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

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

    ESA Space For Europe Banner

    From European Space Agency – United space in Europe

    From United space in Europe

    16/01/2020

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

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

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

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

    1

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

    ESA/XMM Newton

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

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

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

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

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

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

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

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

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

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

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

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

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

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

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

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

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

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

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

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

    4
    The cosmic budget of ‘ordinary’ matter

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

    ______________________________________________________________________

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

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

    Coma cluster via NASA/ESA Hubble

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


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


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

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

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

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

    Dark Matter Research

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

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

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

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

    Dark Matter Particle Explorer China

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

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


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

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

    ______________________________________________________________________

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

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

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

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

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

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

    ESA/Planck 2009 to 2013

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

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

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

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

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

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

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

    See the full article here .


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

    Stem Education Coalition

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

    ESA50 Logo large

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

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


    From The New York Times

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

    1
    Brian Stauffer

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

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

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

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

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

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

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

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

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

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

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

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

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

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

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

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

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

    Hubble trouble

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

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

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

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

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

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

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

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

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

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

    CMB per ESA/Planck


    ESA/Planck 2009 to 2013

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

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

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

    ‘Cosmological Whac-a-Mole’

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

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

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

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

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

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

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

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

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

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

    Doomsday? Nah, nevermind

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

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

    Inflation

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

    HPHS Owls

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

    Alan Guth’s notes:

    Alan Guth’s original notes on inflation

    Nobody knows what drove inflation.

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

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

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

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

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

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

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

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

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

    The phantom cosmos

    But the future is still up for grabs.

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

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

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

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

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

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

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

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

    ESA/Euclid spacecraft depiction

    NASA/WFIRST

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

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

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

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

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

    From SLAC National Accelerator Lab

    January 13, 2020
    Manuel Gnida

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

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

    NASA/Fermi LAT

    NASA/Fermi Gamma Ray Space Telescope

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

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

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

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

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

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

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

    Two sensitive ‘eyes’ on the sky

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

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

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

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

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

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

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

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

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

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

    Potential hint at dark matter.

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

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

    Coma cluster via NASA/ESA Hubble

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


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


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

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

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

    Dark Matter Research

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

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

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

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

    Dark Matter Particle Explorer China

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

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


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

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

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

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

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

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

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

    Planning next steps

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

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

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

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

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

    ESA/Euclid spacecraft depiction

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

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

    See the full article here .


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    Please help promote STEM in your local schools.

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    SLAC/LCLS


    SLAC/LCLS II projected view


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

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

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

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    January 13, 2020
    Catherine N. Steffel

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

    But this wasn’t always the case.

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

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

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

    Constraining cosmology with CMB polarization

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

    CMB per ESA/Planck

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

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

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

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

    Destination: Antarctica

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

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

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

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

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

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

    Gravitational Lensing NASA/ESA

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

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

    Destination: Chile

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

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

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

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

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

    Destination: Unspoiled places

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

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

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

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

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

    See the full here.


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    FNAL Icon

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

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

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

    Wired logo

    From WIRED

    December 17, 2019
    Natalie Wolchover

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

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

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

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

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

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

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

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

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

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

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

    A Moving Shot

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

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

    3
    Illustration: Dillon Brout

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

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

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

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

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

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

    Not All the Same

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

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

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

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

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

    See the full article here .

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    Please help promote STEM in your local schools.

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  • richardmitnick 3:29 pm on December 11, 2019 Permalink | Reply
    Tags: "The Big Questions: Josh Frieman on Dark Energy", , , , , D, , Dark Energy, , Energy.cov, energy.gov, O,   

    From Energy.gov: “The Big Questions: Josh Frieman on Dark Energy” 

    DOE Main

    From Energy.gov

    1

    Distinguished Scientists Fellow Josh Frieman from Fermilab led the Dark Energy Survey at the Cerro Tololo Inter-American Observatory in Chile.
    Image courtesy of Fermilab, Reidar Hahn

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

    The Big Questions series features perspectives from the five recipients of the Department of Energy Office of Science’s 2019 Distinguished Scientists Fellows Award describing their research and what they plan to do with the award.

    Contributing Author Credit: Josh Frieman is the division head of particle physics at Fermilab.

    Why is the expansion of the universe speeding up?

    This question has been at the center of my research for the last 20 years. But let’s start at the beginning — the beginning of the universe.

    The universe began in a Big Bang about 14 billion years ago. To get a sense of how old the universe is, if you crammed the 14 billion years of cosmic history into a single year, a person’s lifespan would only be about 0.2 seconds long.

    When I was in college, I attended a lecture on cosmology, in which the speaker moved from the current time all the way back to the Big Bang, discussing how we could understand the earliest moments of the universe. I was hooked. I realized that’s what I wanted to be when I grew up: a cosmologist. I realized that cosmology is like archeology on a grand scale. Rather than using pottery shards to reconstruct ancient civilizations, you could use astronomical observations to reconstruct the beginning of time itself.

    It was the early 1980s, and cosmology was undergoing a renaissance. Combining discoveries from particle physics and cosmology provided insights into both fields and enabled us to use the very early universe as a physics laboratory. I had, like Forrest Gump, wandered into the right historical place at the right historical time completely by accident.

    After graduate school at the University of Chicago and a postdoc at the Department of Energy’s (DOE) Stanford Linear Accelerator Center (SLAC), I moved to the DOE’s Fermi National Accelerator Laboratory.


    Like most cosmologists back then, I focused on theoretical explanations of the universe’s history. At the time, we simply didn’t have the tools to make the observations we needed to test our theories. We were frustratingly data starved.

    But since then, observational cosmology has undergone an explosion. Projects supported by DOE and others are collecting ever more information about the current and historical universe. In the 2000s, I had the privilege of leading the Sloan Digital Sky Survey (SDSS) Supernova Survey, which discovered more than 500 type Ia supernovae to study cosmic expansion. More recently, I directed the Dark Energy Survey, which used a 570-megapixel camera to take photos of one-eighth of the sky. This project brought together an international collaboration of more than 400 scientists. This team collected information on more than 300 million galaxies.

    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 DOE Office of Science’s High Energy Physics program has really been at the vanguard of these and other cosmic surveys. DOE’s willingness to follow its scientists into new modes of discovery is a tremendous strength of the system.

    As a result of these projects, we are now swimming in a sea of cosmological big data. This tidal wave is allowing us to put our theories to the test.

    One of the biggest open questions in cosmology today is about the expansion of the universe. Back in the 1920s, Edwin Hubble had discovered that the universe is expanding: other galaxies are moving away from the Milky Way (and from each other). Since

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

    We don’t know what’s causing galaxies to speed away from us faster and faster; we don’t think it’s personal. Instead, we have a good hunch that it’s something we call dark energy. From measurements we’ve made with the Dark Energy Survey and other experiments, we estimate that dark energy makes up about 70 percent of the universe.

    Right now, our team is using data the Dark Energy Survey collected to address this puzzle. Although we’ve already written 250 papers, we’ve analyzed only a small portion of our data so far, and there’s more work to do to pull out dark energy’s subtle effects. I plan to use this award to support students and post-docs at Fermilab and the University of Chicago to continue this analysis and to help lay the groundwork for future studies.

    It’s a privilege to be part of this collective endeavor to understand the cosmos. The national laboratories are delivering remarkable insights into the universe. I am humbled to be in this company and look forward to the many discoveries yet to come.

    The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit https://www.energy.gov/science.

    See the full article here .

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    The mission of the Energy Department is to ensure America’s security and prosperity by addressing its energy, environmental and nuclear challenges through transformative science and technology solutions.

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

    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 .

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    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!

     
  • richardmitnick 12:11 pm on October 31, 2019 Permalink | Reply
    Tags: "By the Numbers: Dark matter", , , , , Dark Energy,   

    From Penn Today: “By the Numbers: Dark matter” 


    From Penn Today

    October 30, 2019
    Erica K. Brockmeier

    Key facts and figures about the unseen matter that remains one of cosmology’s greatest unsolved mysteries.

    1
    This image taken by the Hubble Space Telescope depicts a massive ring of dark matter surrounding the center of the CL0024+17 galaxy cluster. The computationally-modeled and superimposed dark matter ring spans about five million light years and is hypothesized to exist based on observed distortions of the distant galaxies. (Image: NASA, ESA, M. J. Jee and H. Ford et al., Johns Hopkins University)

    With a number of celebrations focused on the ethereal happening this time of year, from Día de los Muertos to Halloween, Oct. 31st is also a day for celebrating one of the most mysterious phenomena of the universe: Dark matter.

    Scientists and astronomy enthusiasts around the world will celebrate Dark Matter Day by reflecting on the ongoing efforts of the observational astronomers and theoretical physicists who are working to understand the unseen forces that shape the structure and nature of the universe.

    Penn Today delves into key facts and figures on what dark matter is, ongoing research that seeks to gain a better understanding this unseen force, and Penn’s role in this cutting-edge field of study.

    85%

    The amount of matter in the universe thought to be made of dark matter. Scientists refer to this type of matter as “dark” because it doesn’t interact with light or other parts of the electromagnetic spectrum, so it can’t be detected with telescopes.

    Scientists first knew about dark matter because of observations of spiral galaxies, which found that stars that were farther away from the center of the galaxy travelled faster than expected. Since galaxies weren’t flying apart, astronomers invoked dark matter as an additional source of gravity that was holding stars on their regular orbits.

    In Kepler’s laws of planetary motion, the velocity of an object in orbit decreases the farther away it is from the center, a phenomenon seen in the solar system, with Jupiter and Saturn taking longer to travel around the sun that Earth or Mars. But this wasn’t the case for spiral galaxies: The velocity barely decreased, even farther out from the center where there were hardly any stars. This led researchers to speculate that dark matter actually dominated the gravity at large distances.

    _____________________________________________________________
    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.


    _____________________________________________________________

    Other astronomical observations, like how galaxies clustered together when the universe was forming, imprints on the cosmic microwave background [below], and the amount of gravitational lensing, or how much light “bends” between massive objects at long distances, also lend support for the existence of dark matter.

    Gravitational Lensing NASA/ESA

    46

    The number of ongoing experiments that are on the hunt for dark matter.

    Dark matter experiments use a wide range of devices and methods, including underground detectors like DEAP and the LZ experiment, space-based telescopes like the Dark Matter Particle Explorer, high-altitude Antarctic balloons as part of the general antiparticle spectrometer experiment, and high-energy particle colliders like the Large Hadron Collider.

    LZ xenon detector in the Surface Assembly Lab cleanroom at SURF

    3
    GAPS (General Antiparticle Spectrometer) http://stratocat.com.ar/fichas-e/2012/TAK-20120603.htm

    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

    28,999

    Number of papers on the arXiv that mention “dark matter,” which represents 1.8% of the entire arXiv database. The arXiv is a preprint server for research papers from the natural sciences, computer science, statistics, engineering, and economics, where 1.6 million articles have been posted since 1992.

    The 2019 Nobel Prize in Physics was awarded to James Peebles for his theoretical work in physical cosmology, and Peebles’ research during the 1980’s provided support for the existence of dark matter. He was also one of the first researchers to publish the theory of cold dark matter, which hypothesizes that dark matter moves slowly when compared to the speed of light.

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

    14 billion

    The age of the universe in the Big Bang cosmological model.

    4

    7.5 billion

    Number of years ago when objects in the universe began flying apart from one another at a faster rate. This shift towards accelerated expansion, discovered in the late 1990s, led scientists to hypothesize that an unseen form of energy could explain this phenomenon: dark energy.

    _____________________________________________________________
    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

    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.
    _____________________________________________________________

    To help explain how this acceleration continues to pull galaxies apart, countering the opposing force of gravity, scientists are also working on theories and running experiments to understand the nature of this second mysterious cosmological entity. So far, the source of most of the matter and energy in the universe remains largely unknown.

    5

    The number of episodes of “Star Trek” that feature dark matter, one example being the “In Theory” episode of “Star Trek: The Next Generation,” where the Enterprise finds a nebula made of dark matter that causes distortions in space.

    This episode originally aired in 1991, a time when dark matter theories were starting to become well-established in the scientific community and as major observational experiments, like the Cosmic Background Explorer, started to provide supporting evidence for the existence of dark matter.

    5
    The COBE satellite

    COBE/CMB

    NASA/WMAP 2001 to 2010

    Cosmic Microwave Background NASA/WMAP

    ESA/Planck 2009 to 2013

    CMB per ESA/Planck

    30+

    Number of Penn students, post-docs, and faculty involved with dark matter and dark energy research, including researchers in the labs of Gary Bernstein, Mark Devlin, Josh Klein, Bhuvnesh Jain, Elliot Lipeles, Christopher Mauger, Masao Sako, and Mark Trodden.

    Recent work from Penn about dark matter and dark energy includes a new hypotheses on the phase of dark matter, evidence for the boundary of dark matter “halos,” and developing the largest contiguous maps showing the concentration of dark matter in the cosmos.

    Researchers at Penn are also analyzing the 50 terabytes of data collected during the Dark Energy Survey [above], the largest galaxy survey to date, which completed six years of observations in January. Penn scientists will use this data to see if their theories about dark matter and dark energy align with the data collected during the survey. They hope to shed light on recent uncovered puzzles on the expansion of the universe and the distribution of matter.

    See the full article here .

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    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 9:49 am on October 20, 2019 Permalink | Reply
    Tags: A lot in common with facial recognition at Facebook and other social media., , , , , Dark Energy, , , Improving on standard methods for estimating the dark matter content of the universe through artificial intelligence., , The scientists used their fully trained neural network to analyse actual dark matter maps from the KiDS-​450 dataset., Using cutting-​edge machine learning algorithms for cosmological data analysis.,   

    From ETH Zürich: “Artificial intelligence probes dark matter in the universe” 

    ETH Zurich bloc

    From ETH Zürich

    18.09.2019
    Oliver Morsch

    A team of physicists and computer scientists at ETH Zürich has developed a new approach to the problem of dark matter and dark energy in the universe. Using machine learning tools, they programmed computers to teach themselves how to extract the relevant information from maps of the universe.

    1
    Excerpt from a typical computer-​generated dark matter map used by the researchers to train the neural network. (Source: ETH Zürich)

    Understanding the how our universe came to be what it is today and what will be its final destiny is one of the biggest challenges in science. The awe-​inspiring display of countless stars on a clear night gives us some idea of the magnitude of the problem, and yet that is only part of the story. The deeper riddle lies in what we cannot see, at least not directly: dark matter and dark energy. With dark matter pulling the universe together and dark energy causing it to expand faster, cosmologists need to know exactly how much of those two is out there in order to refine their models.

    At ETH Zürich, scientists from the Department of Physics and the Department of Computer Science have now joined forces to improve on standard methods for estimating the dark matter content of the universe through artificial intelligence. They used cutting-​edge machine learning algorithms for cosmological data analysis that have a lot in common with those used for facial recognition by Facebook and other social media. Their results have recently been published in the scientific journal Physical Review D.

    Facial recognition for cosmology

    While there are no faces to be recognized in pictures taken of the night sky, cosmologists still look for something rather similar, as Tomasz Kacprzak, a researcher in the group of Alexandre Refregier at the Institute of Particle Physics and Astrophysics, explains: “Facebook uses its algorithms to find eyes, mouths or ears in images; we use ours to look for the tell-​tale signs of dark matter and dark energy.” As dark matter cannot be seen directly in telescope images, physicists rely on the fact that all matter – including the dark variety – slightly bends the path of light rays arriving at the Earth from distant galaxies. This effect, known as “weak gravitational lensing”, distorts the images of those galaxies very subtly, much like far-​away objects appear blurred on a hot day as light passes through layers of air at different temperatures.

    Weak gravitational lensing NASA/ESA Hubble

    Cosmologists can use that distortion to work backwards and create mass maps of the sky showing where dark matter is located. Next, they compare those dark matter maps to theoretical predictions in order to find which cosmological model most closely matches the data. Traditionally, this is done using human-​designed statistics such as so-​called correlation functions that describe how different parts of the maps are related to each other. Such statistics, however, are limited as to how well they can find complex patterns in the matter maps.

    Neural networks teach themselves

    “In our recent work, we have used a completely new methodology”, says Alexandre Refregier. “Instead of inventing the appropriate statistical analysis ourselves, we let computers do the job.” This is where Aurelien Lucchi and his colleagues from the Data Analytics Lab at the Department of Computer Science come in. Together with Janis Fluri, a PhD student in Refregier’s group and lead author of the study, they used machine learning algorithms called deep artificial neural networks and taught them to extract the largest possible amount of information from the dark matter maps.

    2
    Once the neural network has been trained, it can be used to extract cosmological parameters from actual images of the night sky. (Visualisations: ETH Zürich)

    In a first step, the scientists trained the neural networks by feeding them computer-​generated data that simulates the universe. That way, they knew what the correct answer for a given cosmological parameter – for instance, the ratio between the total amount of dark matter and dark energy – should be for each simulated dark matter map. By repeatedly analysing the dark matter maps, the neural network taught itself to look for the right kind of features in them and to extract more and more of the desired information. In the Facebook analogy, it got better at distinguishing random oval shapes from eyes or mouths.

    More accurate than human-​made analysis

    The results of that training were encouraging: the neural networks came up with values that were 30% more accurate than those obtained by traditional methods based on human-​made statistical analysis. For cosmologists, that is a huge improvement as reaching the same accuracy by increasing the number of telescope images would require twice as much observation time – which is expensive.

    Finally, the scientists used their fully trained neural network to analyse actual dark matter maps from the KiDS-​450 dataset. “This is the first time such machine learning tools have been used in this context,” says Fluri, “and we found that the deep artificial neural network enables us to extract more information from the data than previous approaches. We believe that this usage of machine learning in cosmology will have many future applications.”

    As a next step, he and his colleagues are planning to apply their method to bigger image sets such as the Dark Energy Survey.

    Also, more cosmological parameters and refinements such as details about the nature of dark energy will be fed to the neural networks.

    See the full article here .

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    Please help promote STEM in your local schools.

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    ETH Zurich campus
    ETH Zürich is one of the leading international universities for technology and the natural sciences. It is well known for its excellent education, ground-breaking fundamental research and for implementing its results directly into practice.

    Founded in 1855, ETH Zürich today has more than 18,500 students from over 110 countries, including 4,000 doctoral students. To researchers, it offers an inspiring working environment, to students, a comprehensive education.

    Twenty-one Nobel Laureates have studied, taught or conducted research at ETH Zürich, underlining the excellent reputation of the university.

     
  • richardmitnick 1:46 pm on September 13, 2019 Permalink | Reply
    Tags: , , , , Dark Energy, ,   

    From NASA JPL-Caltech: “NASA’s WFIRST Will Help Uncover the Universe’s Fate” 

    NASA JPL Banner

    From NASA JPL-Caltech

    September 13, 2019

    Calla Cofield
    Jet Propulsion Laboratory, Pasadena, Calif.
    626-808-2469
    calla.e.cofield@jpl.nasa.gov

    Written by Ashley Balzer
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    1
    NASA WFIRST depiction. Credit: NASA’s Goddard Space Flight Center

    Scientists have discovered that a mysterious pressure dubbed “dark energy” makes up about 68% of the total energy content of the cosmos, but so far we don’t know much more about it.

    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.

    Exploring the nature of dark energy is one of the primary reasons NASA is building the Wide Field Infrared Survey Telescope (WFIRST), a space telescope whose measurements will help illuminate the dark energy puzzle. With a better understanding of dark energy, we will have a better sense of the past and future evolution of the universe.

    An Expanding Cosmos

    Until the 20th century, most people believed that the universe was static, remaining essentially unchanged throughout eternity. When Einstein developed his general theory of relativity in 1915, describing how gravity acts across the fabric of space-time, he was puzzled to find that the theory indicated the cosmos must either expand or contract. He made changes to preserve a static universe, adding something he called the “cosmological constant,” even though there was no evidence it actually existed. This mysterious force was supposed to counteract gravity to hold everything in place.

    However, as the 1920s were coming to a close, astronomer Georges Lemaitre, and then Edwin Hubble, made the startling discovery that with very few exceptions, galaxies are racing away from each other.

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

    The universe was far from static – it was ballooning outward. Consequently, if we imagine rewinding this expansion, there must have been a time when everything in the universe was almost impossibly hot and close together.

    The End of the Universe: Fire or Ice?

    The Big Bang theory describes the expansion and evolution of the universe from this initial superhot, superdense state. Scientists theorized that gravity would eventually slow and possibly even completely reverse this expansion. If the universe had enough matter in it, gravity would overcome the expansion, and the universe would collapse in a fiery “Big Crunch.”

    If not, the expansion would never end – galaxies would grow farther and farther away until they pass the edge of the observable universe. Our distant descendants might have no knowledge of the existence of other galaxies since they would be too far away to be visible. Much of modern astronomy might one day be reduced to mere legend as the universe gradually fades to an icy black.

    The Universe Isn’t Just Expanding – It’s Accelerating

    Astronomers have measured the rate of expansion by using ground-based telescopes to study relatively nearby supernova explosions. The mystery escalated in 1998 when Hubble Space Telescope observations of more distant supernovae helped show that the universe actually expanded more slowly in the past than it does today.(?) The expansion of the universe is not slowing down due to gravity, as everyone thought. It’s speeding up.

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

    Fast forward to today. While we still don’t know what exactly is causing the acceleration, it has been given a name – dark energy. This mysterious pressure remained undiscovered for so long because it is so weak that gravity overpowers it on the scale of humans, planets and even the galaxy. It is present in the room with you as you read, within your very body, but gravity counteracts it so you don’t go flying out of your seat. It is only on an intergalactic scale that dark energy becomes noticeable, acting like a sort of weak opposition to gravity.

    What Is Dark Energy?

    What exactly is dark energy? More is unknown than known, but theorists are chasing down a couple of possible explanations. Cosmic acceleration could be caused by a new energy component, which would require some adjustments to Einstein’s theory of gravity – perhaps the cosmological constant, which Einstein called his biggest blunder, is real after all.

    Alternatively, Einstein’s theory of gravity may break down on cosmological scales. If this is the case, the theory will need to be replaced with a new one that incorporates the cosmic acceleration we have observed. Theorists still don’t know what the correct explanation is, but WFIRST will help us find out.

    WFIRST Will Illuminate Dark Energy

    Previous missions have gathered some clues, but so far they haven’t yielded results that strongly favor one explanation over another. With the same resolution as Hubble’s cameras but a field of view that is 100 times larger, WFIRST will generate never-before-seen big pictures of the universe. The new mission will advance the exploration of the dark energy mystery in ways that other telescopes can’t by mapping how matter is structured and distributed throughout the cosmos, and also by measuring large numbers of distant supernovae. The results will indicate how dark energy acts across the universe, and whether and how it has changed over cosmic history.

    The mission will use three survey methods to search for an explanation of dark energy. The High Latitude Spectroscopic Survey will measure accurate distances and positions of millions of galaxies using a “standard ruler” technique. Measuring how the distribution of galaxies varies with distance will give us a window into the evolution of dark energy over time. This study will connect the galaxies’ distances with the echoes of sound waves just after the Big Bang and will test Einstein’s theory of gravity over the age of the universe.

    The High Latitude Imaging Survey will measure the shapes and distances of multitudes of galaxies and galaxy clusters. The immense gravity of massive objects warps space-time and causes more distant galaxies to appear distorted. Observing the degree of distortion allows scientists to infer the distribution of mass throughout the cosmos. This includes all of the matter we can see directly, like planets and stars, as well as dark matter – another dark cosmic mystery which is visible only through its gravitational effects on normal matter. This survey will provide an independent measurement of the growth of large-scale structure in the universe and how dark energy has affected the cosmos.

    WFIRST will also conduct a survey of one type of exploding star, building on the observations that led to the discovery of accelerated expansion. Type Ia supernovae occur when a white dwarf star explodes. Type Ia supernovae generally have the same absolute brightness at their peak, making them so-called “standard candles.” That means astronomers can determine how far away they are by seeing how bright they look from Earth – and the farther they are, the dimmer they appear. Astronomers will also look at the particular wavelengths of light coming from the supernovae to find out how fast the dying stars are moving away from us. By combining distances with brightness measurements, scientists will see how dark energy has evolved over time, providing a cross-check with the two high-latitude surveys.

    “The WFIRST mission is unique in combining these three methods. It will lead to a very robust and rich interpretation of the effects of dark energy and will allow us to make a definite statement about the nature of dark energy,” said Olivier Doré, a research scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and leader of the team planning the first two survey methods with WFIRST.

    Discovering how dark energy has affected the universe’s expansion in the past will shed some light on how it will influence the expansion in the future. If it continues to accelerate the universe’s expansion, we may be destined to experience a “Big Rip.” In this scenario, dark energy would eventually become dominant over the fundamental forces, causing everything that is currently bound together – galaxies, planets, people – to break apart. Exploring dark energy will allow us to investigate, and possibly even foresee, the universe’s fate.

    For more information about WFIRST, visit:

    http://www.nasa.gov/wfirst.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    NASA JPL Campus

    Jet Propulsion Laboratory (JPL)) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge, on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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