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

    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 2:24 pm on January 16, 2020 Permalink | Reply
    Tags: , , , , Dark Matter, , , The LSST Vera C. Rubin Observatory,   

    From The Kavli Foundation: “Behold the Whole Sky” The LSST Vera C. Rubin Observatory 

    KavliFoundation

    From The Kavli Foundation

    01/02/2020
    Adam Hadhazy

    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.

    The LSST Vera C. Rubin Observatory

    LSST Camera, built at SLAC



    LSST telescope, 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

    When construction is complete, the LSST, Vera C. Rubin Observatory, will be “the widest, fastest, deepest eye of the new digital age.”

    There’s about to be a new telescope in town—in the figurative sense, that is, unless you happen to literally live more than a mile-and-a-half up on the summit of a mountain named Cerro Pachón in the foothills of the Chilean Andes.

    There, construction is humming along for the Large Synoptic Survey Telescope, or LSST. Slated to start science operations early next decade, LSST in all likelihood will be a gamechanger for astronomy and astrophysics.

    What makes LSST so special is how big and fast it will be compared to other telescopes. “Big” in this case refers to the telescope’s field of view, which captures a chunk of sky 40 times the size of the full Moon. “Big” also refers to LSST’s mirror size, a very respectable 8.4 meters in diameter, which means it can collect ample amounts of cosmic light. Thirdly, “big” applies to LSST’s 3.2 billion-pixel camera, the biggest digital camera ever built. Put all those bits together, and LSST will be able to record images of significantly fainter and farther-away objects than other ground-based optical telescopes.

    And finally, as for “fast,” LSST will soak up more than 800 panoramas each night, cumulatively scanning the entire sky twice per week. That means the telescope will catch sight of fleeting astrophysical events, known as transients, that are often missed because telescopes—even today’s state-of-the-art, automated networks of ‘scopes—are not gobbling up so much of the sky so quickly. Transients that last days, weeks, and months—for instance, cataclysmic stellar explosions called supernovae—are routinely spotted. But the shortest events, lasting mere hours or even minutes, are another, untold story.

    “Unfortunately, we still know relatively little about the transient optical sky because we have never before had a survey that can make observations of a very large fraction of the sky repeatedly every few nights,” says Steven Kahn, Director of the LSST project. “LSST will meet this need.”

    Kahn, the Cassius Lamb Kirk Professor in the Natural Sciences and Professor of Particle Physics and Astrophysics at Stanford University, is also a member of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). He stepped into the director role back in 2013 when LSST was on the drawing board. Now the huge instrument is nearing the completion of its construction. Kahn and his colleagues are dearly looking forward to all that LSST will bring to the table, building on the pioneering work into gauging the transient sky underway with other, precursor projects worldwide.

    “LSST will go significantly deeper and cover the sky more rapidly,” says Kahn. “By covering more sky per unit time, we are more sensitive to very rare events, which are often the most interesting.”

    In this way, LSST is going to open up a major discovery space, for phenomena both (poorly) known and (entirely) unknown.

    “The Universe is far from static,” says Kahn. “There are stellar explosions of many different kinds that allow stars to brighten dramatically and then fade away on different timescales.” Some of these transient flashes of light are expected from the vicinities of neutron stars and black holes as they interact with matter that strays too close. Researchers hope to gain new insights into these dense objects’ properties, whose extreme physics challenge our best-supported theories.

    Another primary goal for LSST is to advance our understanding of the “dark universe” of dark matter and dark energy. Together, these entities compose 95 percent of the cosmos, with the “normal” matter that makes up stars, planets, and people registering as the remaining rounding error. Yet scientists have only stabs in the dark, as it were, on what exactly dark matter and dark energy really are. LSST will help by acquiring images of billions of galaxies, stretching back to some of the earliest epochs in the universe. Analyzing the shapes and distributions of these galaxies in space as well as time (recall that the farther away you see something in the universe, the farther you’re seeing back in time) will better show dark matter’s role in building up cosmic structure. The signature of dark energy, a force that is seemingly accelerating the universe’s expansion, will also be writ across the observed eons of galactic loci.

    Closer to home, LSST will vastly expand our knowledge of our own Solar System. It will take a census of small bodies, such as asteroids and comets, that fly by overhead, too faint for us humans to notice but there all the same—and in rare instances, potentially dangerously so; just ask the dinosaurs.

    “LSST will measure everything that moves in the sky,” says Kahn. “Of particular interest, we will provide the most complete catalogue of potentially hazardous asteroids, those objects whose orbits might allow them to impact the Earth.”

    Not done yet, LSST will also extend our catalogue of stars in the galaxy, aiding in charting the history and evolution of our own Milky Way galaxy. Furthermore, LSST will be a premier instrument for discovering the sources of gravitational waves, the ripples in spacetime first predicted by Albert Einstein in 1915 and finally directly detected in 2015 by the LIGO experiment. It can be a tough business today, even with the rich array of telescopes in operation, to rapidly pinpoint the visible light that gravitational wave-spawning neutron star collisions give off. LSST should aid in that regard admirably.

    The wait is nearly over. The LSST building is nearly complete, the large mirrors are on site, and the camera is being integrated at the at SLAC National Accelerator Laboratory in California, which co-hosts KIPAC along with Stanford.

    “Basically, everything that needed to be fabricated for the LSST telescope and camera has been fabricated,” says Kahn. “The remaining work largely involves putting the system together and getting it working.”

    Kahn has been to the telescope site recently, in both September and October. He likes what he sees.

    “Visiting the site in Chile is a remarkable experience,” Kahn says. “It is a beautiful site, and the LSST facility sits prominently atop the edge of a cliff on Cerro Pachón. The sheer size of the building and its complexity is striking.”

    Before long, the impressiveness of the building will recede into the background as the profundity of the science LSST generates takes center stage.

    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 1:07 pm on January 14, 2020 Permalink | Reply
    Tags: A pursuit that stretches from underground particle colliders to orbiting telescopes with all manner of ground-based observatories in between., , , , , , Dark Matter, , , , The astronomer missed her Nobel Prize [in my view a crime of old white men], ,   

    From The New York Times: Women in STEM-“Vera Rubin Gets a Telescope of Her Own” 

    From The New York Times

    Jan. 11, 2020
    Dennis Overbye

    The astronomer missed her Nobel Prize [in my view a crime of old white men]. But she now has a whole new observatory to her name.

    1
    The astronomer Vera Rubin at the Lowell Observatory in Flagstaff, Ariz., in 1965.Credit: via Carnegie Institution of 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.

    Vera Rubin, a young astronomer at the Carnegie Institution in Washington, was on the run in the 1970s when she overturned the universe.

    Seeking refuge from the controversies and ego-bashing of cosmology, she decided to immerse herself in the pearly swirlings of spiral galaxies, only to find that there was more to them than she and almost everybody else had thought.

    For millenniums, humans had presumed that when we gaze out at the universe, what we see is a fair representation of reality. Dr. Rubin, with her colleague Kent Ford, discovered that was not true. The universe — all those galaxies and the vast spaces between — was awash with dark matter, an invisible something with sufficient gravity to mold the large scale structures of the universe.

    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.

    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed by Vera Rubin

    Esteemed astronomers dismissed her findings at first. But half a century later, the still futile quest to identify this “dark matter” is a burning question for both particle physics and astronomy. It’s a pursuit that stretches from underground particle colliders to orbiting telescopes, with all manner of ground-based observatories in between.

    Last week the National Science Foundation announced that the newest observatory joining this cause will be named the Vera C. Rubin Observatory. The name replaces the mouthful by which the project was previously known: the Large Synoptic Survey Telescope, or L.S.S.T.

    2
    The Vera C. Rubin Observatory, formerly the Large Synoptic Survey Telescope, under construction in Cerro Pachon, Chile. Credit: LSST Project/NSF/AURA

    The Rubin Observatory joins a handful of smaller astronomical facilities that have been named for women. The Maria Mitchell Observatories in Nantucket, Mass., is named after the first American woman to discover a comet. The Swope telescope, at Carnegie’s Las Campanas Observatory in Chile, is named after Henrietta Swope, who worked at the Harvard College Observatory in the early 20th century. She used a relationship between the luminosities and periodicities of variable stars to measure distances to galaxies.

    And finally there is the new Annie Maunder Astrographic Telescope at the venerable Royal Greenwich Observatory, just outside London. It is named after Annie Maunder, who with her husband Walter made pioneering observations of the sun and solar cycle of sunspots in the late 1800s.

    Heros of science, all of them.

    In a field known for grandiloquent statements and frightening intellectual ambitions, Dr. Rubin was known for simple statements about how stupid we are. In an interview in 2000 posted on the American Museum of Natural History website, Dr. Rubin said:

    “In a spiral galaxy, the ratio of dark-to-light matter is about a factor of 10. That’s probably a good number for the ratio of our ignorance to knowledge. We’re out of kindergarten, but only in about third grade.”

    Once upon a time cosmologists thought there might be enough dark matter in the universe for its gravity to stop the expansion of the cosmos and pull everything back together in a Big Crunch. Then astronomers discovered an even more exotic feature of the universe, now called dark energy, which is pushing the galaxies apart and speeding up the cosmic expansion.

    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.

    These discoveries have transformed cosmology still further, into a kind of Marvel Comics super-struggle between invisible, titanic forces. One, dark matter, pulls everything together toward its final doom; the other, dark energy, pushes everything apart toward the ultimate dispersal, some times termed the Big Rip. The rest of us, the terrified populace looking up at this cosmic war, are bystanders, made of atoms, which are definitely a minority population of the universe. Which force will ultimately prevail? Which side should we root for?

    Until recently the money was on dark energy and eventual dissolution of the cosmos. But lately cracks have appeared in the data, suggesting that additional forces may be at work beneath the surface of our present knowledge.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 8:36 pm on January 13, 2020 Permalink | Reply
    Tags: , , , Calculate the masses of enormous galaxy clusters using a new mathematical estimator., , , , Dark Matter, 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.


    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 9:24 am on January 7, 2020 Permalink | Reply
    Tags: , , , , Dark Matter, , , ,   

    From Symmetry: Women in STEM -“Vera Rubin, giant of astronomy” 

    Symmetry Mag
    From Symmetry<

    01/07/20
    Kathryn Jepsen

    1
    Illustration by Sandbox Studio, Chicago with Ana Kova

    The Large Synoptic Survey Telescope will be named for an influential astronomer who left the field better than she found it.

    The LSST Vera C. Rubin Observatory

    LSST telescope, Vera C. Rubin Observatory 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

    The Large Synoptic Survey Telescope, a flagship astronomy and astrophysics project currently under construction on a mountaintop in Chile, will be named for astronomer Vera Rubin, a key figure in the history of the search for 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.

    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

    The LSST collaboration announced the new name at the 235th American Astronomical Society meeting in Honolulu on Monday evening, in conjunction with US funding agencies the Department of Energy and the National Science Foundation.

    Scheduled to begin operation in late 2022, the Vera C. Rubin Observatory will undertake a decade-long survey of the sky using an 8.4-meter telescope and a 3200-megapixel camera to study, among other things, the invisible material Rubin is best known for bringing into the realm of accepted theory.

    Rubin was a role model, a mentor, and a boundary-breaker fueled by a true love of science and the stars. “For me, doing astronomy is incredibly great fun,” she said in a 1989 interview with physicist and writer Alan Lightman. “It’s just an incredible joy to get up every morning and come to work and, in some much larger framework, not even really quite know what it is I’m going to be doing.”

    Between the Lightman interview and An Interesting Voyage, a biography she wrote in 2010 for the Annual Review of Astronomy and Astrophysics, among other things, she left behind a detailed record of the story of her life.

    A curious child

    Rubin’s father, Pesach Kobchefski (later known as Philip Cooper), was born in Lithuania. Her mother, Rose Applebaum, was a second-generation American born to Bessarabian parents in Philadelphia. Rubin’s parents met at work at the Bell Telephone Company. They married and raised two children, Vera and her older sister, Ruth.

    Rubin was born in 1928. She wrote that she remembered growing up “amid a cheery scatter of grandparents, aunts, uncles and cousins… largely shielded from the financial difficulties” of the Great Depression. Ruth and Vera shared a room, with Vera’s bed against a window with a clear view of the north sky. “Soon it was more interesting to watch the stars than to sleep,” Rubin wrote.

    Her parents encouraged her curiosity. Her mother gave her written permission at an early age to check out books from the “12 and over” section of the library, and her father helped her build a (rather so-so) homemade telescope. “My parents were very, very supportive,” Rubin said in the interview with Lightman, “except that they didn’t like me to stay up all night.”

    Rubin’s teachers were not universally as encouraging. Her high school physics teacher, she wrote, “did not know how to include the few young girls in the class, so he chose to ignore us.” Still, Rubin knew she wanted to go into astronomy. “I didn’t know a single astronomer,” she said, “but I just knew that was what I wanted to do.”

    She did know about at least one female astronomer: Maria Mitchell, the first female professional astronomer in the United States. From 1865 to 1888, Mitchell taught at Vassar College in New York and served as director of Vassar College Observatory.

    Looking to follow in her footsteps, Rubin applied to Vassar. She was accepted with a necessary scholarship. Rubin said that when she told the high school physics teacher about it, he replied, “‘As long as you stay away from science, you should be okay.’”

    She graduated in three years as the only astronomy major in her class.

    A family effort

    Rubin spent summers in Washington, DC, working at the Naval Research Laboratory. The summer of 1947, her parents introduced her to Robert (Bob) Rubin. He was training to be an officer in the US Navy and studying chemistry at Cornell University.

    The two married in 1948. She was 19 and he was 21. Vera had been accepted to Harvard University, which was well known for its astronomy department, but she decided to join her husband at Cornell instead.

    Rubin completed her master’s thesis just before giving birth to her first child, and she gave a talk on her research at the 1950 meeting of the American Astronomical Society just after. Her adviser had said it made more sense for him to give the talk, as he was already a member of AAS and she would be a new mother, but Rubin insisted she would do it.

    “We had no car,” Rubin wrote. “My parents drove from Washington, DC, to Ithaca, then crossed the snowy New York hills with Bob, me and their first grandchild, ‘thereby aging 20 years,’ my father later insisted.”

    She gave a 10-minute talk on her study of the velocity distribution of the galaxies that at that time had published velocities. It solicited replies from several “angry-sounding men,” along with pioneering astronomer Martin Schwarzschild, who, Rubin wrote, kindly “said what you say to a young student: ‘This is very interesting, and when there are more data, we will know more.’”

    For a few months after the experience, Rubin stayed home with her newborn son. But she couldn’t keep away from the science. “I would push David to the playground, sit him in the sandbox, and read The Astrophysical Journal,” Rubin wrote.

    With her husband’s encouragement, she enrolled in the astronomy PhD program at Georgetown University. Her classes took place at night, twice per week. Those nights, between 1952 and 1954, Rubin’s mother babysat David (and, not long after, also her daughter, Judy) while Bob drove her to the observatory and waited to take her back home, eating his dinner in the car. In astronomy, “women generally required more luck and perseverance than men did,” Rubin wrote. “It helped to have supportive parents and a supportive husband.”

    PhD and beyond

    Theoretical physicist and cosmologist George Gamow—known for his contributions to developing the Big Bang theory, among other foundational work—heard about Rubin’s AAS talk and began asking her questions, Rubin wrote. One question—“Is there a scale length in the distribution of galaxies?”—so intrigued her that she decided to take it on for her thesis. Gamow served as her advisor.

    Rubin wrote that when she sent her research to The Astrophysical Journal in 1954, then-editor and later Nobel Laureate Subrahmanyan Chandrasekhar rejected it, saying he wanted her to wait until his student finished his work on the same subject. She did not wait, publishing in the Proceedings of the National Academy of Sciences instead. (A later editor of Astrophysical Journal asked her to send him Chandrasekhar’s letter as proof, and she wrote, “I refused, telling him to look it up in his files.”)

    In 1955, Georgetown offered Rubin a research position, which soon became a teaching position as well. She stayed there for 10 years.

    In 1962, Rubin taught a graduate course in statistical astronomy with six students, five who worked for the US Naval Observatory and one who worked for NASA. “Due to their jobs, the students were experts in star catalogs,” Rubin wrote, “so I gave the students (plus me as a student) a research problem: Can we use cataloged stars to determine a rotation curve for stars distant from the center of our [g]alaxy?”

    The group completed the paper, “some of it finished by seven of us working around my large kitchen table, long into the night,” Rubin wrote, and they submitted it to The Astrophysical Journal.

    The editor called to say he would accept the paper but that he would not take the then-unusual step of publishing the names of the students, Rubin wrote. When Rubin replied that she would then withdraw the paper, however, he changed his mind.

    Rubin wrote that she received many negative “and some very unpleasant” responses to the paper, but that it continued to be referenced every few years, even as she was writing in 2010. As she pointed out in her article, “[t]his was my first flat rotation curve”—a result she would see repeated in what would become her most famous publication.

    During the 1963-1964 school year, Bob took a sabbatical so Vera could move the family to San Diego and work with married couple Margaret and Geoffrey Burbidge. With two other scientists, they had in 1957 published the seminal paper explaining how thermonuclear reactions in stars could transform a universe originally made up only of hydrogen, helium and lithium into one that could support life. With the Burbidges, Rubin traveled to both Kitt Peak National Observatory in Arizona and McDonald Observatory in Texas.

    More than three decades later, in letter to Margaret Burbidge on her 80th birthday, Rubin described what the scientist had meant to her: “Did the words ‘role model’ and ‘mentor’ exist then? I think they did not. But for most of the women that followed you into astronomical careers, these were the roles you filled for us.”

    What Rubin best remembers from when she first arrived in San Diego, she wrote, “was my elation because you took me seriously and were interested in what I had to say…

    “From you we have learned that a woman too can rise to great heights as an astronomer, and that it’s all right to be charming, gracious, brilliant, and to be concerned for others as we make our way in the world of science.”

    The view from Palomar

    Caltech Palomar Hale Telescope, located in San Diego County, California, US, at 1,712 m (5,617 ft)

    In 1964, Rubin and her family (which now included four children, between ages 4 and 13) returned home. Shortly thereafter, Vera and Bob took off again for the meeting of the International Astronomical Union in Hamburg. (“Fortunately, my parents enjoyed being with their grandchildren,” Rubin wrote.)

    On the last evening of the conference, influential astronomer Allan Sandage, who in 1958 had published the first good estimate of the Hubble constant, asked Rubin if she were interested in observing on Palomar Mountain at the Carnegie Institution’s 200-inch telescope. It was a telescope, located on a mountain northeast of San Diego, that women had officially been prohibited from using (though it was a “known secret” that both Margaret and Geoffrey Burbidge had observed there together as postgraduate students). “Of course, I said yes,” Rubin wrote.

    Rubin would be observing on the same mountain where, in 1933, astronomer Fritz Zwicky [above] made a startling discovery. He noticed that the galaxies in the Coma Cluster were moving too quickly—so quickly that they should have broken apart. Judging by the mass of their visible matter, they should not have had the gravitational pull to hold together.

    He concluded that the cluster must be more massive than it appeared, and that most of this mass must come from matter that could not be seen. The Swiss astronomer called the source of the missing mass dunkle Materie, or dark matter. He presented this idea to the Swiss Physical Society, but it did not catch on. (He made several other big splashes in astronomy, though.)

    On Rubin’s first night at Palomar in December 1965, clouds prevented anyone from observing, so another observer took her on an unofficial tour of the facilities. The tour included the single available toilet, labeled “MEN.”

    On Rubin’s next visit, “I drew a skirted woman and pasted her up on the door,” she wrote. The third time she came to observe, heating had been added to the observing room, along with a gender-neutral bathroom.

    The world’s best spectrograph

    In 1965, Rubin decided to prioritize observing over teaching. She asked her colleague Bernie Burke—famous for co-discovering the first detection of radio noise from another planet, Jupiter—for a job at the Carnegie Institution’s Department of Terrestrial Magnetism. Burke invited her to the DTM’s community lunch. And that’s where she met astronomer Kent Ford.

    Working over the previous decade, Ford had pioneered the use of highly sensitive light detectors called photomultiplier tubes for astronomical observation. “Kent Ford had built a very exceptional spectrograph,” Rubin said. “He probably had the best spectrograph anywhere. He had a spectrograph that could do things that no other spectrographs could do.”

    Rubin got the job at DTM, becoming the first female scientist on its staff. Using Ford’s spectrograph on the telescope at Lowell Observatory in Arizona [above], Ford and Rubin could observe objects that were not otherwise detectable. Among the astronomers who noticed was Jim Peebles, winner of the 2019 Nobel Prize for Physics.

    By 1968, Rubin and Ford had published nine papers. “It was an exciting time,” Rubin wrote, “but I was not comfortable with the very rapid pace of the competition. Even very polite phone calls asking me which galaxies I was studying (so as not to overlap) made me uncomfortable.”

    So she decided to go back to a subject she had previously dabbled in: the velocity of stars and regions of ionized hydrogen in Messier 31, the Andromeda galaxy. “I decided to pick a problem that I could go observing and make headway on, hopefully a problem that people would be interested in, but not so interested [in] that anyone would bother me before I was done,” Rubin said.

    Astronomers had been studying the spectra of light from Andromeda since at least January 1899, but no one had taken a look with an instrument as advanced as Ford’s.

    One astronomer had gotten a better look than most, though. In the 1940s, astronomer Walter Baade had taken advantage of wartime blackout rules—meant to make it difficult for enemy planes to hit targets during World War II—to observe Andromeda from Mount Wilson Observatory northeast of Los Angeles.


    Mt Wilson 100 inch Hooker Telescope, perched atop the San Gabriel Mountains outside Los Angeles, CA, USA, Mount Wilson, California, US, Altitude 1,742 m (5,715 ft)

    He resolved the stars at the center of the galaxy for the first time and identified 688 emission regions worthy of study.

    Not knowing this, Rubin and Ford set out to do the same for themselves. They spent a frustrating night taking turns at the US Naval Observatory telescope in Arizona, huddled next to a small heater in negative 20 degree cold, before deciding they needed a new tactic.

    2
    US Naval Observatory telescope in Arizona

    On their way out in the morning, they ran into Naval Observatory Director Gerald Kron. “He took us into his warm office, opened a large cabinet and showed us copies of Baade’s many plates of stars in Messier 31!” Rubin wrote. Rubin and Ford obtained copies of the images from the Carnegie Institute and went to work.

    A rotation curveball

    Rubin and Ford made their observations at Lowell Observatory[above] and Kitt Peak.

    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)

    “On a typical clear night we would obtain four to five spectra,” Rubin wrote. “The surprises came very quickly.”

    In our solar system, planets closest to the center are the fastest-moving, as they are most affected by the gravitational pull of the sun. Mercury, the closest, moves about 1.6 times as rapidly as Earth, whereas Neptune, the farthest, moves at less than 0.2 times Earth’s speed.

    “The expectation was that galaxies behaved the same way, in that stars farthest from the massive center would be moving most slowly,” Rubin wrote.

    But that’s not what they found. The rotation curves were flat, meaning that objects closer to the center of Andromeda were moving at the same speed as objects closer to the outskirts. “This was discovered over the course of about 4 ice cream cones that first night,” Rubin wrote, “as I alternated between developing the plates and eating (Kent would be starting the next observation).”

    This time, Rubin said, people believed the data. “It just piled up too fast. Soon there were 20, then 40, then 60 rotation curves, and they were all flat… And it was just a joy to have that kind of a program, after a program where you had to go through deep analysis and everybody doubted the answer.”

    But what did the flat rotation curves mean? The popularly accepted answer is that the way the galaxies in Andromeda move is influenced by dark matter.

    If a galaxy is formed in the center of a disk of invisible dark matter, the gravitational pull of the dark matter will affect how quickly each of its parts moves, flattening the rotation curves.

    Theorists Peebles, Jeremiah P. Ostriker, Amos Yahil and others had predicted the existence of dark matter independent of Rubin and Ford’s findings, Rubin said. “The ideas had been around for a while… But the observations fit in so well, [since] there was already a framework, so some people embraced the observations very enthusiastically.”

    Rubin was agnostic about the idea of dark matter and wrote that she would be delighted if the explanation actually came in the form of a new understanding of how gravity works on the cosmic scale. “One needs to keep an open mind in seeking solutions,” she wrote.

    A scientific legacy

    Rubin continued her work, receiving recognition for her contributions in various ways.

    From 1972 to 1977 she served as associate editor of The Astronomical Journal, and from 1977 to 1982 she served as associate editor of Astrophysical Journal Letters. In 1993, she received the National Medal of Science from President Bill Clinton. In 1994 she received the Dickson Prize in Science from Carnegie-Mellon University and the Henry Norris Russell Lectureship from the American Astronomical Society. In 1996 she became the second woman to receive the Gold Medal of the Royal Astronomical Society in London (168 years after the first, Caroline Herschel in 1828). In 1996 President Clinton nominated her to provide input to Congress as a member of the National Science Board for a term of six years.

    In 1997 she and a few other members of the board were invited to visit the McMurdo research station at the South Pole. Rubin wrote that she was asked if she would spend her time at McMurdo with the astronomers. “With a little embarrassment, I asked if that meant that I would miss everything else, the penguins, the mountains and all the other events,” she wrote. “Without much difficulty, I voted for the penguins.”

    In 2004 the National Academy of Sciences awarded Rubin the James Craig Watson Medal for “her seminal observations of dark matter in galaxies… and for generous mentoring of young astronomers, men and women.”

    Rubin made it a priority to listen to and encourage students and up-and-coming astronomers, and she was especially interested in improving the chances for women in science.

    Asked by Lightman, “Do you think that your experience in science has been different because you are a woman rather than a man?” she replied, “Of course. Yes, of course. But I’m the wrong person to ask that question. The tragedy in that question is all the women who would have liked to have become astronomers and didn’t.”

    Rubin shared her love of astronomy far and wide. “We are fortunate to live in an era when it is possible to learn so much about the [u]niverse,” she wrote. “But I envy our children, our grandchildren, and their children. They will know more than any of us do now, and they may even be able to travel there!”

    All four of the Rubin children have gone into science.

    Her son Allan, quoted in the 2010 article, remembered his parents often spent evenings “with their work spread out along the very long dining room table, which wasn’t used for eating unless a lot of company was expected,” he said. “At some point I grew old enough to realize that if what they really wanted to do after dinner was the same thing they did all day at work, then they must have pretty good jobs.”

    Rubin’s daughter followed Vera into the field of astronomy, initially hooked by a lesson her mother taught on black holes. Over several decades, Judy has collaborated on numerous publications and attended meetings around the world with her mom.

    Rubin died in 2016 at the age of 88. Her name lives on in the AAS Vera Rubin Early Career Prize, Vera Rubin Ridge on the planet Mars, Asteroid 5726 Rubin and, now, the Vera C. Rubin Observatory on Cerro Pachón

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:17 am on December 29, 2019 Permalink | Reply
    Tags: , , , Dark Matter, , , , ,   

    From particlebites: “Dark Photons in Light Places” 

    particlebites bloc

    From particlebites

    December 29, 2019
    Amara McCune

    Title: “Searching for dark photon dark matter in LIGO O1 data”

    Author: Huai-Ke Guo, Keith Riles, Feng-Wei Yang, & Yue Zhao

    Reference: https://www.nature.com/articles/s42005-019-0255-0

    There is very little we know about dark matter save for its existence.

    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.

    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

    Its mass(es), its interactions, even the proposition that it consists of particles at all is mostly up to the creativity of the theorist. For those who don’t turn to modified theories of gravity to explain the gravitational effects on galaxy rotation and clustering that suggest a massive concentration of unseen matter in the universe (among other compelling evidence), there are a few more widely accepted explanations for what dark matter might be. These include weakly-interacting massive particles (WIMPS), primordial black holes, or new particles altogether, such as axions or dark photons.

    In particle physics, this latter category is what’s known as the “hidden sector,” a hypothetical collection of quantum fields and their corresponding particles that are utilized in theorists’ toolboxes to help explain phenomena such as dark matter. In order to test the validity of the hidden sector, several experimental techniques have been concocted to narrow down the vast parameter space of possibilities, which generally consist of three strategies:

    1.Direct detection: Detector experiments look for low-energy recoils of dark matter particle collisions with nuclei, often involving emitted light or phonons.
    2.Indirect detection: These searches focus on potential decay products of dark matter particles, which depends on the theory in question.
    3.Collider production: As the name implies, colliders seek to produce dark matter in order to study its properties. This is reliant on the other two methods for verification.

    The first detection of gravitational waves from a black hole merger in 2015 ushered in a new era of physics, in which the cosmological range of theory-testing is no longer limited to the electromagnetic spectrum.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/NASA eLISA space based, the future of gravitational wave research

    Bringing LIGO (the Laser Interferometer Gravitational-Wave Observatory) to the table, proposals for the indirect detection of dark matter via gravitational waves began to spring up in the literature, with implications for primordial black hole detection or dark matter ensconced in neutron stars. Yet a new proposal, in a paper by Guo et. al., [Scientific Reports-Communication Physics] suggests that direct dark matter detection with gravitational waves may be possible, specifically in the case of dark photons.

    Dark photons are hidden sector particles in the ultralight regime of dark matter candidates. Theorized as the gauge boson of a U(1) gauge group, meaning the particle is a force-carrier akin to the photon of quantum electrodynamics, dark photons either do not couple or very weakly couple to Standard Model particles in various formulations. Unlike a regular photon, dark photons can acquire a mass via the Higgs mechanism. Since dark photons need to be non-relativistic in order to meet cosmological dark matter constraints, we can model them as a coherently oscillating background field: a plane wave with amplitude determined by dark matter energy density and oscillation frequency determined by mass. In the case that dark photons weakly interact with ordinary matter, this means an oscillating force is imparted. This sets LIGO up as a means of direct detection due to the mirror displacement dark photons could induce in LIGO detectors.

    3
    Figure 1: The experimental setup of the Advanced LIGO interferometer. We can see that light leaves the laser and is reflected between a few power recycling mirrors (PR), split by a beam splitter (BS), and bounced between input and end test masses (ITM and ETM). The entire system is mounted on seismically-isolated platforms to reduce noise as much as possible. Source: https://arxiv.org/pdf/1411.4547.pdf

    LIGO consists of a Michelson interferometer, in which a laser shines upon a beam splitter which in turn creates two perpendicular beams. The light from each beam then hits a mirror, is reflected back, and the two beams combine, producing an interference pattern. In the actual LIGO detectors, the beams are reflected back some 280 times (down a 4 km arm length) and are split to be initially out of phase so that the photodiode detector should not detect any light in the absence of a gravitational wave. A key feature of gravitational waves is their polarization, which stretches spacetime in one direction and compresses it in the perpendicular direction in an alternating fashion. This means that when a gravitational wave passes through the detector, the effective length of one of the interferometer arms is reduced while the other is increased, and the photodiode will detect an interference pattern as a result.

    LIGO has been able to reach an incredible sensitivity of one part in 10^{23} in its detectors over a 100 Hz bandwidth, meaning that its instruments can detect mirror displacements up to 1/10,000th the size of a proton. Taking advantage of this number, Guo et. al. demonstrated that the differential strain (the ratio of the relative displacement of the mirrors to the interferometer’s arm length, or h = \Delta L/L) is also sensitive to ultralight dark matter via the modeling process described above. The acceleration induced by the dark photon dark matter on the LIGO mirrors is ultimately proportional to the dark electric field and charge-to-mass ratio of the mirrors themselves.

    Once this signal is approximated, next comes the task of estimating the background. Since the coherence length is of order 10^9 m for a dark photon field oscillating at order 100 Hz, a distance much larger than the separation between the LIGO detectors at Hanford and Livingston (in Washington and Louisiana, respectively), the signals from dark photons at both detectors should be highly correlated. This has the effect of reducing the noise in the overall signal, since the noise in each of the detectors should be statistically independent. The signal-to-noise ratio can then be computed directly using discrete Fourier transforms from segments of data along the total observation time. However, this process of breaking up the data, known as “binning,” means that some signal power is lost and must be corrected for.

    4
    Figure 2: The end result of the Guo et. al. analysis of dark photon-induced mirror displacement in LIGO. Above we can see a plot of the coupling of dark photons to baryons as a function of the dark photon oscillation frequency. We can see that over further Advanced LIGO runs, up to O4-O5, these limits are expected to improve by several orders of magnitude. Source: https://www.nature.com/articles/s42005-019-0255-0

    In applying this analysis to the strain data from the first run of Advanced LIGO, Guo et. al. generated a plot which sets new limits for the coupling of dark photons to baryons as a function of the dark photon oscillation frequency. There are a few key subtleties in this analysis, primarily that there are many potential dark photon models which rely on different gauge groups, yet this framework allows for similar analysis of other dark photon models. With plans for future iterations of gravitational wave detectors, further improved sensitivities, and many more data runs, there seems to be great potential to apply LIGO to direct dark matter detection. It’s exciting to see these instruments in action for discoveries that were not in mind when LIGO was first designed, and I’m looking forward to seeing what we can come up with next!

    Learn More:

    An overview of gravitational waves and dark matter: https://www.symmetrymagazine.org/article/what-gravitational-waves-can-say-about-dark-matter
    A summary of dark photon experiments and results: https://physics.aps.org/articles/v7/115
    Details on the hardware of Advanced LIGO: https://arxiv.org/pdf/1411.4547.pdf
    A similar analysis done by Pierce et. al.: https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.121.061102

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    What is ParticleBites?

    ParticleBites is an online particle physics journal club written by graduate students and postdocs. Each post presents an interesting paper in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

    The papers are accessible on the arXiv preprint server. Most of our posts are based on papers from hep-ph (high energy phenomenology) and hep-ex (high energy experiment).

    Why read ParticleBites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.

    Our goal is to solve this problem, one paper at a time. With each brief ParticleBite, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in particle physics.

    Who writes ParticleBites?

    ParticleBites is written and edited by graduate students and postdocs working in high energy physics. Feel free to contact us if you’re interested in applying to write for ParticleBites.

    ParticleBites was founded in 2013 by Flip Tanedo following the Communicating Science (ComSciCon) 2013 workshop.

    2
    Flip Tanedo UCI Chancellor’s ADVANCE postdoctoral scholar in theoretical physics. As of July 2016, I will be an assistant professor of physics at the University of California, Riverside

    It is now organized and directed by Flip and Julia Gonski, with ongoing guidance from Nathan Sanders.

     
  • richardmitnick 12:49 pm on December 26, 2019 Permalink | Reply
    Tags: "Before There Were Stars", , Dark Matter, Molecular Hydrogen, , ,   

    From Nautilus: “Before There Were Stars” 

    Nautilus

    From Nautilus

    December 26, 2019
    Daniel Wolf Savin
    Illustration by Jon Han

    1

    The unlikely heroes that made starlight possible.

    The universe is the grandest merger story that there is. Complete with mysterious origins, forces of light and darkness, and chemistry complex enough to make the chemical conglomerate BASF blush, the trip from the first moments after the Big Bang to the formation of the first stars is a story of coming together at length scales spanning many orders of magnitude.

    ALMA Schematic diagram of the history of the Universe. The Universe is in a neutral state at 400 thousand years after the Big Bang, until light from the first generation of stars starts to ionise the hydrogen. After several hundred million years, the gas in the Universe is completely ionised. Credit. NAOJ

    To piece together this story, scientists have turned to the skies, but also to the laboratory to simulate some of the most extreme environments in the history our universe. The resulting narrative is full of surprises. Not least among these, is how nearly it didn’t happen—and wouldn’t have, without the roles played by some unlikely heroes. Two of the most important, at least when it comes to the formation of stars, which produced the heavier elements necessary for life to emerge, are a bit surprising: dark matter and molecular hydrogen. Details aside, here is their story.

    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

    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

    2

    Dark Matter

    The Big Bang created matter through processes we still do not fully understand. Most of it—around 84 percent by mass—was a form of matter that does not interact with or emit light. Called dark matter, it appears to interact only gravitationally. The remaining 16 percent, dubbed baryonic or ordinary matter, makes up the everyday universe that we call home.

    Standard Model of Particle Physics

    Ordinary matter interacts not only gravitationally but also electromagnetically, by emitting and absorbing photons (sometimes called radiation by the cognoscenti and known as light in the vernacular).

    As the universe expanded and cooled, some of the energy from the Big Bang converted into ordinary matter: electrons, neutrons, and protons (the latter are equivalent to ionized hydrogen atoms). Today, protons and neutrons comfortably rest together in the nuclei of atoms.

    The quark structure of the proton 16 March 2006 Arpad Horvath

    But in the seconds after the Big Bang, any protons and neutrons that fused to form heavier atomic nuclei were rapidly blown apart by high-energy photons called gamma rays. The residual thermal radiation field of the Big Bang provided plenty of those. It was too hot to cook. But things got better a few seconds later, when the radiation temperature dropped to about a trillion degrees Kelvin—still quite a bit hotter than the 300 Kelvin room temperature to which we are accustomed, but a world of difference for matter in the early universe.

    Heavier nuclei could now survive the gamma-ray bombardment. Primordial nucleosynthesis kicked in, enabling nuclear forces to bind protons and neutrons together, until the expansion of the universe made it too cold for these fusion reactions to continue. In these 20 minutes, the universe was populated with atoms. The resulting elemental composition of the universe weighed in at roughly 76 percent hydrogen, 24 percent helium, and trace amounts of lithium—all ionized, since it was too hot for electrons to stably orbit these nuclei. And that was it, until the first stars formed and began to forge all the other elements of the periodic table.

    Before these stars could form, however, newly-formed hydrogen and helium atoms needed to gather together to make dense clouds. These clouds would have been produced when slightly denser regions of the universe gravitationally attracted matter from their surroundings. The question is, was the early universe clumpy enough for this to have happened?

    To answer the question, we can look to the modern-day night sky. In it, we see a faint glow of microwave radiation that has an even fainter pattern in it. This so-called cosmic microwave background [CMB] structure dates back to 377,000 years after the Big Bang, a mere fraction of the universe’s current age of 13.8 billion years, and analogous to less than a day in the 81-year life expectancy for a woman living today in the United States.

    CMB per ESA/Planck

    At that time, the universe had just cooled to about 3,000 Kelvin. Free electrons started to be captured into orbit around protons, forming neutral hydrogen atoms. Photons from the flash of the Big Bang, whose progress had been impeded by their scattering off of unbound electrons, could now finally stream throughout the cosmos, essentially free. These photons continue to permeate the universe today, at a frigid temperature of only 2.7 Kelvin, and constitute the cosmic microwave background that we have measured using an array of ground-based, balloon-born, and satellite telescopes.

    These sky maps suggested something surprising: The intensity of the residual heat from the Big Bang made the early universe too smooth for gas clouds to form.

    Enter dark matter [above]. Because it does not interact directly with light, it was unaffected by the same radiation that smoothed out ordinary matter. Therefore it was left with a relatively high degree of clumpiness. It, rather than regular matter, initiated the formation of the stars and galaxies that make up the modern structure of the universe. Regions of space with an above-average density of dark matter gravitationally attracted matter from regions with lower densities. Halos of dark matter formed and merged with other halos, bringing ordinary matter along for the ride.

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

    4

    Molecular Hydrogen

    Once the universe went neutral, gas began to form into clouds. As ordinary matter accelerated into the gravitational wells of dark matter, gravitational potential energy converted into kinetic energy, creating a hot gas of fast-moving particles with high kinetic energies embedded within halos of dark matter. Starting from temperatures around 1,000 Kelvin, these gas clouds eventually gave birth to the first stars when the universe was roughly half a billion years old (about four years into the lifespan of the typical U.S. woman).

    For a star to form, a gas cloud needs to reach a certain density; but if its constituent molecules are too hot, zipping around in every direction, this density may be unreachable. The first step toward making star-forming clouds was for gas atoms to slow down by radiating their kinetic energy out of the cloud and into the larger universe, which by this time had cooled to below 100 Kelvin.

    But they can’t cool themselves: As atoms collide like billiard balls, they exchange kinetic energy. But the total kinetic energy of the gas remains unchanged. They needed a catalyst to cool off.

    This catalyst was molecular hydrogen (two hydrogen atoms bound together by sharing their electrons). Hot particles colliding with this dumbbell-shaped molecule transferred some of their own energy to the molecule, causing it to rotate. Eventually these excited hydrogen molecules would relax back to their lowest-energy (or ground) state by emitting a photon that escaped from the cloud, carrying the energy out into the universe.

    To make molecular hydrogen, the atomic gas clouds needed to do some chemistry. It might be surprising to hear that any chemistry was going on at all, given that the entire universe had just three elements. The most sophisticated chemical models of early gas clouds, however, include nearly 500 possible reactions. Fortunately, to understand molecular hydrogen formation, we need concern ourselves with only two key processes.

    Chemists have named the first reaction associative detachment, a name fit for a psychiatric condition out of the DSM-V for which a clinician might prescribe some primordial lithium. Initially, most of the hydrogen in a gas cloud was in neutral atomic form, with the positive charge of a single proton cancelled out by the negative charge of a single orbiting electron. However, a small fraction of its atoms captured two electrons, creating a negatively charged hydrogen ion. These neutral hydrogen atoms and charged hydrogen ions “associated” with each other, causing the extra electron to detach and leaving behind neutral molecular hydrogen. In chemical notation, this can be represented as H + H- → H2 + e-. Associative detachment converted only about 0.01 percent of atomic hydrogen to molecules, but that small fraction allowed the clouds to begin to cool and become denser.

    When the cloud had become sufficiently cool and dense, a second chemical reaction began. It is called three-body association, and written as H + H + H → H2 + H. This ménage-à-trois begins with three separate hydrogen atoms, and ends with two of them coupled and the third one left out in the cold. Three-body association converted essentially all of the cloud’s remaining atomic hydrogen into molecular hydrogen. Once all of the hydrogen was fully molecular, the cloud cooled to the point where its gas could condense enough to form a star.

    5

    Stars

    From the formation of a dense cloud to the ignition of fusion at the heart of a star is a process whose complexity far exceeds what came before it. In fact, even the most sophisticated computer simulations available have yet to reach the point where the object becomes stellar in size, and fusion begins. Simulating most of the 200-million-year process is relatively easy, requiring only about 12 hours using high speed, parallel processing computer power. The problem lies in the final 10,000 years. As the density of the gas goes up, the structure of the cloud changes more and more rapidly. So, whereas for early times one needs only to calculate how the cloud changes every 100,000 years or so, for the final 10,000 years one must calculate the change every few days. This dramatic increase in the required number of calculation translates into more than a year of non-stop computer time on today’s fastest machines. Running simulations for the full range of possible starting conditions in these primordial clouds exceeds what can be achieved in a human lifetime. As a result, we still do not know the mass distribution for the first generation of stars. Since the mass of a star determines what elements it forges in its core, this hinders our ability to follow the pathway by which the universe began to synthesize the elements needed for life. Those of us who cannot wait to know the answer are counting on yet another hero: Moore’s Law.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 11:52 am on December 25, 2019 Permalink | Reply
    Tags: , , BASE Collaboration, , Dark Matter, , ,   

    From RIKEN: “Could the mysteries of antimatter and dark matter be linked?” 

    RIKEN bloc

    From RIKEN

    Nov. 15, 2019

    Contact

    Chief Scientist
    Stefan Ulmer
    Fundamental Symmetries Laboratory
    Chief Scientist Laboratories

    Jens Wilkinson
    RIKEN International Affairs Division
    Tel: +81-(0)48-462-1225 / Fax: +81-(0)48-463-3687
    Email: pr@riken.jp

    Could the mysteries of antimatter and dark matter be linked?

    Could the profound mysteries of antimatter and dark matter be linked? Thinking that they might be, scientists from the international BASE collaboration, led by Stefan Ulmer of the RIKEN Cluster for Pioneering Research, and collaborators have performed the first laboratory experiments to determine whether a slightly different way in which matter and antimatter interact with dark matter might be a key to solving both mysteries.

    BASE: Baryon Antibaryon Symmetry Experiment

    Dark matter and antimatter are both vexing problems for physicists trying to understand how our world works at a fundamental level.

    The problem with antimatter is that though the Big Bang should have created equal amounts of matter and antimatter, the world we live in is made only of matter. Antimatter is created every day in experiments and even by natural processes such as lightning, but it is quickly annihilated in collisions with regular matter. Predictions show that our understanding of the matter content of the Universe is off by nine orders of magnitude, and no one knows why the asymmetry exists.

    In the case of dark matter, it is known from astronomical observations that some unknown mass is influencing the orbits of stars in galaxies, but no one has been able to determine the exact microscopic properties of these particles. One theory is that they are a type of hypothetical particle known as an axion, which has an important role in explaining the lack of symmetry violation in the strong interaction in the standard model of particle physics.

    The BASE group collaborators wondered whether the lack of antimatter might be because it interacts differently with dark matter, and set out to test this. For the experiment, they used a specially designed device, called a Penning trap, to magnetically trap a single antiproton, preventing it from contacting ordinary matter and being annihilated. They then measured a property of the antiproton called its spin precession frequency. Normally, this should be constant in a given magnetic field, and a modulation of this frequency could be accounted for by an effect mediated by axion-like particles, which are hypothesized dark matter candidates.

    According to the first author of the study, Christian Smorra “For the first time, we have explicitly searched for an interaction between dark matter and antimatter, and though we did not find a difference, we set a new upper limit for the potential interaction between dark matter and antimatter.”

    Looking to the future, Stefan Ulmer of the RIKEN Cluster for Pioneering Research, who is spokesperson for the BASE Collaboration, says, “From now on, we plan to further improve the accuracy of our measurements of the spin precession frequency of the antiproton, allowing us set more and more stringent constraints on the fundamental invariance of charge, parity, and time, and to make the search for dark matter even more sensitive.”

    The work, published in Nature, was carried out by the RIKEN Fundamental Symmetries Laboratory and a working group at the PRISMA+ excellence cluster of the Johannes Gutenberg University Mainz (JGU), which has been active in the search for dark matter. It was conducted at the European Center for Nuclear Research (CERN), using the Antiproton Decelerator (AD). The research also involved scientists from the Max Planck Institute for Nuclear Physics in Heidelberg, CERN, the Johannes Gutenberg University Mainz (JGU), the Helmholtz Institute Mainz (HIM), the University of Tokyo, the GSI Darmstadt, the Leibniz University Hannover and the Physikalisch-Technische Bundesanstalt (PTB) Braunschweig. The research was performed as part of the work of the Max Planck-RIKEN-PTB Center for Time, Constants and Fundamental Symmetries, an international group established to develop high-precisions measurements to better understand the physics of our Universe.

    See the full article here .


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    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 8:52 am on December 6, 2019 Permalink | Reply
    Tags: , , , , Dark Matter,   

    From Ethan Siegel: “Why Humans Should Be Thankful That Our Universe Has Dark Matter” 

    From Ethan Siegel
    Dec 5, 2019

    1
    A galaxy that was governed by normal matter alone (L) would display much lower rotational speeds in the outskirts than towards the center, similar to how planets in the Solar System move. However, observations indicate that rotational speeds are largely independent of radius (R) from the galactic center, leading to the inference that a large amount of invisible, or dark, matter must be present. What isn’t greatly appreciated is that without dark matter, life as we know it would not exist. (WIKIMEDIA COMMONS USER INGO BERG/FORBES/E. SIEGEL)

    Without this one ingredient, there wouldn’t be enough ‘glue’ to hold the Universe together.

    Of all the things in the Universe to be thankful for — the stars, planets, atoms, molecules, and more that came together and made our existence possible — it seems odd that dark matter would be included.

    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.

    Even here in our own Solar System, dark matter might be present, but even its gravitational effects are totally negligible, contributing less than the dwarf planet Ceres does to all the orbits of the planets, moons, asteroids and Kuiper belt objects.

    And yet, without dark matter, the Universe as we know it wouldn’t exist the way it does. Stars would be extremely rare entities in the Universe, and large galaxies with Sun-like stars and Earth-like planets would be all but impossible. Dark matter enabled the Universe to give rise to us, and without it, we wouldn’t be here. Here’s the cosmic story that every one of us should be thankful for.

    2
    The X-ray (pink) and overall matter (blue) maps of various colliding galaxy clusters show a clear separation between normal matter and gravitational effects, some of the strongest evidence for dark matter. Although some of the simulations we perform indicate that a few clusters may be moving faster than expected, the simulations include gravitation alone, and other effects like feedback, star formation, and stellar cataclysms may also be important for the gas. Without dark matter, these observations (along with many others) cannot be sufficiently explained. (X-RAY: NASA/CXC/ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE, SWITZERLAND/D.HARVEY NASA/CXC/DURHAM UNIV/R.MASSEY; OPTICAL/LENSING MAP: NASA, ESA, D. HARVEY (ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE, SWITZERLAND) AND R. MASSEY (DURHAM UNIVERSITY, UK))

    On astronomical scales, particularly on large, cosmic ones, the observational evidence for dark matter is overwhelming. Without its gravitational effects:

    galaxies wouldn’t rotate as they’re observed to,
    individual galaxies would move too quickly to remain in bound clusters,
    colliding clusters of galaxies (above) wouldn’t show a separation between the normal (X-ray emitting) matter and the gravitational lensing (driven by dark matter) signals,
    the cosmic web wouldn’t show the clustering properties it exhibits,
    and the fluctuation pattern in the cosmic microwave background would look tremendously different.

    The suite of evidence supporting dark matter’s existence is overwhelming. But what isn’t generally appreciated is that if our Universe didn’t have dark matter, our galaxy couldn’t have held onto the raw ingredients that made life like humans and planets like Earth possible.

    3
    The final results from the Planck collaboration show an extraordinary agreement between the predictions of a dark energy/dark matter-rich cosmology (blue line) with the data (red points, black error bars) from the Planck team. All 7 acoustic peaks fit the data extraordinarily well, but about half of those peaks would not be present if there were no dark matter. (PLANCK 2018 RESULTS. VI. COSMOLOGICAL PARAMETERS; PLANCK COLLABORATION (2018))

    ESA/Planck 2009 to 2013

    Whatever dark matter is, it must have existed in roughly the same amount over the course of nearly the entire Universe. Observationally, the signatures of dark matter that show up in the cosmic microwave background [CMB]— which is required to explain the existence of about half of the “acoustic peak” features in the graph above — tell us that dark matter must have been present from when the Universe was a few thousand years old, at most.

    CMB per ESA/Planck

    Most models of making dark matter are only plausible in the first fraction-of-a-second after the Big Bang, even though it won’t become cosmologically important until later. But with the seeds of structure in place, arising from both normal matter and dark matter together, it’s only a matter of time and gravity until matter collapses into dense enough regions to form the first stars and proto-galaxies in the Universe.

    4
    The first stars and galaxies in the Universe will be surrounded by neutral atoms of (mostly) hydrogen gas, which absorbs the starlight and slows any ejecta. The large masses and high temperatures of these early stars helps ionize the Universe, but until enough heavy elements are formed and recycled into future generations of stars and planets, life and potentially habitable planets are utterly impossible. (NICOLE RAGER FULLER / NATIONAL SCIENCE FOUNDATION)

    Whether your Universe had dark matter or not wouldn’t matter all that much, from a high-level point of view, when it comes to the first stars. These stars will be form when large molecular clouds of (mostly hydrogen and helium) gas collapse, which takes tens to hundreds of millions of years in either case. The first stars, because of their utter lack of heavier elements, radiate and cool differently than modern stars; the average “first star” is about 25 times as massive as the average star formed today.

    These massive stars will be bright and short-lived, burning through their core’s fuel perhaps a thousand times faster than our Sun does. When the core runs out of fuel, these stars will contract, heat up, and burn through increasingly heavier elements. At some critical moment, the radiation pressure will drop as the fuel runs low, and the core will collapse under its own gravity, triggering a supernova explosion.

    5
    The anatomy of a very massive star throughout its life, culminating in a Type II Supernova when the core runs out of nuclear fuel. The final stage of fusion is typically silicon-burning, producing iron and iron-like elements in the core for only a brief while before a supernova ensues. Many of the supernova remnants will lead to the formation of neutron stars, which can produce the greatest abundances of the heaviest elements of all by colliding and merging. (NICOLE RAGER FULLER/NSF)

    These supernovae happen rapidly and in waves wherever the first stars were. But this is where dark matter’s presence is so important to our existence: these first supernovae are where a huge percentage of our heavy elements come from. The elements required for biology, including carbon, oxygen, nitrogen, phosphorous and sulphur, require these massive stars to live, die, and recycle their cosmic insides into the next generation of stars.

    In order to meaningfully contribute to forming rocky planets and organic compounds, those heavy elements need to not only be created (which they are in these stars and cataclysms, regardless of dark matter), but they need to be retained and put to good use. This is where, in these first, early star clusters, dark matter plays such a vital role.

    6
    An animation sequence of the 17th century supernova in the constellation of Cassiopeia. Surrounding material plus continued emission of EM radiation both play a role in the remnant’s continued illumination. A supernova is the typical fate for a star greater than about 10 solar masses, although there are some exceptions. The material in this supernova remnant moves extremely quickly, up to nearly 5% the speed of light. (NASA, ESA, AND THE HUBBLE HERITAGE STSCI/AURA)-ESA/HUBBLE COLLABORATION. ACKNOWLEDGEMENT: ROBERT A. FESEN (DARTMOUTH COLLEGE, USA) AND JAMES LONG (ESA/HUBBLE))

    We’ve observed supernova explosions in great detail, and one of the lessons we’ve learned is how quickly this material gets ejected from the stars that undergo their death throes in this manner. Typical speeds are substantial: on the order of 1,000 km/s, or a few tenths-of-a-percent of the speed of light. In fact, the Cassiopeia A supernova remnant, dating back to a 17th century explosion here in our Milky Way, has ejecta leaving it between 5,000 and 14,500 km/s!

    This new version of Chandra’s image of the Cassiopeia A supernova remnant has been specially processed to show with better clarity the appearance of Cas A in different bands of X-rays. This will aid astronomers in their efforts to reconstruct details of the supernova process such as the size of the star, its chemical makeup, and the explosion mechanism. The color scheme used in this image is the following: low-energy X-rays are red, medium-energy ones are green, and the highest-energy X-rays detected by Chandra are colored blue.

    For comparison, our own Sun orbits the Milky Way at a relatively paltry velocity of only 220 km/s, and if it were moving substantially faster (say, three times as fast), it would escape from our galaxy’s gravitational pull. The star clusters and early proto-galaxies in the young Universe are much less massive and much easier to gravitationally escape from. If we’re not careful, all the elements we worked so hard to create can get thrown out of these galaxies, knocking us back to square one in our Universe’s quest to form planets and life.

    7
    In theory, the majority of dark matter in any galaxy exists in a vast halo engulfing the normal matter, but occupying a much larger volume. While large galaxies, clusters of galaxies, and even larger structures can have their dark matter content determined indirectly, it’s challenging to trace out the dark matter distribution accurately. (ESO / L. CALÇADA)

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

    There’s other matter (like neutral gas) surrounding a supernova in the early Universe, but even the effect of smashing into all of that material is not enough to allow these young star clusters to hold onto most of their supernova ejecta. These low mass objects, tenuously bound together by their mutual gravity, will be unable to hold onto even modestly fast, energetic ejecta.

    But now, if you add dark matter, the story changes dramatically. Just as our galaxy has an enormous, diffuse halo of dark matter surrounding it, so should all large, gravitationally-driven structures of all sizes and scales in the Universe. Because of the enormous gravitational influence of this dark matter, and the fact that it continues to act on normal matter that attempts to escape out to much larger distance scales than the normal matter itself extends for, dark matter gives the Universe a chance to hold its structures together.

    8
    The Cigar Galaxy, M82, and its supergalactic winds (in red) that showcase the rapid new star formation occurring within it. This is the closest massive galaxy undergoing rapid star formation like this to us, and its winds are so powerful that nearly all of the heavy elements produced by the deaths of these stars would be permanently ejected without dark matter to keep it gravitationally bound. (NASA, ESA, THE HUBBLE HERITAGE TEAM, (STSCI / AURA); ACKNOWLEDGEMENT: M. MOUNTAIN (STSCI), P. PUXLEY (NSF), J. GALLAGHER (U. WISCONSIN))

    If it weren’t for the additional gravitation that a massive dark matter halo provides, the overwhelming amount of material ejected from a supernova would escape from galaxies forever. The same story would be true for neutron star mergers, white dwarf collisions, and other cataclysms that produce heavy elements in substantial quantities. Without these advanced building blocks remaining in what will become a galaxy, complex molecules and rocky planets would still remain impossible.

    When the next generation of stars attempted to form, it would have only paltry amounts of heavy elements if dark matter weren’t present. Whereas in our dark matter-rich Universe, these heavy elements build up substantially over time — they comprise about 1–2% of the total normal matter at present — in a dark matter-free Universe, the abundance of heavy elements would be negligible.

    9
    Both simulations (red) and galaxy surveys (blue/purple) display the same large-scale clustering patterns as one another, even when you look at the mathematical details. If dark matter weren’t present, a lot of this structure would not only differ in detail, but would be washed out of existence; galaxies would be rare and filled with almost exclusively light elements. (GERARD LEMSON AND THE VIRGO CONSORTIUM)

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Furthermore, the standard scenario of a large-scale cosmic web growing and funneling matter into it wouldn’t work the same way either, as a Universe without dark matter doesn’t have that same material to drive the formation of structure. With normal matter alone, smaller-scale structures would be washed out, and the bigger galaxies that formed would be extremely sparse and few in number throughout the cosmos.

    Even in these astronomical rarities, the occasional large galaxy would still be unable to hold onto its heavier elements, even in the most central regions in the most massive galaxies. Even if a small amount of these elements were retained, these environments are presently thought to be uninhabitable due to large amounts of cosmic radiation and nearby cataclysms.

    10
    This multiwavelength view of the Milky Way’s galactic center goes from the X-ray through the optical and into the infrared, showcasing Sagittarius A* and the intragalactic medium located some 25,000 light years away. The black hole has a mass of approximately 4 million Sun, while the Milky Way as a whole forms less than one new Sun’s worth of stars every year. Without dark matter, even the galactic center would be largely devoid of heavy elements, making the prospect of life forming anywhere in the Universe a near impossibility. (X-RAY: NASA/CXC/UMASS/D. WANG ET AL.; OPTICAL: NASA/ESA/STSCI/D.WANG ET AL.; IR: NASA/JPL-CALTECH/SSC/S.STOLOVY)

    NASA/Chandra X-ray Telescope

    NASA/ESA Hubble Telescope

    NASA/Spitzer Infrared Telescope

    In a Universe without dark matter, we might still have stars and galaxies, but the only planets would be gas giant worlds, with no rocky ones to speak of. Without carbon, there are no organic molecules; without oxygen, there is no liquid water; without a whole slew of elements from the periodic table, biochemical life would be completely impossible.

    Only with the presence of massive dark matter halos, surrounding galaxies and driving the growth of the cosmic web, can a planet like Earth or carbon-based life like we find terrestrially be formed. As we’ve come to understand what makes up our Universe and how it grew to be this way, one inescapable conclusion emerges: dark matter is fundamentally necessary for life to arise. Without it, the chemistry that underlies all life could never have occurred. Today and every day, we should be thankful for every part of the cosmic story that allowed us to exist. Even dark matter.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 9:14 am on December 2, 2019 Permalink | Reply
    Tags: "The Universe's Baby Picture Could Help Us Predict Its Future", , , , , , , , Dark Matter   

    From Curiosity: “The Universe’s Baby Picture Could Help Us Predict Its Future” 

    Curiosity Makes You Smarter

    From From Curiosity

    September 18, 2018 [Just now in social media]
    Elizabeth Howell

    Look up at the sky and you see stars and galaxies and planets. But way in the background lurks an interesting form of radiation known as the Cosmic Microwave Background [CMB]. That’s the universe’s baby picture, and when we study that picture, we don’t only see its past — we also see its future.

    CMB per ESA/Planck

    ESA/Planck 2009 to 2013

    What’s Behind the Baby Face?

    Next time you pull out your baby pictures, take a look at the details: what you looked like, who you were with, what you were doing. Often, we can “see” a bit of ourselves today by looking at what we used to be long ago. Our parents, friends, and activities all shaped us into the person we became.

    This concept not only works for people, but it’s also a useful analogy for science. Even our 13.8-billion-year-old universe was a baby in a time long, long ago – just after the universe was formed in an event known as the Big Bang. Shortly after birth, the universe was so hot and so dense that not even light could penetrate the tiny cocoon. Then space expanded rapidly, allowing light to shine through and molecules to come together.

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

    The first stars and galaxies turned on, and just after them came the first planets.

    Funny enough, we can still see evidence of all that activity by using microwaves. Light is in a spectrum; we can see some of it with our eyes, but there are other forms of light, like X-rays and microwaves, that we can’t see except with telescopes or other scientific instruments. Microwaves have extremely long wavelengths, and by using them, we can peer all the way back to the universe’s first few thousand years. Scientists call this “baby picture” the Cosmic Microwave Background, or CMB.

    1
    NASA WMAP

    NASA/WMAP 2001 to 2010

    Later this month, NASA will send a balloon with a science experiment — known as the Primordial Inflation Polarization Explorer (PIPER) — to the edge of our atmosphere.

    3

    There, PIPER will take more baby pictures of the universe. But why do we care in the first place? What’s the use of looking at the radiation of the universe from so long ago, at a time long before the Earth formed? What’s the point?

    Well, for one thing, it will help us understand the universe’s ultimate fate. Maybe we’re going to keep expanding forever, or maybe we’re going to collapse into a huge crunch. We can best understand this by mapping what the universe is made of. A past mission called the Wilkinson Microwave Anisotropy Probe (WMAP) helped scientists come up with some estimates.

    It turns out that 5 percent of the matter in the universe is normal matter, the kind that telescopes can see. The rest (95 percent) is made up of dark energy and dark matter that telescopes can’t sense except through their effects on normal matter, such as the way they bend light.

    Dark energy and dark matter are exotic and we know little about them, but they’re still super important. They make up most of the mass of the universe. They alter the paths of light and of other objects. And by studying dark matter and dark energy, we can understand how fast the universe is expanding and whether the universe will expand forever, which most scientists think is likely.

    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 Research

    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.

    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

    There’s a lot more you can see peering at the CMB, and NASA has a whole Tumblr page explaining more about our universe’s history and what the PIPER mission will accomplish. So next time you look up at the sky, remember — our universe had a pretty baby face, and we’re only just getting a clear picture of it.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Curiosity Makes You Smarter

    Curiosity is on a mission to make learning easier and more fun than it has ever been. Our goal is to ignite curiosity and inspire people to learn. Each day, we create and curate engaging topics for millions of lifelong learners worldwide.

    Experience Curiosity on our website, through our apps and across social media. We designed Curiosity with your busy life in mind. Our editors find interesting and important topics that you’ll want to know more about, and introduce you to the best ways to keep learning.

    We hope you make Curiosity part of your daily digital diet. Never stop learning!

     
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