in galactic evolution.

    Until now, a galaxy’s halo was thought to contain hot gas at a single temperature, with the exact temperature of this gas dependent on the mass of the galaxy.

    However, a new study using ESA’s XMM-Newton X-ray space observatory now shows that the Milky Way’s halo contains not one but three different components of hot gas, with the hottest of these being a factor of ten hotter than previously thought. This is the first time multiple gas components structured in this way have been discovered in not only the Milky Way, but in any galaxy.

    “We thought that gas temperatures in galactic haloes ranged from around 10,000 to one million degrees – but it turns out that some of the gas in the Milky Way’s halo can hit a scorching 10 million degrees,” says Sanskriti Das, a graduate student at The Ohio State University, USA, and lead author of the new study.

    “While we think that gas gets heated to around one million degrees as a galaxy initially forms, we’re not sure how this component got so hot. It may be due to winds emanating from the disc of stars within the Milky Way.”

    The study used a combination of two instruments aboard XMM-Newton: the Reflection Grating Spectrometer (RGS) and European Photon Imaging Camera (EPIC). EPIC was used to study the light emitted by the halo, and RGS to study how the halo affects and absorbs light that passes through it.

    To probe the Milky Way’s halo in absorption, Sanskriti and colleagues observed an object known as a blazar: the very active, energetic core of a distant galaxy that is emitting intense beams of light.

    By now iconic image of a blazar. NASA Fermi Gamma ray Space Telescope. Credits M. Weiss/ CfA

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    Having travelled almost five billion light-years across the cosmos, the X-ray light from this blazar also passed through our galaxy’s halo before reaching XMM-Newton’s detectors, and thus holds clues about the properties of this gaseous region.

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

    Unlike previous X-ray studies of the Milky Way’s halo, which normally last a day or two, the team performed observations over a period of three weeks, enabling them to detect signals that are usually too faint to see.

    “We analysed the blazar’s light and zeroed in on its individual spectral signatures: the characteristics of the light that can tell us about the material it’s passed through on its way to us,” says co-author Smita Mathur, also of The Ohio State University, and Sanskriti’s advisor.

    “There are specific signatures that only exist at specific temperatures, so we were able to determine how hot the halo gas must have been to affect the blazar light as it did.”

    The Milky Way’s hot halo is also significantly enhanced with elements heavier than helium, which are usually produced in the later stages of a star’s life. This indicates that the halo has received material created by certain stars during their lifetimes and final stages, and flung out into space as they die.

    3
    Elements found in the Milky Way halo – artist’s impression

    “Until now, scientists have primarily looked for oxygen, as it’s abundant and thus easier to find than other elements,” explains Sanskriti.

    “Our study was more detailed: we looked at not only oxygen but also nitrogen, neon and iron, and found some hugely interesting results.”

    Scientists expect the halo to contain elements in similar ratios to those seen in the Sun. However, Das and colleagues noticed less iron in the halo than expected, indicating that the halo has been enriched by massive dying stars, and also less oxygen, likely due to this element being taken up by dusty particles in the halo.

    “This is really exciting – it was completely unexpected, and tells us that we have much to learn about how the Milky Way has evolved into the galaxy it is today,” adds Sanskriti.

    4
    The cosmic budget of ‘ordinary’ matter

    While the mysterious dark matter and dark energy make up about 25 and 70 percent of our cosmos respectively, the ordinary matter that makes up everything we see – from stars and galaxies to planets and people – amounts to only about five percent.

    ______________________________________________________________________

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The LSST, or Large Synoptic Survey Telescope is to be named the Vera C. Rubin Observatory by an act of the U.S. Congress.

    LSST telescope, The Vera Rubin Survey Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background [CMB]hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    [caption id="attachment_73741" align="alignnone" width="632"] CMB per ESA/Planck

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA


    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    ______________________________________________________________________

    However, stars in galaxies across the Universe only make up about seven percent of all ordinary matter. The cold interstellar gas that permeates galaxies – the raw material to create stars – amounts to about 1.8 percent of total, while the hot, diffuse gas in the haloes that encompass galaxies makes up roughly five percent, and the even hotter gas that fills galaxy clusters – the largest cosmic structures held together by gravity – accounts for four percent.

    This is not surprising: stars, galaxies and galaxy clusters form in the densest knots of the cosmic web, the filamentary distribution of both dark and ordinary matter that extends throughout the Universe. While these sites are dense, they are also rare, so not the best spots to look for the majority of cosmic matter.

    Most of the Universe’s ordinary matter, or baryons, must be lurking in the ubiquitous filaments of this cosmic web, where matter is however less dense and therefore more challenging to observe. Using different techniques over the years, they were able to locate a good chunk of this intergalactic material – mainly its cool component (also known as Lyman-alpha forest, which makes up about 28 percent of all baryons) and its warm component (about 15 percent).

    After two decades of observations, astronomers using ESA’s XMM-Newton space observatory have detected the hot component of this intergalactic material along the line of sight to a distant quasar. The amount of hot intergalactic gas detected in these observations amounts up to 40 percent of all baryons in the Universe, closing the gap in the overall budget of ordinary matter in the cosmos.

    The newly discovered hot gas component also has wider implications that affect our overall understanding of the cosmos. Our galaxy contains far less mass than we expect: this is known as the ‘missing matter problem’, in that what we observe does not match up with theoretical predictions.

    From its long-term mapping of the cosmos, ESA’s Planck spacecraft predicted that just under 5% of the mass in the Universe should exist in the form of ‘normal’ matter – the kind making up stars, galaxies, planets, and so on.

    ESA/Planck 2009 to 2013

    “However, when we add up everything we see, our figure is nowhere by S. Das, S. Mathur, F. Nicastro, and Y. Krongold near this prediction,” adds co-author Fabrizio Nicastro of Osservatorio Astronomico di Roma—INAF, Italy, and the Harvard-Smithsonian Center for Astrophysics, USA.

    “So where’s the rest? Some suggest that it may be hiding in the extended and massive halos surrounding galaxies, making our finding really exciting.”

    As this hot component of the Milky Way’s halo has never been seen before, it may have been overlooked in previous analyses – and may thus contain a large amount of this ‘missing’ matter.

    “These observations provide new insights into the thermal and chemical history of the Milky Way and its halo, and challenge our knowledge of how galaxies form and evolve,” concludes ESA XMM project scientist Norbert Schartel.

    “The study looked at the halo along one sightline – that towards the blazar – so it will be hugely exciting to see future research expand on this.”

    Science papers:
    https://iopscience.iop.org/article/10.3847/2041-8213/ab3b09 , by S. Das, S. Mathur, F. Nicastro, and Y. Krongold

    https://iopscience.iop.org/article/10.3847/1538-4357/ab5846 , S. Das, S. Mathur, A, Gupta, F. Nicastro, and Y. Krongold

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

    ESA50 Logo large

     
  • richardmitnick 2:19 pm on January 14, 2020 Permalink | Reply
    Tags: "Have Dark Forces Been Messing With the Cosmos?", Alan Guth MIT "Inflation", , , , , CMB per Planck, , Dark Energy, , Discrepancy in how fast the niverse is expanding., Edwin Hubble in 1929 discovers the Universe is Expanding, , , Saul Perlmutter [The Supernova Cosmology Project] shared the 2006 Shaw Prize in Astronom; the 2011 Nobel Prize in Physics; and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt ,   

    From The New York Times: “Have Dark Forces Been Messing With the Cosmos?” 


    From The New York Times

    Feb. 25, 2019 [Sorry, missed the first time around. Picked up from another article found today by Dennis Overbye]
    Dennis Overbye

    1
    Brian Stauffer

    There was, you might say, a disturbance in the Force.

    Long, long ago, when the universe was only about 100,000 years old — a buzzing, expanding mass of particles and radiation — a strange new energy field switched on. That energy suffused space with a kind of cosmic antigravity, delivering a not-so-gentle boost to the expansion of the universe.

    Then, after another 100,000 years or so, the new field simply winked off, leaving no trace other than a speeded-up universe.

    So goes the strange-sounding story being promulgated by a handful of astronomers from Johns Hopkins University. In a bold and speculative leap into the past, the team has posited the existence of this field to explain an astronomical puzzle: the universe seems to be expanding faster than it should be.

    The cosmos is expanding only about 9 percent more quickly than theory prescribes. But this slight-sounding discrepancy has intrigued astronomers, who think it might be revealing something new about the universe.

    And so, for the last couple of years, they have been gathering in workshops and conferences to search for a mistake or loophole in their previous measurements and calculations, so far to no avail.

    “If we’re going to be serious about cosmology, this is the kind of thing we have to be able to take seriously,” said Lisa Randall, a Harvard theorist who has been pondering the problem.

    At a recent meeting in Chicago, Josh Frieman, a theorist at the Fermi National Accelerator Laboratory [FNAL] in Batavia, Ill., asked: “At what point do we claim the discovery of new physics?”

    Now ideas are popping up. Some researchers say the problem could be solved by inferring the existence of previously unknown subatomic particles. Others, such as the Johns Hopkins group, are invoking new kinds of energy fields.

    Adding to the confusion, there already is a force field — called dark energy — making the universe expand faster.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    And a new, controversial report suggests that this dark energy might be getting stronger and denser, leading to a future in which atoms are ripped apart and time ends.

    Thus far, there is no evidence for most of these ideas. If any turn out to be right, scientists may have to rewrite the story of the origin, history and, perhaps, fate of the universe.

    Or it could all be a mistake. Astronomers have rigorous methods to estimate the effects of statistical noise and other random errors on their results; not so for the unexamined biases called systematic errors.

    As Wendy L. Freedman, of the University of Chicago, said at the Chicago meeting, “The unknown systematic is what gets you in the end.”

    Edwin Hubble looking through a 100-inch Hooker telescope at Mount Wilson in Southern California, 1929 discovers the Universe is Expanding

    Edwin Hubble in 1949, two decades after he discovered that the universe is expanding.Credit…Boyer/Roger Viollet, via Getty Images (credit: Emilio Segre Visual Archives/AIP/SPL)

    Hubble trouble

    Generations of great astronomers have come to grief trying to measure the universe. At issue is a number called the Hubble constant, named after Edwin Hubble, the Mount Wilson astronomer who in 1929 discovered that the universe is expanding.

    As space expands, it carries galaxies away from each other like the raisins in a rising cake. The farther apart two galaxies are, the faster they will fly away from each other. The Hubble constant simply says by how much.

    But to calibrate the Hubble constant, astronomers depend on so-called standard candles: objects, such as supernova explosions and certain variable stars, whose distances can be estimated by luminosity or some other feature. This is where the arguing begins.

    Standard Candles to measure age and distance of the universe from supernovae. NASA

    Until a few decades ago, astronomers could not agree on the value of the Hubble constant within a factor of two: either 50 or 100 kilometers per second per megaparsec. (A megaparsec is 3.26 million light years.)

    But in 2001, a team using the Hubble Space Telescope, and led by Dr. Freedman, reported a value of 72. For every megaparsec farther away from us that a galaxy is, it is moving 72 kilometers per second faster.

    More recent efforts by Adam G. Riess [The Astrophysical Journal], of Johns Hopkins and the Space Telescope Science Institute, and others have obtained similar numbers, and astronomers now say they have narrowed the uncertainty in the Hubble constant to just 2.4 percent.

    But new precision has brought new trouble. These results are so good that they now disagree with results from the European Planck spacecraft, which predict a Hubble constant of 67.

    The discrepancy — 9 percent — sounds fatal but may not be, astronomers contend, because Planck and human astronomers do very different kinds of observations.

    Planck is considered the gold standard of cosmology. It spent four years studying the cosmic bath of microwaves [CMB] left over from the end of the Big Bang, when the universe was just 380,000 years old.

    CMB per ESA/Planck


    ESA/Planck 2009 to 2013

    But it did not measure the Hubble constant directly. Rather, the Planck group derived the value of the constant, and other cosmic parameters, from a mathematical model largely based on those microwaves.

    In short, Planck’s Hubble constant is based on a cosmic baby picture. In contrast, the classical astronomical value is derived from what cosmologists modestly call “local measurements,” a few billion light-years deep into a middle-aged universe.

    What if that baby picture left out or obscured some important feature of the universe?

    ‘Cosmological Whac-a-Mole’

    And so cosmologists are off to the game that Lloyd Knox, an astrophysicist from the University of California, Davis, called “cosmological Whac-a-Mole” at the recent Chicago meeting: attempting to fix the model of the early universe, to make it expand a little faster without breaking what the model already does well.

    One approach, some astrophysicists suggest, is to add more species of lightweight subatomic particles, such as the ghostlike neutrinos, to the early universe. (Physicists already recognize three kinds of neutrinos, and argue whether there is evidence for a fourth variety.) These would give the universe more room to stash energy, in the same way that more drawers in your dresser allow you to own more pairs of socks. Thus invigorated, the universe would expand faster, according to the Big Bang math, and hopefully not mess up the microwave baby picture.

    A more drastic approach, from the Johns Hopkins group, invokes fields of exotic anti-gravitational energy. The idea exploits an aspect of string theory, the putative but unproven “theory of everything” that posits that the elementary constituents of reality are very tiny, wriggling strings.

    String theory suggests that space could be laced with exotic energy fields associated with lightweight particles or forces yet undiscovered. Those fields, collectively called quintessence, could act in opposition to gravity, and could change over time — popping up, decaying or altering their effect, switching from repulsive to attractive.

    The team focused in particular on the effects of fields associated with hypothetical particles called axions. Had one such field arisen when the universe was about 100,000 years old, it could have produced just the right amount of energy to fix the Hubble discrepancy, the team reported in a paper late last year. They refer to this theoretical force as “early dark energy.”

    “I was surprised how it came out,” said Marc Kamionkowski, a Johns Hopkins cosmologist who was part of the study. “This works.”

    The jury is still out. Dr. Riess said that the idea seems to work, which is not to say that he agrees with it, or that it is right. Nature, manifest in future observations, will have the final say.

    Dr. Knox called the Johns Hopkins paper “an existence proof” that the Hubble problem could be solved. “I think that’s new,” he said.

    Dr. Randall, however, has taken issue with aspects of the Johns Hopkins calculations. She and a trio of Harvard postdocs are working on a similar idea that she says works as well and is mathematically consistent. “It’s novel and very cool,” Dr. Randall said.

    So far, the smart money is still on cosmic confusion. Michael Turner, a veteran cosmologist at the University of Chicago and the organizer of a recent airing of the Hubble tensions, said, “Indeed, all of this is going over all of our heads. We are confused and hoping that the confusion will lead to something good!”

    Doomsday? Nah, nevermind

    Early dark energy appeals to some cosmologists because it hints at a link to, or between, two mysterious episodes in the history of the universe. As Dr. Riess said, “This is not the first time the universe has been expanding too fast.”

    The first episode occurred when the universe was less than a trillionth of a trillionth of a second old. At that moment, cosmologists surmise, a violent ballooning propelled the Big Bang; in a fraction of a trillionth of a second, this event — named “inflation” by the cosmologist Alan Guth, of M.I.T. — smoothed and flattened the initial chaos into the more orderly universe observed today.

    Inflation

    4
    Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes
    Alex Mittelmann, Coldcreation

    Alan Guth’s notes:

    Alan Guth’s original notes on inflation

    Nobody knows what drove inflation.

    The second episode is unfolding today: cosmic expansion is speeding up. But why? The issue came to light in 1998, when two competing teams of astronomers asked whether the collective gravity of the galaxies might be slowing the expansion enough to one day drag everything together into a Big Crunch.

    To great surprise, they discovered the opposite: the expansion was accelerating under the influence of an anti-gravitational force later called dark energy. The two teams won a Nobel Prize.

    Saul Perlmutter [The Supernova Cosmology Project] shared the 2006 Shaw Prize in Astronomy, the 2011 Nobel Prize in Physics, and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt and Adam Riess [The High-z Supernova Search Team] for providing evidence that the expansion of the universe is accelerating.

    Dark energy comprises 70 percent of the mass-energy of the universe. And, spookily, it behaves very much like a fudge factor known as the cosmological constant, a cosmic repulsive force that Einstein inserted in his equations a century ago thinking it would keep the universe from collapsing under its own weight. He later abandoned the idea, perhaps too soon.

    Under the influence of dark energy, the cosmos is now doubling in size every 10 billion years — to what end, nobody knows.

    Early dark energy, the force invoked by the Johns Hopkins group, might represent a third episode of antigravity taking over the universe and speeding it up. Perhaps all three episodes are different manifestations of the same underlying tendency of the universe to go rogue and speed up occasionally. In an email, Dr. Riess said, “Maybe the universe does this from time-to-time?”

    If so, it would mean that the current manifestation of dark energy is not Einstein’s constant after all. It might wink off one day. That would relieve astronomers, and everybody else, of an existential nightmare regarding the future of the universe. If dark energy remains constant, everything outside our galaxy eventually will be moving away from us faster than the speed of light, and will no longer be visible. The universe will become lifeless and utterly dark.

    But if dark energy is temporary — if one day it switches off — cosmologists and metaphysicians can all go back to contemplating a sensible tomorrow.

    “An appealing feature of this is that there might be a future for humanity,” said Scott Dodelson, a theorist at Carnegie Mellon who has explored similar scenarios.

    The phantom cosmos

    But the future is still up for grabs.

    Far from switching off, the dark energy currently in the universe actually has increased over cosmic time, according to a recent report in Nature Astronomy. If this keeps up, the universe could end one day in what astronomers call the Big Rip, with atoms and elementary particles torn asunder — perhaps the ultimate cosmic catastrophe.

    This dire scenario emerges from the work of Guido Risaliti, of the University of Florence in Italy, and Elisabeta Lusso, of Durham University in England. For the last four years, they have plumbed the deep history of the universe, using violent, faraway cataclysms called quasars as distance markers.

    Quasars arise from supermassive black holes at the centers of galaxies; they are the brightest objects in nature, and can be seen clear across the universe. As standard candles, quasars aren’t ideal because their masses vary widely. Nevertheless, the researchers identified some regularities in the emissions from quasars, allowing the history of the cosmos to be traced back nearly 12 billion years. The team found that the rate of cosmic expansion deviated from expectations over that time span.

    One interpretation of the results is that dark energy is not constant after all, but is changing, growing denser and thus stronger over cosmic time. It so happens that this increase in dark energy also would be just enough to resolve the discrepancy in measurements of the Hubble constant.

    The bad news is that, if this model is right, dark energy may be in a particularly virulent and — most physicists say — implausible form called phantom energy. Its existence would imply that things can lose energy by speeding up, for instance. Robert Caldwell, a Dartmouth physicist, has referred to it as “bad news stuff.”

    As the universe expands, the push from phantom energy would grow without bounds, eventually overcoming gravity and tearing apart first Earth, then atoms.

    The Hubble-constant community responded to the new report with caution. “If it holds up, this is a very interesting result,” said Dr. Freedman.

    Astronomers have been trying to take the measure of this dark energy for two decades. Two space missions — the European Space Agency’s Euclid and NASA’s Wfirst — have been designed to study dark energy and hopefully deliver definitive answers in the coming decade. The fate of the universe is at stake.

    ESA/Euclid spacecraft depiction

    NASA/WFIRST

    In the meantime, everything, including phantom energy, is up for consideration, according to Dr. Riess.

    “In a list of possible solutions to the tension via new physics, mentioning weird dark energy like this would seem appropriate,” he wrote in an email. “Heck, at least their dark energy goes in the right direction to solve the tension. It could have gone the other way and made it worse!”

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 9:17 pm on January 13, 2020 Permalink | Reply
    Tags: "Connecting the dots in the sky could shed new light on dark matter", , , , , , Dark Energy,   

    From SLAC National Accelerator Lab: “Connecting the dots in the sky could shed new light on dark matter” 

    From SLAC National Accelerator Lab

    January 13, 2020
    Manuel Gnida

    Matching up maps of matter and light from the Dark Energy Survey and Fermi Gamma-ray Space Telescope may help astrophysicists understand what causes a faint cosmic gamma-ray glow.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    NASA/Fermi LAT

    NASA/Fermi Gamma Ray Space Telescope

    Astrophysicists have come a step closer to understanding the origin of a faint glow of gamma rays covering the night sky. They found that this light is brighter in regions that contain a lot of matter and dimmer where matter is sparser – a correlation that could help them narrow down the properties of exotic astrophysical objects and invisible dark matter.

    The glow, known as unresolved gamma-ray background, stems from sources that are so faint and far away that researchers can’t identify them individually. Yet, the fact that the locations where these gamma rays originate match up with where mass is found in the distant universe could be a key puzzle piece in identifying those sources.

    2
    In a new study, astrophysicists have found a certain gamma-ray glow in the sky, known as unresolved gamma-ray background (yellow), to coincide with cosmic regions that contain a lot of matter (red). The correlation could lead to a better understanding of highly energetic astrophysical objects and dark matter. The gamma-ray map was created with nine years of data from the Fermi spacecraft, and the map showing the density of matter is based on one year of data from the Dark Energy Survey (DES). (Daniel Gruen/SLAC/Stanford, Chihway Chang/University of Chicago, Alex Drlica-Wagner/Fermilab)

    The background is the sum of a lot of things ‘out there’ that produce gamma rays. Having been able to measure for the first time its correlation with gravitational lensing – tiny distortions of images of far galaxies produced by the distribution of matter – helps us disentangle them,” said Simone Ammazzalorso from the University of Turin and the National Institute for Nuclear Physics (INFN) in Italy, who co-led the analysis.

    The study used one year of data from the Dark Energy Survey (DES), which takes optical images of the sky, and nine years of data from the Fermi Gamma-ray Space Telescope, which observes cosmic gamma rays while it orbits the Earth.

    “What’s really intriguing is that the correlation we measured doesn’t completely match our expectations,” said Panofsky fellow Daniel Gruen from the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University, who led the analysis for the DES collaboration. “This could mean that we either need to adjust our existing models for objects that emit gamma rays, or it could hint at other sources, such as dark matter.”

    The study was accepted today for publication in Physical Review Letters.

    Two sensitive ‘eyes’ on the sky

    Gamma radiation, the most energetic form of light, is produced in a wide range of cosmic phenomena – often extremely violent ones, such as exploding stars, dense neutron stars rotating at high speeds and powerful beams of particles shooting out of active galaxies whose central supermassive black holes gobble up matter.

    Another potential source is invisible dark matter, which is believed to make up 85 percent of all matter in the universe. It could produce gamma rays when dark matter particles meet and destroy each other in space.

    The Large Area Telescope (LAT) on board the Fermi spacecraft is a highly sensitive “eye” for gamma radiation, and its data provide a detailed map of gamma-ray sources in the sky.

    But when scientists subtract all the sources they already know, their map is far from empty; it still contains a gamma-ray background whose brightness varies from region to region.

    “Unfortunately gamma rays don’t have a label that would tell us where they came from,” Gruen said. “That’s why we need additional information to unravel their origin.”

    That’s where DES comes in. With its 570-megapixel Dark Energy Camera, mounted on the Victor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory in Chile, it snaps images of hundreds of millions of galaxies.

    Cerro Tololo Inter-American Observatory on Cerro Tololo in the Coquimbo Region of northern Chile Altitude 2,207 m (7,241 ft)

    Their exact shapes tell researchers how the gravitational pull of matter bends light in the universe – an effect that shows itself as tiny distortions in galaxy images, known as weak gravitational lensing. Based on these data, the DES researchers create the most detailed maps yet of matter in the cosmos.

    In the new study, the scientists superimposed the Fermi and DES maps, which revealed that the two aren’t independent. The unresolved gamma-ray background is more intense in regions with more matter and less intense in regions with less matter.

    “The result itself is not surprising. We expect that there are more gamma ray producing processes in regions that contain more matter, and we’ve been predicting this correlation for a while,” said Nicolao Fornengo, one of Ammazzalorso’s supervisors in Turin. “But now we’ve succeeded in actually detecting this correlation for the first time, and we can use it to understand what causes the gamma ray background.”

    Potential hint at dark matter.

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The LSST, or Large Synoptic Survey Telescope is to be named the Vera C. Rubin Observatory by an act of the U.S. Congress.

    LSST telescope, The Vera Rubin Survey Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background [CMB]hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    [caption id="attachment_73741" align="alignnone" width="632"] CMB per ESA/Planck

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA


    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    One of the most likely sources for the gamma-ray glow is very distant blazars – active galaxies with supermassive black holes at their centers. As the black holes swallow surrounding matter, they spew high-speed jets of plasma and gamma rays that, if the jets point at us, are detected by the Fermi spacecraft.

    Blazars would be the simplest assumption, but the new data suggest that a simple population of blazars might not be enough to explain the observed correlation between gamma rays and mass distribution, the researchers said.

    5
    By now iconic illustration of a blazar, a powerful object that produces beams of gamma rays when material spirals into a massive black hole. Blazars are the most common extraterrestrial sources of high-energy gamma rays detected by the Fermi Gamma-ray Space Telescope. (M. Weiss/CfA)

    In fact, our models for emissions from blazars can fairly well explain the low-energy part of the correlation, but we see deviations for high-energy gamma rays,” Gruen said. “This can mean several things: It could indicate that we need to improve our models for blazars or that the gamma rays could come from other sources.”

    One of these other sources could be dark matter. A leading theory predicts the mysterious stuff is made of weakly interacting massive particles, or WIMPs, which could annihilate each other in a flash of gamma rays when they collide. Gamma rays from certain matter-rich cosmic regions could therefore stem from these particle interactions.

    The idea to look for gamma-ray signatures of annihilating WIMPs is not a new one. Over the past years, scientists have searched for them in various locations believed to contain a lot of dark matter, including the center of the Milky Way and the Milky Way’s companion galaxies. However, these searches haven’t produced identifiable dark matter signals yet. The new results could be used for additional searches that test the WIMP hypothesis.

    Planning next steps

    Although the probability that the measured correlation is just a random effect is only about one in a thousand, the researchers need more data for a conclusive analysis.

    “These results, connecting for the first time our maps of gamma rays and matter, are very interesting and have a lot of potential, but at the moment the connection is still relatively weak, and one has to interpret the data carefully,” said KIPAC Director Risa Wechsler, who was not involved in the study.

    One of the main limitations of the current analysis is the amount of available lensing data, Gruen said. “With data from 40 million galaxies, DES has already pushed this to a new level, and that’s why we were able to do the analysis in the first place. But we need even better measurements,” he said.

    With its next data release, DES will provide lensing data for 100 million galaxies, and the future Legacy Survey of Space and Time (LSST) at the Vera Rubin Observatory will look at billions of galaxies in a much larger region of the sky.

    “Our study demonstrates with actual data that we can use the correlation between the distributions of matter and gamma rays to learn more about what causes the gamma-ray background,” Fornengo said. “With more DES data, LSST coming online and other projects like the Euclid space telescope on the horizon, we’ll be able to go much deeper in our understanding of the potential sources.”

    ESA/Euclid spacecraft depiction

    Then, the scientists might be able to tell if some of that gamma-ray glow stems from dark matter’s self-destruction.

    DES is an international project with over 400 scientists from 25 institutions in 7 countries, who have come together to carry out the survey. Parts of the project were funded by DOE’s Office of Science and the National Science Foundation. NASA’s Fermi Gamma-ray Space Telescope is an international and multi-agency space observatory. The analysis used Fermi-LAT data that were publicly released by the international LAT collaboration.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 8:36 pm on January 13, 2020 Permalink | Reply
    Tags: , , , Calculate the masses of enormous galaxy clusters using a new mathematical estimator., , , Dark Energy, , Destination: Antarctica-the South Pole Telescope., Destination: Chile-Cerro Tololo Inter-American Observatory-The Dark Energy Camera of the Dark Energy Survey, Destination: Unspoiled places-, , Most of the mass of galaxy clusters isn’t even visible – it’s dark matter.   

    From Fermi National Accelerator Lab: “Data from antipodal places: First use of CMB polarization to detect gravitational lensing from galaxy clusters” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    January 13, 2020
    Catherine N. Steffel

    Galaxies. Amalgamations of stars, interstellar gas, dust, stellar debris and dark matter. They waltz through the cold universe, gravity nurturing their embrace. Occasionally, galaxies snowball into enormous galaxy clusters with masses averaging 100 trillion times that of our sun.

    But this wasn’t always the case.

    In the infant universe, temperatures were so high that electrons and protons were too hot to form atoms. Everything was a hot, ionized gas, not unlike the surface of the sun.

    Over the next 400,000 years, the universe expanded and cooled to around 3,000 degrees Celsius, about the temperature of an industrial furnace. At these temperatures, electrons and protons combined into hydrogen atoms and released photons in the process. This light, called the cosmic microwave background radiation, has been traveling through space ever since, a watermark of space and time.

    Now, scientists have found new ways to tease information out of this inexhaustible time machine.

    Constraining cosmology with CMB polarization

    In a study published in Physical Review Letters, Fermilab and University of Chicago scientist Brad Benson and colleagues use the polarization, or orientation, of the cosmic microwave background [CMB] to calculate the masses of enormous galaxy clusters using a new mathematical estimator.

    CMB per ESA/Planck

    This is the first time that scientists have measured these masses using the polarization of the CMB and the novel estimation method.

    “Making this estimate is important because most of the mass of galaxy clusters isn’t even visible – it’s dark matter, which does not emit light but interacts through gravity and makes up about 85% of the matter in our universe,” Benson said.

    The scientists’ work may eventually shed light on dark matter, dark energy and cosmological parameters that reveal more about structure formation in the universe.

    1
    The camera on the South Pole Telescope measures minuscule fluctuations in the polarization of cosmic-microwave-background light across the southern sky. Photo: Jason Gallicchio, University of Chicago

    Destination: Antarctica

    At Amundsen-Scott South Pole Station, support staff and scientists, nicknamed “beakers,” work around the clock to manage the South Pole Telescope. It’s not easy work. Amundsen-Scott South Pole Station is located at the southernmost place on Earth, where the average temperature is minus 47 degrees Celsius and the sun rises and sets only once a year. But the South Pole Telescope, a 10-meter telescope charged with observing the cosmic microwave background, known as the CMB, is more than capable of achieving its scientific goals in this harsh environment.

    The camera on the South Pole Telescope measures minuscule fluctuations in the polarization of CMB light across the southern sky on the order of 1 part in 100 million on average, more sensitive than any other experiment to date.

    “These minuscule variations can be affected by large objects such as galaxy clusters, which act as lenses that create distinctive distortions in our signal,” Benson said.

    The signal Benson and other scientists were looking for was a small-scale ripple around galaxy clusters — an effect called gravitational lensing. You can see a similar effect yourself by looking through the base of a clear wine glass behind which a candle is lit.

    “If you look through the bottom of a wine glass base at a flame, you can see a ring of light. That’s like the effect we would see from a strong gravitational lens,” Benson said.

    2
    Scientists look for small-scale ripple around galaxy clusters — an effect called gravitational lensing. The lensing is similar to the effect you would see looking through the base of a clear wine glass behind which a candle is lit — a ring of light. Image: Sandbox Studio

    Gravitational Lensing NASA/ESA

    “We are seeing a similar effect here, except the distortion is much weaker and the CMB light is spread out over a much larger area on the sky.”

    There was a problem, however. Scientists estimated they would need to look at around 17,000 galaxy clusters to measure the gravitational lensing effect from the CMB and estimate galaxy cluster masses with any certainty, even using their new mathematical estimator. While the South Pole Telescope provided deeper and more sensitive measurements of the CMB’s polarization than ever before, its library of galaxy locations contained only about 1,000 galaxy clusters.

    Destination: Chile

    To identify more galaxy cluster locations from which to examine the gravitational lensing of CMB light around galaxy clusters, the scientists needed to travel roughly 6,000 kilometers north of the South Pole to the Atacama region of Chile, home to the Cerro Tololo Inter-American Observatory.

    Cerro Tololo Inter-American Observatory on Cerro Tololo in the Coquimbo Region of northern Chile Altitude 2,207 m (7,241 ft)

    The Dark Energy Camera, mounted 2,200 meters above sea level on the 4-meter Blanco telescope at Cerro Tololo, is one of the largest digital cameras in the world. Its 520 megapixels see light from objects originating billions of light-years away and capture them in unprecedented quality. Most importantly, the camera captures the light and locations of the 17,000 galaxy clusters scientists needed to observe gravitational lensing of CMB light by galaxy clusters.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    The scientists identified the locations of these clusters using three years’ worth of data from the Fermilab-led Dark Energy Survey and then put these locations into a computer program that searched for evidence of gravitational lensing by the clusters in the polarization of the CMB. Once evidence was found, they could calculate the masses of the galaxy clusters themselves using their new mathematical estimator.

    Destination: Unspoiled places

    In the current study, the scientists found the average galaxy cluster mass to be around 100 trillion times the mass of our sun, an estimate that agrees with other methods. A substantial fraction of this mass is in the form of dark matter.

    To probe deeper, the scientists plan to perform similar experiments using an upgraded South Pole Telescope camera, SPT-3G, installed in 2017, and a next-generation CMB experiment, CMB-S4, that will offer further improvements in sensitivity and more galaxy clusters to examine.

    CMB-S4 will consist of dedicated telescopes equipped with highly sensitive superconducting cameras operating at the South Pole, the Chilean Atacama plateau and possibly northern-hemisphere sites, allowing researchers to constrain the parameters of inflation, dark energy and the number and masses of neutrinos, and even test general relativity on large scales.

    Anthony Bourdain, a gifted storyteller and food writer, once called Antarctica “the last unspoiled place on Earth … where people come together to explore the art of pure science, looking for something called facts.”

    Scientists go far beyond Antarctica to another unspoiled place, the farthest reaches of our universe, to grapple with fundamental cosmological parameters and the behavior of structure in our universe.

    See the full here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 9:51 am on January 5, 2020 Permalink | Reply
    Tags: Analysis of data from hundreds of supernovas—the stellar explosions that provided the first evidence for cosmic acceleration, , , , , Dark Energy, ,   

    From WIRED: “Does Dark Energy Really Exist? Cosmologists Battle It Out” 

    Wired logo

    From WIRED

    December 17, 2019
    Natalie Wolchover

    1
    The supernova SN 2007af shines clearly near the lower-right edge of the spiral galaxy NGC 5584. ESO

    Dark energy, mysterious as it sounds, has become part of the furniture in cosmology. The evidence that this repulsive energy infuses space has stacked up since 1998. That was the year astronomers first discovered that the expansion of the universe has been speeding up over time, with dark energy acting as the accelerator. As space expands, new space arises, and with it more of this repulsive energy, causing space to expand even faster.

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex Mittelmann Cold creation

    Saul Perlmutter [The Supernova Cosmology Project] shared the 2006 Shaw Prize in Astronomy, the 2011 Nobel Prize in Physics, and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt and Adam Riess [The High-z Supernova Search Team] for providing evidence that the expansion of the universe is accelerating.

    Two decades later, multiple independent measurements agree that dark energy comprises about 70 percent of the universe’s contents. It is so baked into our current understanding of the cosmos that it came as a surprise when a recent paper published in the journal Astronomy & Astrophysics questioned whether it’s there at all.

    The four authors, including the Oxford physicist Subir Sarkar, performed their own analysis of data from hundreds of supernovas—the stellar explosions that provided the first evidence for cosmic acceleration, a discovery that earned three astronomers the 2011 Nobel Prize in Physics. When Sarkar and his colleagues looked at supernovas, they didn’t see a universe that’s accelerating uniformly in all directions due to dark energy. Rather, they say supernovas look the way they do because our region of the cosmos is accelerating in a particular direction—roughly toward the constellation Centaurus in the southern sky.

    Standard Candles to measure age and distance of the universe from supernovae NASA

    Outside experts almost immediately began picking the paper apart, finding apparent flaws in its methodology. Now, two cosmologists have formalized those arguments and others in a paper that was posted online on December 6 and submitted to The Astrophysical Journal. The authors, David Rubin and his student Jessica Heitlauf of the University of Hawaii, Manoa, detail four main problems with Sarkar and company’s data handling. “Is the expansion of the universe accelerating?” their paper title asks. “All signs still point to yes.”

    Outside researchers praised the thorough dissection. “The arguments by Rubin et al. are very convincing,” said Dragan Huterer, a cosmologist at the University of Michigan. “Some of them I was aware of upon looking at the original [Astronomy & Astrophysics paper], and others are new to me but make a lot of sense.”

    However, Sarkar and his co-authors—Jacques Colin and Roya Mohayaee of the Paris Institute of Astrophysics and Mohamed Rameez of the University of Copenhagen—don’t agree with the criticisms. Days after Rubin and Heitlauf’s paper appeared, they posted a rebuttal of the rebuttal.

    The cosmology community remains unmoved. Huterer said this latest response at times “misses the point” and attempts to debate statistical principles that are “not negotiable.” Dan Scolnic, a supernova cosmologist at Duke University, reaffirmed that “the evidence for dark energy from supernovas alone is significant and secure.”

    A Moving Shot

    The expansion of space stretches light, reddening its color. Supernovas appear more “redshifted” the farther away they are, because their light has to travel farther through expanding space. If space expanded at a constant rate, a supernova’s redshift would be directly proportional to its distance, and thus to its brightness.

    But in an accelerating universe filled with dark energy, space expanded less quickly in the past than it does now. This means a supernova’s light will have stretched less during its long journey to Earth, given how slowly space expanded during much of the time. A supernova located at a given distance away (indicated by its brightness) will appear significantly less redshifted than it would in a universe without dark energy. Indeed, researchers find that the redshift and brightness of supernovas scales in just this way.

    3
    Illustration: Dillon Brout

    In their recent paper, Sarkar and collaborators took an unconventional approach to the analysis. Normally, any study of supernova data has to account for Earth’s movement: As Earth orbits the sun, which orbits the galaxy, which orbits the local group of galaxies, we and our telescopes hurtle through space at around 600 kilometers per second. Our net motion is toward a dense region near Centaurus. Consequently, light coming from that direction is subject to the Doppler shift, which makes it look bluer than the light from the opposite side of the sky.

    It’s standard to correct for this motion and to transform supernova data into a stationary reference frame. But Sarkar and company did not. “If you don’t subtract that [motion], then it puts the same Doppler shift into the supernova data,” Rubin explained in an interview. “Our claim is that most of the effect is due to the solar system’s motion.”

    Another problem with the paper, according to Rubin and Heitlauf, is that Sarkar and colleagues made a “plainly incorrect assumption”: They failed to account for the fact that cosmic dust absorbs more blue light than red.

    Because of this, a supernova in a relatively “clean,” dust-free region looks especially blue, since there’s less dust that would otherwise absorb its blue light. The lack of dust also means that it will appear brighter. Thus, the faraway supernovas we spot with our telescopes are disproportionately blue and bright. If you don’t control for the color-dependent effect of dust, you will infer less difference between the brightness of nearby supernovas (on average, dustier and redder) and faraway supernovas (on average, bluer and brighter)—and as a result, you will infer less cosmic acceleration.

    The combination of these and other unusual decisions allowed Sarkar’s group to model their supernova data with a “dipole” term, an acceleration that points in a single direction, and only a small, or possibly zero, “monopole” term describing the kind of uniform acceleration that signifies dark energy.

    This dipole model has two other problems, said Rubin and Heitlauf. First, the model includes a term that says how quickly the dipole acceleration drops to zero as you move away from Earth; Sarkar and company made this distance small, which means that their model isn’t tested by a large sampling of supernovas. And second, the model doesn’t satisfy a consistency check involving the relationship between the dipole and monopole terms in the equations.

    Not All the Same

    The day Rubin and Heitlauf’s paper appeared, Sarkar said by email, “We do not think any revisions need to be made to our analysis.” He and his team soon posted their rebuttal of the duo’s four points, mostly rehashing earlier justifications. They cited research by Natallia Karpenka, a cosmologist who has left academia for a career in finance, to support one of their choices, but they misconstrued her work, Rubin said. Four other cosmologists contacted by Quanta said the group’s response doesn’t change their view.

    Those who find the back-and-forth about data analysis hard to follow should note that the data from supernovas matches other evidence of cosmic acceleration. Over the years, dark energy has been inferred from the ancient light called the cosmic microwave background, fluctuations in the density of the universe called baryon acoustic oscillations, the gravitationally distorted shapes of galaxies, and the clustering of matter in the universe.

    Sarkar and colleagues ground their work in a respectable body of research on the “cosmological fitting problem.” Calculations of cosmological parameters like the density of dark energy (which is represented in Albert Einstein’s gravity equations by the Greek letter lambda) tend to treat the universe as smooth, averaging over the universe’s inhomogeneities, such as its galaxies and voids. The fitting problem asks whether this approximation might lead to incorrect inferences about the values of constants like lambda, or if it might even suggest the presence of a lambda that doesn’t exist.

    But the latest research on the question—including a major cosmological simulation published this summer—rejects that possibility. Inhomogeneities “could change lambda by 1 or 2 percent,” said Ruth Durrer of the University of Geneva, a co-author on that paper, “but could not get rid of it. It’s simply impossible.”

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
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