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  • richardmitnick 12:56 pm on February 4, 2023 Permalink | Reply
    Tags: "3 new studies indicate a conflict at the heart of cosmology", "The Big Think", , , , , , Dark Matter,   

    From “The Big Think” : “3 new studies indicate a conflict at the heart of cosmology” 

    From “The Big Think”

    2.1.23
    Don Lincoln

    The Universe isn’t as “clumpy” as we think it should be.

    1
    Credit: NASA.

    Key Takeaways

    Telescopes are essentially time machines. As we examine galaxies that are at greater and greater distances from the Earth, we are looking further and further back in time. A new series of studies that examine the “clumpiness” of the Universe indicates that there might be a conflict at the heart of cosmology. The Big Bang theory is still sound, but it may need to be tweaked.

    A series of three scientific papers describing the expansion history of the Universe is telling a confusing tale, with predictions and measurements slightly disagreeing.

    While this disagreement isn’t considered a fatal disproof of modern cosmology, it could be a hint that our theories need to be revised.

    PRD “Joint analysis of DES Year 3 data and CMB lensing from SPT and Planck I: Construction of CMB Lensing Maps and Modeling Choices”
    PRD “Joint analysis of DES Year 3 data and CMB lensing from SPT and Planck II: Cross-correlation measurements and cosmological constraints”
    PRD “Joint analysis of DES Year 3 data and CMB lensing from SPT and Planck III: Combined cosmological constraints”

    Creation stories, both ancient and modern

    Understanding exactly how the world around us came into existence is a question that has bothered humanity for millennia. All around the world, people have devised stories — from the ancient Greek legend of the creation of the Earth and other primordial entities from Chaos (as first written down by Hesiod) to the Hopi creation myth (which describes a series of different kinds of creatures being created, eventually ending up as humans).

    In modern times, there are still competing creation stories, but there is one that is grounded in empiricism and the scientific method: the idea that about 13.8 billion years ago, the Universe began in a much smaller and hotter compressed state, and it has been expanding ever since then. This idea is colloquially called the “Big Bang,” although different writers use the term to mean slightly different things. Some use it to refer to the exact moment at which the Universe came into existence and began to expand, while others use it to refer to all moments after the beginning. For those writers, the Big Bang is still ongoing, as the expansion of the Universe continues.

    The beauty of this scientific explanation is that it can be tested. Astronomers rely on the fact that light has a finite speed, which means that it takes time for light to cross the cosmos. For example, the light we see as the Sun shining was emitted eight minutes before we see it. Light from the nearest star took about four years to get to Earth, and light from elsewhere in the cosmos can take billions of years to arrive.

    The telescope as a time machine

    Effectively, this means that telescopes are time machines. By looking at more and more distant galaxies, astronomers are able to see what the Universe looked like in the distant past. By stitching together observations of galaxies at different distances from the Earth, astronomers can unravel the evolution of the cosmos.

    The recent measurements use two different telescopes to study the structure of the Universe at different cosmic epochs. One facility, called the South Pole Telescope (SPT), looks at the earliest possible light, emitted a mere 380,000 years after the Universe began.

    At that time, the Universe was 0.003% its current age. If we consider the current cosmos to be equivalent to a 50-year-old person, the SPT looks at the Universe when it was a mere 12 hours old.

    The second facility is called the Dark Energy Survey (DES).
    ___________________________________________________________________
    The Dark Energy Survey

    Dark Energy Camera [DECam] built at The DOE’s Fermi National Accelerator Laboratory.

    NOIRLab National Optical Astronomy Observatory Cerro Tololo Inter-American Observatory (CL) Victor M Blanco 4m Telescope which houses the Dark-Energy-Camera – DECam at Cerro Tololo, Chile at an altitude of 7200 feet.

    NOIRLabNSF NOIRLab NOAO Cerro Tololo Inter-American Observatory(CL) approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.

    The Dark Energy Survey 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. The Dark Energy Survey began searching the Southern skies on August 31, 2013.

    According to Albert 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.

    Nobel Prize in Physics for 2011 Expansion of the Universe

    4 October 2011

    The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2011

    with one half to

    Saul Perlmutter
    The Supernova Cosmology Project
    The DOE’s Lawrence Berkeley National Laboratory and The University of California-Berkeley,

    and the other half jointly to

    Brian P. Schmidt
    The High-z Supernova Search Team,
    The Australian National University, Weston Creek, Australia.

    and

    Adam G. Riess
    The High-z Supernova Search Team,The Johns Hopkins University and
    The Space Telescope Science Institute, Baltimore, MD.
    Written in the stars

    “Some say the world will end in fire, some say in ice…” *

    What will be the final destiny of the Universe? Probably it will end in ice, if we are to believe this year’s Nobel Laureates in Physics. They have studied several dozen exploding stars, called supernovae, and discovered that the Universe is expanding at an ever-accelerating rate. The discovery came as a complete surprise even to the Laureates themselves.

    In 1998, cosmology was shaken at its foundations as two research teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.

    The research teams raced to map the Universe by locating the most distant supernovae. More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors (CCD, Nobel Prize in Physics in 2009), opened the possibility in the 1990s to add more pieces to the cosmological puzzle.

    The teams used a particular kind of supernova, called Type 1a supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected – this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.

    For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.

    The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma – perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.

    *Robert Frost, Fire and Ice, 1920
    ___________________________________________________________________
    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 Albert Einstein’s Theory of General Relativity must be replaced by a new theory of gravity on cosmic scales.

    The Dark Energy Survey 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 Dark Energy Survey 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.
    ___________________________________________________________________
    This is a very powerful telescope located on a mountain top in Chile. Over the years, it has surveyed about 1/8 of the sky and photographed over 300 million galaxies, many of which are so dim, they are about one-millionth as bright as the dimmest stars visible to the human eye. This telescope can image galaxies from the current day to as far back as eight billion years ago. Continuing with the analogy of a 50-year-old individual, DES can take pictures of the Universe starting when it was 21 years old up until the present. (Full disclosure: Researchers at Fermilab, where I also work, carried out this study — but I did not participate in this research.)

    As light from distant galaxies travels to Earth, it can be distorted by galaxies that are closer to us. By using these tiny distortions, astronomers have developed a very precise map of the distribution of matter in the cosmos. This map includes both ordinary matter, of which stars and galaxies are the most familiar examples, and dark matter, which is a hypothesized form of matter that neither absorbs nor emits light. Dark matter is only observed through its gravitational effect on other objects and is thought to be five times more prevalent than ordinary matter.
    __________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., and Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.

    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

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

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

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

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

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

    Dark Matter Research

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory at Stanford University at SNOLAB (Vale Inco Mine, Sudbury, Canada).

    LBNL LZ Dark Matter Experiment xenon detector at Sanford Underground Research Facility Credit: Matt Kapust.


    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

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

    The LBNL LZ Dark Matter Experiment Dark Matter project at SURF, Lead, SD.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington. Credit: Mark Stone U. of Washington. Axion Dark Matter Experiment.

    3
    The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
    __________________________________

    Is the Big Bang incomplete?

    In order to test the Big Bang, astronomers can use measurements taken by the South Pole Telescope and use the theory to project forward to the present day. They can then take measurements from the Dark Energy Survey and compare them. If the measurements are accurate and the theory describes the cosmos, they should agree.

    And, by and large, they do — but not completely. When astronomers look at how “clumpy” the matter of the current Universe should be, purely from SPT measurements and extrapolations of theory, they find that the predictions are “clumpier” than current measurements by DES.

    This disagreement is potentially significant and could signal that the theory of the Big Bang is incomplete. Furthermore, this isn’t the first discrepancy that astronomers have encountered when they project measurements of the same primordial light imaged by the SPT to the modern day. Different research groups, using different telescopes, have found that the current Universe is expanding faster than expected from observations of the ancient light seen by the SPT, combined with Big Bang theory. This other discrepancy is called the Hubble Tension, named after American astronomer Edwin Hubble, who first realized that the Universe was expanding.

    __________________________________________________________________________________

    Edwin Hubble

    .

    __________________________________________________________________________________


    Have astronomers disproved the Big Bang?

    While the new discrepancy in predictions and measurements of the clumpiness of the Universe are preliminary, it could be that both this measurement and the Hubble Tension imply that the Big Bang theory might need some tweaking. Mind you, the discrepancies do not rise to the level of scrapping the theory entirely; however, it is the nature of the scientific method to adjust theories to account for new observations.

    See the full article here.

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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  • richardmitnick 12:50 pm on December 31, 2022 Permalink | Reply
    Tags: "New measurements of galaxy rotation lean toward modified gravity as an explanation for dark matter", , , , , , Dark Matter, , , ,   

    From The Weizmann Institute of Science מכון ויצמן למדע (IL) Via “phys.org” : “New measurements of galaxy rotation lean toward modified gravity as an explanation for dark matter” 

    Weizmann Institute of Science logo

    From The Weizmann Institute of Science מכון ויצמן למדע (IL)

    Via

    “phys.org”

    12.30.22

    Although dark matter is a central part of the standard cosmological model, it’s not without its issues. There continue to be nagging mysteries about the stuff, not the least of which is the fact that scientists have found no direct particle evidence of it.

    Despite numerous searches, we have yet to detect dark matter particles. So some astronomers favor an alternative, such as modified Newtonian dynamics (MoND) or modified gravity model. And a new study of galactic rotation seems to support them.

    ___________________________________________________
    “MOND”: Modified Newtonian dynamics


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


    ___________________________________________________

    The idea of MoND was inspired by galactic rotation. Most of the visible matter in a galaxy is clustered in the middle, so you’d expect that stars closer to the center would have faster orbital speeds than stars farther away, similar to the planets of our solar system. What we observe is that stars in a galaxy all rotate at about the same speed. The rotation curve is essentially flat rather than dropping off. The dark matter solution is that galaxies are surrounded by a halo of invisible matter, but in 1983 Mordehai Milgrom argued that our gravitational model must be wrong.

    At interstellar distances, the gravitational attraction between stars is essentially Newtonian. So rather than modifying General Relativity, Milgrom proposed modifying Newton’s universal law of gravity. He argued that rather than the force of attraction as a pure inverse square relation, gravity has a small remnant pull regardless of distance. This remnant is only about 10 trillionths of a G, but it’s enough to explain galactic rotation curves.

    Of course, just adding a small term to Newton’s gravity means that you also have to modify Einstein’s equations, as well. So MoND has been generalized in various ways, such as AQUAL, which stands for “a quadradic Lagrangian.” Both AQUAL and the standard λCDM model can explain observed galactic rotation curves, but there are some subtle differences.

    This is where a recent study comes in. One difference between AQUAL and λCDM is in the rotation speeds of inner orbit stars vs. outer orbit stars. For λCDM, both should be governed by the distribution of matter, so the curve should be smooth. AQUAL predicts a tiny kink in the curve due to the dynamics of the theory. It’s too small to measure in a single galaxy, but statistically, there should be a small shift between the inner and outer velocity distributions.

    2
    Measured shift between inner and outer stellar motions. Credit: Kyu-Hyun Chae.

    So the author of this paper looked at high-resolution velocity curves of 152 galaxies as observed in the Spitzer Photometry and Accurate Rotation Curves (SPARC) database. He found a shift in agreement with AQUAL. The data seems to support modified gravity over standard dark matter cosmology.

    The result is exciting, but it doesn’t conclusively overturn dark matter. The AQUAL model has its own issues, such as its disagreement with observed gravitational lensing by galaxies. But it is a win for the underdog theory, which has some astronomers cheering “Vive le MoND!”

    The research is published for The Astronomical Journal.

    See the full article here .

    This article originated by Universe Today but heavily modified.

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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    Weizmann Institute Campus

    The Weizmann Institute of Science מכון ויצמן למדע (IL) is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 9:42 am on December 20, 2022 Permalink | Reply
    Tags: "Hunting for Axions in the Galactic Center", A neutron star’s ultrastrong magnetic field could create the conditions for uncloaking a promising dark matter candidate., , Dark Matter, One place axions could show up is in the radio spectra of neutron stars., ,   

    From “Physics” : “Hunting for Axions in the Galactic Center” 

    About Physics

    From “Physics”

    12.13.22
    Charles Day

    A neutron star’s ultrastrong magnetic field could create the conditions for uncloaking a promising dark matter candidate.

    1
    I. Heywood/University of Oxford; SARAO – South African Radio Astronomy Observatory (SA); J. C. Muñoz-Mateos/The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)

    The axion—a hypothetical elementary particle—was originally conceived to solve a puzzle relating to one of the four fundamental forces. Theorists then found another use for this putative particle as a component of dark matter, the mysterious substance that makes up 27% of the Universe’s mass. One place axions could show up is in the radio spectra of neutron stars.

    Now researchers looking for that signature have derived a new upper limit on a key property of axions: how strongly they interact with photons [1].

    One approach to detecting axions is to apply a strong magnetic field to a microwave cavity and then look for a predicted signal of axions converting into photons. In 2009 a pair of astronomers proposed that this conversion could also occur in the plasma threaded by a neutron star’s ultrastrong magnetic field. The conversion is predicted to manifest as a narrow, radio-frequency emission line whose exact frequency depends on the axion mass and whose amplitude depends on the axion density.

    The predicted signal is beyond the reach of current telescopes. However, in 2020 the Massachusetts Institute of Technology’s Joshua Foster and his collaborators demonstrated that it’s possible to derive useful upper limits on the strength of axion-photon conversion by looking for the signal where it’s likely to be strongest: the Galactic Center.

    Now the same team has looked for that signal in data gathered during a search for signatures of intelligent extraterrestrial life. They examine a higher and wider range of axion mass than before (15–35 μ
    eV versus 5–11 μeV) and use a more detailed model of the neutron star population. Evidence of axions remains elusive, but the new interaction-strength bound is more stringent.

    References:

    [1] J. W. Foster et al., “Extraterrestrial axion search with the Breakthrough Listen Galactic Center survey,” Phys. Rev. Lett. 129, 251102 (2022).

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments.

     
  • richardmitnick 9:03 am on December 9, 2022 Permalink | Reply
    Tags: "IGM": intergalactic medium, , "Study explores the possibility that dark photons might be a heat source for intergalactic gas", , , , , Dark Matter, , , , , Tel Aviv University [אוניברסיטת תל אביב](IL), The Institute for Fundamental Physics of the Universe (IT),   

    From The University of Nottingham (UK) And Tel Aviv University [אוניברסיטת תל אביב](IL) And New York University And The Institute for Fundamental Physics of the Universe (IT) Via “phys.org” : “Study explores the possibility that dark photons might be a heat source for intergalactic gas” 

    From The University of Nottingham (UK), and Tel Aviv University [אוניברסיטת תל אביב](IL), and New York University, and The Institute for Fundamental Physics of the Universe (IT)

    Via

    “phys.org”

    12.7.22

    1
    (Top panel) Fit to the Doppler parameter distribution and column density distribution function of the “Lyman-alpha forest” at z=0.1 assuming a maximal contribution of dark photon heating to the line widths. Contours show the projection of the 68% and 95% intervals for the mass and mixing parameter of the dark photon. The colors correspond to different assumptions about the uncertainty of the intergalactic medium temperature at z = 2. (Bottom panel) The corresponding best-fit models compared to the COS observational data. The solid gray curve shows a result with no dark photon heating. Credit: Physical Review Letters (2022).

    Gas clouds across the universe are known to absorb the light produced by distant massive celestial objects, known as quasars.

    This light manifests as the so-called “Lyman alpha forest”, a dense structure composed of absorption lines that can be observed using spectroscopy tools.

    Over the past decades, astrophysicists have been assessing the value of these absorption lines as a tool to better understand the universe and the relationships between cosmological objects. The “Lyman alpha forest” could also potentially aid the ongoing search for dark matter, offering an additional tool to test theoretical predictions and models.

    Researchers at The University of Nottingham (UK), Tel Aviv University [אוניברסיטת תל אביב](IL), New York University, and The Institute for Fundamental Physics of the Universe (IT) have recently compared low-redshift Lyman alpha forest observations to hydrodynamical simulations of the intergalactic medium and dark matter made up of dark photons, a renowned dark matter candidate.

    Their paper, published in Physical Review Letters [below], builds on an earlier work [MNRAS (below)] by some members of their team, which compared simulations of the intergalactic medium (IGM) with “Lyman-alpha forest” measurements collected by the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope.

    “In our analyses, we found that the simulation predicted line widths that were too narrow compared to the COS results, suggesting that there could be additional, noncanonical sources of heating occurring at low redshifts,” Hongwan Liu, Matteo Viel, Andrea Caputo and James Bolton, the researchers who carried out the study, told Phys.org via email.

    “We explored several dark matter models that could act as this source of heating. Building on two of the authors’ experience with dark photons in a previous paper [Physical Review Letters (below)], we eventually realized that heating from dark photon dark matter could work.”

    Based on their previous observations, Liu, Viel, Caputo and Bolton decided to alter a hydrodynamical simulation of the IGM (i.e., a sparse cloud of hydrogen that exists in the spaces between galaxies). In their new simulation, they included the effects of the heat that models predict would be produced by dark photon dark matter.

    “In regions of space where the mass of the dark photon matches the effective plasma mass of the photon, conversions from dark photons to photons can occur,” Liu, Viel, Caputo and Bolton explained. “The converted photons are then rapidly absorbed by the “IGM” in those regions, heating the gas up. The amount of energy transferred from dark matter to the gas can be calculated theoretically.”

    The researchers added this estimated energy transfer between dark photons and intergalactic clouds to their simulations. This ultimately allowed them to attain a series of simulated absorption line widths, which they could compare to actual “Lyman-alpha forest” observations collected by the COS.

    “Broadly speaking, we have shown that the “Lyman-alpha forest” is extremely useful for understanding dark matter models where energy can be converted from dark matter into heating,” Liu, Viel, Caputo and Bolton said. “I think our study will encourage physicists interested in dark matter to pay more attention to the “Lyman-alpha forest”.”

    Overall, the comparison between COS measurements and hydrodynamical simulations performed by this team of researchers suggests that dark photons could in fact be a source of heat in intergalactic gas clouds. Their findings could thus be the first hint of the existence of dark matter that is not observed through its gravitational effects.

    While this is a fascinating possibility, Liu, Viel, Caputo and Bolton have not yet ruled out other possible theoretical explanations. They thus hope that their study will inspire other teams to similarly probe the properties of the “IGM” in the early universe.

    “One particularly interesting consequence of dark photon heating is that underdense regions in the “IGM” are heated up at earlier times compared to overdense regions,” Liu, Viel, Caputo and Bolton said. “This can lead to underdense regions being hotter than overdense regions, which is contrary to standard expectations. There are some indications that the “IGM” does exhibit this behavior at high redshifts. If so, it could be another important piece of evidence in favor of dark photon dark matter heating.”

    Science papers:
    Physical Review Letters
    MNRAS
    Physical Review Letters

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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  • richardmitnick 8:48 pm on December 8, 2022 Permalink | Reply
    Tags: "Unveiling the Universe - In Four New Studies NIST Explores Novel Ways to Hunt Dark Matter", , , Dark Matter, , ,   

    From The National Institute of Standards and Technology: “Unveiling the Universe – In Four New Studies NIST Explores Novel Ways to Hunt Dark Matter” 

    From The National Institute of Standards and Technology

    12.8.22

    Media Contact
    Rich Press
    richard.press@nist.gov
    (301) 975-0501

    Technical Contact
    Jacob Taylor
    jacob.taylor@nist.gov
    (301) 975-8586

    Marianna Safronova
    marianna.safronova@nist.gov

    For decades, astronomers and physicists have been trying to solve one of the deepest mysteries about the cosmos: An estimated 85% of its mass is missing. Numerous astronomical observations indicate that the visible mass in the universe is not nearly enough to hold galaxies together and account for how matter clumps. Some kind of invisible, unknown type of subatomic particle, dubbed dark matter, must provide the extra gravitational glue.

    In underground laboratories and at particle accelerators, scientists have been searching for this dark matter with no success for more than 30 years.
    __________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., and Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.

    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

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

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

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

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

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

    Dark Matter Research

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory at Stanford University at SNOLAB (Vale Inco Mine, Sudbury, Canada).

    LBNL LZ Dark Matter Experiment xenon detector at Sanford Underground Research Facility Credit: Matt Kapust.


    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

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

    The LBNL LZ Dark Matter Experiment Dark Matter project at SURF, Lead, SD.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington. Credit: Mark Stone U. of Washington. Axion Dark Matter Experiment.

    3
    The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
    __________________________________

    Researchers at NIST are now exploring new ways to search for the invisible particles. In one study, a prototype for a much larger experiment, researchers have used state-of-the-art superconducting detectors to hunt for dark matter. The study has already placed new limits on the possible mass of one type of hypothesized dark matter. Another NIST team has proposed that trapped electrons, commonly used to measure properties of ordinary particles, could also serve as highly sensitive detectors of hypothetical dark matter particles if they carry charge.

    In the superconducting detector study, NIST scientists Jeff Chiles and Sae Woo Nam and their collaborators used tungsten silicide superconducting nanowires only one-thousandth the width of a human hair as dark-matter detectors.

    1
    NIST scientists Jeff Chiles and Sae Woo Nam and their collaborators used tungsten silicide superconducting nanowires only one-thousandth the width of a human hair as dark-matter detectors.

    “Superconducting” refers to a property that some materials, such as tungsten silicide, have at ultralow temperatures: zero resistance to the flow of electrical current. Systems of such wires, formally known as superconducting nanowire single-photon detectors (SNSPDs), are exquisitely sensitive to extremely small amounts of energy imparted by photons (particles of light) and perhaps dark matter particles when they collide with the detectors.

    Although the experiment would have to be performed on a larger scale with many more detectors to provide an expanded dataset, it is still the most sensitive search for dark photons performed to date in this mass range, Nam said. The researchers, including collaborators from the Massachusetts Institute of Technology, Stanford University, University of Washington, New York University and the Flatiron Institute, reported their results in an article in Physical Review Letters [below] posted on June 10.

    In a second report, some of the same NIST researchers and their collaborators analyzed data from the first study in a different way. The scientists ignored potential effects of the stack of insulating material and focused only on whether any kind of dark matter particles would be capable of interacting with individual electrons in the nanowire detector itself — either by scattering off an electron or being absorbed by it. Although small, this study has placed the strongest limits of any experiment to date — excluding astrophysical searches and studies of the sun — on the strength of interactions between electrons and dark matter in the sub-million-eV mass range. That makes it likely that a scaled-up version of the SNSPD setup could make a significant contribution to the search for dark matter, said Chiles. He and his colleagues from the Hebrew University of Jerusalem, the University of California-Santa Cruz, the University of California’s Santa Cruz Institute for Particle Physics; and MIT reported this analysis in an article in the Dec. 8 edition of Physical Review D [below].

    In a third study, a NIST physicist and his colleagues proposed that single electrons, electromagnetically confined to a small region of space, could be sensitive detectors of charged dark matter particles. For more than three decades, scientists have used a much heavier population of positively charged beryllium ions to probe the electric and magnetic properties of ordinary (non-dark) charged particles. Electrons, however, would make ideal detectors for sensing dark matter particles if those particles have even the slightest electric charge. That’s because electrons have the lowest mass of any charged particle known and therefore are easily pushed or pulled by the merest electrical disturbance, such as a particle with a small electric charge passing nearby. Only a few single trapped electrons would be needed to detect charged dark matter particles with only one-hundredth the charge of an electron, said NIST physicist Jake Taylor, a fellow of the Joint Quantum Institute and the Joint Center for Quantum Information and Computer Science, research partnerships between NIST and the University of Maryland. The electromagnetically trapped electrons would be cooled to a fraction of a degree above absolute zero in order to limit the particle’s inherent jitter. Taylor, along with Daniel Carney of The DOE’s Lawrence Berkeley National Laboratory in California, Hartmut Haffner of the University of California- Berkeley, and David C. Moore of Yale University, described their proposed experiment in a Physical Review Letters [below] article posted online last August. By configuring the trap so that the strength of the electron’s confinement is different along each dimension — length, width and height — the trap could potentially also provide information about the direction from which the dark matter particle arrived. However, scientists must grapple with a technological challenge before they can employ electron trapping to search for dark matter. Photons are used to cool, manipulate and sense the motion of trapped ions and electrons. For beryllium ions, those photons — generated by a laser — fall in the range of visible light. The technology that enables visible-light photons to manipulate trapped beryllium ions is well established. In contrast, the photons required to sense the motion of single electrons have microwave energies, and the necessary detection technology has yet to be perfected. However, if interest in the project is strong enough, scientists might develop an electron trap capable of detecting dark matter in less than five years, Carney estimated.

    In the fourth study, a NIST researcher and an international group of colleagues are looking beyond Earth to hunt for dark matter. A team that includes Marianna Safronova of the University of Delaware and the Joint Quantum Institute has proposed that a new generation of atomic clocks, installed on a spacecraft that would fly closer to the Sun than Mercury’s orbit, could search for signs of ultralight dark matter. This hypothetical type of dark matter, bound to a halo surrounding the Sun, would cause tiny variations in the fundamental constants of nature, including the mass of the electron and the fine structure constant. Changes in these constants would alter the frequency at which atomic clocks vibrate — the rate at which they “tick.” Among the large variety of atomic clocks, researchers would carefully choose two that have different sensitivities to changes in the fundamental constants driven by ultralight dark matter. By measuring the ratio of the two varying frequencies, scientists could reveal the presence of the dark matter, the researchers calculated. They describe their analysis in an article posted online Dec. 5 in Nature Astronomy [below].

    Science papers:
    Physical Review Letters
    Physical Review D
    Physical Review Letters 2021
    Nature Astronomy

    See the full article here.

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    NIST Campus, Gaitherberg, MD.

    The National Institute of Standards and Technology‘s Mission, Vision, Core Competencies, and Core Values

    Mission

    To promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.

    NIST’s vision

    NIST will be the world’s leader in creating critical measurement solutions and promoting equitable standards. Our efforts stimulate innovation, foster industrial competitiveness, and improve the quality of life.

    NIST’s core competencies

    Measurement science
    Rigorous traceability
    Development and use of standards

    NIST’s core values

    NIST is an organization with strong values, reflected both in our history and our current work. NIST leadership and staff will uphold these values to ensure a high performing environment that is safe and respectful of all.

    Perseverance: We take the long view, planning the future with scientific knowledge and imagination to ensure continued impact and relevance for our stakeholders.
    Integrity: We are ethical, honest, independent, and provide an objective perspective.
    Inclusivity: We work collaboratively to harness the diversity of people and ideas, both inside and outside of NIST, to attain the best solutions to multidisciplinary challenges.
    Excellence: We apply rigor and critical thinking to achieve world-class results and continuous improvement in everything we do.

    Background

    The Articles of Confederation, ratified by the colonies in 1781, contained the clause, “The United States in Congress assembled shall also have the sole and exclusive right and power of regulating the alloy and value of coin struck by their own authority, or by that of the respective states—fixing the standards of weights and measures throughout the United States”. Article 1, section 8, of the Constitution of the United States (1789), transferred this power to Congress; “The Congress shall have power…To coin money, regulate the value thereof, and of foreign coin, and fix the standard of weights and measures”.

    In January 1790, President George Washington, in his first annual message to Congress stated that, “Uniformity in the currency, weights, and measures of the United States is an object of great importance, and will, I am persuaded, be duly attended to”, and ordered Secretary of State Thomas Jefferson to prepare a plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States, afterwards referred to as the Jefferson report. On October 25, 1791, Washington appealed a third time to Congress, “A uniformity of the weights and measures of the country is among the important objects submitted to you by the Constitution and if it can be derived from a standard at once invariable and universal, must be no less honorable to the public council than conducive to the public convenience”, but it was not until 1838, that a uniform set of standards was worked out. In 1821, John Quincy Adams had declared “Weights and measures may be ranked among the necessities of life to every individual of human society”.

    From 1830 until 1901, the role of overseeing weights and measures was carried out by the Office of Standard Weights and Measures, which was part of the U.S. Coast and Geodetic Survey in the Department of the Treasury.

    Bureau of Standards

    In 1901 in response to a bill proposed by Congressman James H. Southard (R- Ohio) the National Bureau of Standards was founded with the mandate to provide standard weights and measures and to serve as the national physical laboratory for the United States. (Southard had previously sponsored a bill for metric conversion of the United States.)

    President Theodore Roosevelt appointed Samuel W. Stratton as the first director. The budget for the first year of operation was $40,000. The Bureau took custody of the copies of the kilogram and meter bars that were the standards for US measures, and set up a program to provide metrology services for United States scientific and commercial users. A laboratory site was constructed in Washington DC (US) and instruments were acquired from the national physical laboratories of Europe. In addition to weights and measures the Bureau developed instruments for electrical units and for measurement of light. In 1905 a meeting was called that would be the first National Conference on Weights and Measures.

    Initially conceived as purely a metrology agency the Bureau of Standards was directed by Herbert Hoover to set up divisions to develop commercial standards for materials and products. Some of these standards were for products intended for government use; but product standards also affected private-sector consumption. Quality standards were developed for products including some types of clothing; automobile brake systems and headlamps; antifreeze; and electrical safety. During World War I, the Bureau worked on multiple problems related to war production even operating its own facility to produce optical glass when European supplies were cut off. Between the wars Harry Diamond of the Bureau developed a blind approach radio aircraft landing system. During World War II military research and development was carried out including development of radio propagation forecast methods; the proximity fuze and the standardized airframe used originally for Project Pigeon; and shortly afterwards the autonomously radar-guided Bat anti-ship guided bomb and the Kingfisher family of torpedo-carrying missiles.

    In 1948, financed by the United States Air Force the Bureau began design and construction of SEAC: the Standards Eastern Automatic Computer. The computer went into operation in May 1950 using a combination of vacuum tubes and solid-state diode logic. About the same time the Standards Western Automatic Computer, was built at the Los Angeles office of the NBS by Harry Huskey and used for research there. A mobile version- DYSEAC- was built for the Signal Corps in 1954.

    Due to a changing mission, the “National Bureau of Standards” became the “ The National Institute of Standards and Technology” in 1988.

    Following September 11, 2001, NIST conducted the official investigation into the collapse of the World Trade Center buildings.

    Organization

    NIST is headquartered in Gaithersburg, Maryland, and operates a facility in Boulder, Colorado, which was dedicated by President Eisenhower in 1954. NIST’s activities are organized into laboratory programs and extramural programs. Effective October 1, 2010, NIST was realigned by reducing the number of NIST laboratory units from ten to six. NIST Laboratories include:

    Communications Technology Laboratory (CTL)
    Engineering Laboratory (EL)
    Information Technology Laboratory (ITL)
    Center for Neutron Research (NCNR)
    Material Measurement Laboratory (MML)
    Physical Measurement Laboratory (PML)

    Extramural programs include:

    Hollings Manufacturing Extension Partnership (MEP), a nationwide network of centers to assist small and mid-sized manufacturers to create and retain jobs, improve efficiencies, and minimize waste through process improvements and to increase market penetration with innovation and growth strategies;
    Technology Innovation Program (TIP), a grant program where NIST and industry partners cost share the early-stage development of innovative but high-risk technologies;
    Baldrige Performance Excellence Program, which administers the Malcolm Baldrige National Quality Award, the nation’s highest award for performance and business excellence.

    NIST’s Boulder laboratories are best known for NIST‑F1 which houses an atomic clock.

    NIST‑F1 serves as the source of the nation’s official time. From its measurement of the natural resonance frequency of cesium—which defines the second—NIST broadcasts time signals via longwave radio station WWVB near Fort Collins in Colorado, and shortwave radio stations WWV and WWVH, located near Fort Collins and Kekaha in Hawai’i, respectively.

    NIST also operates a neutron science user facility: the NIST Center for Neutron Research (NCNR).

    The NCNR provides scientists access to a variety of neutron scattering instruments which they use in many research fields (materials science; fuel cells; biotechnology etc.).

    The SURF III Synchrotron Ultraviolet Radiation Facility is a source of synchrotron radiation in continuous operation since 1961.

    SURF III now serves as the US national standard for source-based radiometry throughout the generalized optical spectrum. All NASA-borne extreme-ultraviolet observation instruments have been calibrated at SURF since the 1970s, and SURF is used for measurement and characterization of systems for extreme ultraviolet lithography.

    The Center for Nanoscale Science and Technology performs research in nanotechnology, both through internal research efforts and by running a user-accessible cleanroom nanomanufacturing facility.

    This “NanoFab” is equipped with tools for lithographic patterning and imaging (e.g., electron microscopes and atomic force microscopes).
    Committees

    NIST has seven standing committees:

    Technical Guidelines Development Committee (TGDC)
    Advisory Committee on Earthquake Hazards Reduction (ACEHR)
    National Construction Safety Team Advisory Committee (NCST Advisory Committee)
    Information Security and Privacy Advisory Board (ISPAB)
    Visiting Committee on Advanced Technology (VCAT)
    Board of Overseers for the Malcolm Baldrige National Quality Award (MBNQA Board of Overseers)
    Manufacturing Extension Partnership National Advisory Board (MEPNAB)

    Measurements and standards

    As part of its mission, NIST supplies industry, academia, government, and other users with over 1,300 Standard Reference Materials (SRMs). These artifacts are certified as having specific characteristics or component content, used as calibration standards for measuring equipment and procedures, quality control benchmarks for industrial processes, and experimental control samples.

    Handbook 44

    NIST publishes the Handbook 44 each year after the annual meeting of the National Conference on Weights and Measures (NCWM). Each edition is developed through cooperation of the Committee on Specifications and Tolerances of the NCWM and the Weights and Measures Division (WMD) of the NIST. The purpose of the book is a partial fulfillment of the statutory responsibility for “cooperation with the states in securing uniformity of weights and measures laws and methods of inspection”.

    NIST has been publishing various forms of what is now the Handbook 44 since 1918 and began publication under the current name in 1949. The 2010 edition conforms to the concept of the primary use of the SI (metric) measurements recommended by the Omnibus Foreign Trade and Competitiveness Act of 1988.

     
  • richardmitnick 5:33 pm on December 5, 2022 Permalink | Reply
    Tags: "Detecting dark matter with quantum computers", , , Dark Matter, Dark matter makes up about 27% of the matter and energy budget in the universe but scientists do not know much about it., , How quantum computers could detect dark matter, It is difficult to detect dark matter directly because it does not interact with light., , , Scientists at the DOE's Fermi National Accelerator Laboratory have found a way to look for dark matter using quantum computers., , , Using qubits-the main component of quantum computing systems-to detect single photons produced by dark matter in the presence of a strong magnetic field., When dark matter particles traverse a strong magnetic field they may produce photons scientists can measure with superconducting qubits inside aluminum photon cavities.   

    From The DOE’s Fermi National Accelerator Laboratory: “Detecting dark matter with quantum computers” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From The DOE’s Fermi National Accelerator Laboratory-an enduring source of strength for the US contribution to scientific research worldwide.

    12.5.22
    Emily Driehaus

    Dark matter makes up about 27% of the matter and energy budget in the universe but scientists do not know much about it. They do know that it is cold, meaning that the particles that make up dark matter are slow-moving. It is also difficult to detect dark matter directly because it does not interact with light. However, scientists at the U.S. Department of Energy’s Fermi National Accelerator Laboratory have found a way to look for dark matter using quantum computers.

    Aaron Chou, a senior scientist at Fermilab, works on detecting dark matter through quantum science. As part of DOE’s Office of High Energy Physics QuantISED program, he has developed a way to use qubits, the main component of quantum computing systems, to detect single photons produced by dark matter in the presence of a strong magnetic field.

    How quantum computers could detect dark matter

    A classical computer processes information with binary bits set to either 1 or 0. The specific pattern of ones and zeros makes it possible for the computer to perform certain functions and tasks. In quantum computing, however, qubits exist at both 1 and 0 simultaneously until they are read, due to a quantum mechanical property known as superposition. This property allows quantum computers to efficiently perform complex calculations that a classical computer would take an enormous amount of time to complete.

    “Qubits work by manipulating single excitations of information, for example, single photons,” said Chou. “So, if you’re working with such small packets of energy as single excitations, you’re far more susceptible to external disturbances.”

    1
    Akash Dixit works on the team that uses quantum computers to look for dark matter. Here, Dixit holds a microwave cavity containing a superconducting qubit. The cavity has holes in its side in the same way the screen on a microwave oven door has holes; the holes are simply too small for microwaves to escape. Photo: Ryan Postel, Fermilab.

    In order for qubits to operate at these quantum levels, they must reside in carefully controlled environments that protect them from outside interference and keep them at consistently cold temperatures. Even the slightest disturbance can throw off a program in a quantum computer. With their extreme sensitivity, Chou realized quantum computers could provide a way to detect dark matter. He recognized that other dark matter detectors need to be shielded in the same way quantum computers are, further solidifying the idea.

    “Both quantum computers and dark matter detectors have to be heavily shielded, and the only thing that can jump through is dark matter,” Chou said. “So, if people are building quantum computers with the same requirements, we asked ‘why can’t you just use those as dark matter detectors?’”

    Where errors are most welcome

    When dark matter particles traverse a strong magnetic field, they may produce photons that Chou and his team can measure with superconducting qubits inside aluminum photon cavities. Because the qubits have been shielded from all other outside disturbances, when scientists detect a disturbance from a photon, they can infer that it was the result of dark matter flying through the protective layers.

    “These disturbances manifest as errors where you didn’t load any information into the computer, but somehow information appeared, like zeroes that flip into ones from particles flying through the device,” he said.

    2
    Scientist Aaron Chou leads the experiment that searches for dark matter using superconducting qubits and cavities. Photo: Ryan Postel, Fermilab.

    So far, Chou and his team have demonstrated how the technique works and that the device is incredibly sensitive to these photons. Their method has advantages over other sensors, such as being able to make multiple measurements of the same photon to ensure a disturbance was not just caused by another fluke. The device also has an ultra-low noise level, which allows for a heightened sensitivity to dark matter signals.

    “We know how to make these tunable boxes from the high-energy physics community, and we worked together with the quantum computing people to understand and transfer the technology for these qubits to be used as sensors,” Chou said.

    From here, they plan to develop a dark matter detection experiment and continue improving upon the design of the device.

    Using sapphire cavities to catch dark matter

    3
    These new sapphire photon cavities will help lead the team closer to running dark matter experiments that combine aspects from both physics and quantum science. Photo: Ankur Agrawal, University of Chicago.

    “This apparatus tests the sensor in the box, which holds photons with a single frequency,” Chou said. “The next step is to modify this box to turn it into kind of a radio receiver in which we can change the dimensions of the box.”

    By altering the dimensions of the photon cavity, it will be able to sense different wavelengths of photons produced by dark matter.

    “The waves that can live in the box are determined by the overall size of the box. In order to change what frequencies and which wavelengths of dark matter we want to look for, we actually have to change the size of the box,” said Chou. “That’s the work we’re currently doing; we’ve created boxes in which we can change the lengths of different parts of it in order to be able to tune into dark matter at different frequencies.”

    The researchers are also developing cavities made from different materials. The traditional aluminum photon cavities lose their superconductivity in the presence of the magnetic field necessary for producing photons from dark matter particles.

    “These cavities cannot live in high magnetic fields,” he said. “High magnetic fields destroy the superconductivity, so we’ve made a new cavity made out of synthetic sapphire.”

    Developing these new, tunable sapphire photon cavities will lead the team closer to running dark matter experiments that combine aspects from both physics and quantum science.

    __________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., and Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

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

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

    Dark Matter Research

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory at Stanford University at SNOLAB (Vale Inco Mine, Sudbury, Canada).

    LBNL LZ Dark Matter Experiment xenon detector at Sanford Underground Research Facility Credit: Matt Kapust.


    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

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

    The LBNL LZ Dark Matter Experiment Dark Matter project at SURF, Lead, SD.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.

    3
    The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
    __________________________________

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The DOE’s Fermi National Accelerator Laboratory, located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association. Fermilab is a part of the Illinois Technology and Research Corridor.

    Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL)[CERN] Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

    In addition to high-energy collider physics, Fermilab hosts a series of fixed-target and neutrino experiments, such as The MicroBooNE (Micro Booster Neutrino Experiment),

    NOνA (NuMI Off-Axis νe Appearance)

    and Seaquest

    .

    Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment).

    The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year.

    SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector.

    The ICARUS neutrino experiment was moved from CERN to Fermilab.

    In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.

    Asteroid 11998 Fermilab is named in honor of the laboratory.

    The DOE’s Fermi National Accelerator Laboratory campus.

    The DOE’s Fermi National Accelerator Laboratory/MINERvA. Photo Reidar Hahn.

    The DOE’s Fermi National Accelerator LaboratoryDAMIC | The Fermilab Cosmic Physics Center.

    The DOE’s Fermi National Accelerator LaboratoryMuon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles.

    The DOE’s Fermi National Accelerator Laboratory Short-Baseline Near Detector under construction.

    The DOE’s Fermi National Accelerator Laboratory Mu2e solenoid.

    The Dark Energy Camera [DECam], built at The DOE’s Fermi National Accelerator Laboratory.

    Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

    The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.

    After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.

    The later directors include:

    John Peoples, 1989 to 1996
    Michael S. Witherell, July 1999 to June 2005
    Piermaria Oddone, July 2005 to July 2013
    Nigel Lockyer, September 2013 to the present

    Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid and hosts 1000 U.S. scientists who work on the CMS project.

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  • richardmitnick 3:07 pm on December 5, 2022 Permalink | Reply
    Tags: "An Unexpected Source Might Be Helping The Universe Glow More Than It Should", , A potential explanation for the cosmic optical background [COB] excess that is allowed by independent observational constraints., , , , , Dark Matter, Galaxies rotate faster than they should under the gravity generated by the mass of visible matter [see Coma Cluster]., Roughly 80 percent of the matter in the Universe is dark matter., , , Very very faintly the space between the stars was glowing with optical light., When the New Horizons probe reached the outer dark of the Solar System out past Pluto its instruments picked up something strange.   

    From The Johns Hopkins University Via “Science Alert (AU)” : “An Unexpected Source Might Be Helping The Universe Glow More Than It Should” 

    From The Johns Hopkins University

    Via

    ScienceAlert

    “Science Alert (AU)”

    12.5.22
    Michelle Starr

    When the New Horizons probe reached the outer dark of the Solar System out past Pluto its instruments picked up something strange.

    Very very faintly the space between the stars was glowing with optical light. This in itself was not unexpected; this light is called the cosmic optical background [COB], a faint luminescence from all the light sources in the Universe outside our galaxy [Nature Communications (below)].

    Figure 1: The trajectory of New Horizons through the solar system.
    2
    Data collection periods of relevance to this study are indicated. Both the x−y and r−z planes are shown (a,b, respectively), with the axes in solar ecliptic units [see formula in Nature Communications paper below]. New Horizons was launched from Earth at 1 a.u., and the data with the LORRI dust cover in place were acquired at 1.9 a.u., just beyond Mars’ orbit at 1.5 a.u. (inner blue dotted lines). The dust cover was ejected near 3.6 a.u., and the data were acquired before and during an encounter with Jupiter. The data considered here were taken between 2007 and 2010 while New Horizons was in cruise phase. The red vectors indicate the relative positions of fields 1−4 compared to the sun and plane of the ecliptic.

    Figure 2: Measurements of the COB surface brightness.
    3
    The [see formula in Nature Communications paper below] determined in this study are shown as both an upper limit (red) and a mean (red star). We also show previous results in the literature, including direct constraints on the COB (filled symbols) and the IGL (open symbols). The plotted LORRI errors are purely statistical and are calculated from the observed variance in the mean of individual 10 s exposures; see Fig. 3 for an assessment of the systematic uncertainties in the measurement. We include the measurements from HST-WFPC2 (ref. 7; green squares), combinations of DIRBE and 2MASS10,11,12,13 (diamonds; the wavelengths of these measurements have been shifted for clarity), a measurement using the ‘dark cloud’ method8 (grey circles), and previous Pioneer 10/11 measurements22,23 (blue upper limit leader and circles). The gold region indicates the H.E.S.S. constraints on the extragalactic background light29. We include the background inferred from CIBER5 (pentagons). The IGL points are compiled from HST-STIS in the ultraviolet (UV)62 (open square), and the Hubble Deep Field63 (downward open triangles) the Subaru Deep Field64,65 (upward open triangles and sideways pointing triangles) in the optical/near-IR. Where plotted, horizontal bars indicate the effective wavelength band of the measurement. Our new LORRI value from just 260 s of integration time is consistent with the previous Pioneer values.

    The strange part was the amount of light. There was significantly more than scientists thought there should be – twice as much, in fact.

    Now, in a new paper [PRL (below)], scientists lay out a possible explanation for the optical light excess: a by-product of an otherwise undetectable interaction of dark matter.

    “The results of this work,” write a team of researchers led by astrophysicist José Luis Bernal of Johns Hopkins University, “provide a potential explanation for the cosmic optical background [COB] excess that is allowed by independent observational constraints, and that may answer one of the most long-standing unknowns in cosmology: the nature of dark matter.”

    We have many questions about the Universe, but dark matter is among the most vexing. It’s the name we give to a mysterious mass in the Universe responsible for providing far more gravity in concentrated spots than there ought to be.

    Galaxies rotate faster than they should under the gravity generated by the mass of visible matter.

    The curvature of space-time around massive objects is greater than it should be if we calculated the warping of space based only on the amount of glowing material.

    But whatever it is creating this effect, we can’t detect it directly. The only way we know it’s there is that we just can’t account for this extra gravity.

    And there’s a lot of it. Roughly 80 percent of the matter in the Universe is dark matter.

    __________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., and Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

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

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

    Dark Matter Research

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory at Stanford University at SNOLAB (Vale Inco Mine, Sudbury, Canada).

    LBNL LZ Dark Matter Experiment xenon detector at Sanford Underground Research Facility Credit: Matt Kapust.


    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

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

    The LBNL LZ Dark Matter Experiment Dark Matter project at SURF, Lead, SD.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    Inside the Axion Dark Matter eXperiment U Washington Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.

    3
    The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
    __________________________________

    There are some hypotheses about what it might be. One of the candidates is the axion, which belongs to a hypothetical class of particles first conceptualized in the 1970s to resolve the question of why strong atomic forces follow something called charge-parity symmetry when most models say they don’t need to.

    [See ADMX above]

    As it turns out, axions in a specific mass range should also behave exactly like we expect dark matter to. And there might be a way to detect them – because theoretically, axions are expected to decay into pairs of photons in the presence of a strong magnetic field.

    Several experiments are searching for sources of these photons, but they should also be streaming through space in excess numbers.

    The difficulty is in separating them from all the other sources of light in the Universe, and this is where the cosmic optical background comes in.

    The background is itself very difficult to detect since it’s so faint. The Long Range Reconnaissance Imager (LORRI) aboard the New Horizons is possibly the best tool for the job yet. It’s far from Earth and the Sun, and LORRI is far more sensitive than instruments attached to the more distant Voyager probes that launched 40 years earlier.

    Scientists have presumed the excess detected by New Horizons to be the product attributed to stars and galaxies that we can’t see. And that option is still very much on the table. The work of Bernal and his team was to assess whether axion-like dark matter could possibly be responsible for the extra light.

    They conducted mathematical modeling and determined that axions with masses between 8 and 20 electronvolts could produce the observed signal under certain conditions.

    That’s incredibly light for a particle, which tends to be measured in megaelectronvolts. But with recent estimates putting the hypothetical piece of matter at a fraction of a single electronvolt, these numbers would demand axions to be relatively beefy.

    It’s impossible to tell which explanation is correct based solely on the current data. However, by narrowing down the masses of the axions that could be responsible for the excess, the researchers have laid the foundations for future searches for these enigmatic particles.

    “If the excess arises from dark-matter decay to a photon line, there will be a significant signal in forthcoming line-intensity mapping measurements,” the researchers write.

    “Moreover, the ultraviolet instrument aboard New Horizons (which will have better sensitivity and probe a different range of the spectrum) and future studies of very high-energy gamma-ray attenuation will also test this hypothesis and expand the search for dark matter to a wider range of frequencies.”

    The research has been published in Physical Review Letters.

    Science paper:
    Nature Communications 2017
    See the science paper for instructive material with more images.

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

    The Johns Hopkins University is a private research university in Baltimore, Maryland. Founded in 1876, the university was named for its first benefactor, the American entrepreneur and philanthropist Johns Hopkins. His $7 million bequest (approximately $147.5 million in today’s currency)—of which half financed the establishment of the Johns Hopkins Hospital—was the largest philanthropic gift in the history of the United States up to that time. Daniel Coit Gilman, who was inaugurated as the institution’s first president on February 22, 1876, led the university to revolutionize higher education in the U.S. by integrating teaching and research. Adopting the concept of a graduate school from Germany’s historic Ruprecht Karl University of Heidelberg, [Ruprecht-Karls-Universität Heidelberg] (DE), Johns Hopkins University is considered the first research university in the United States. Over the course of several decades, the university has led all U.S. universities in annual research and development expenditures. In fiscal year 2016, Johns Hopkins spent nearly $2.5 billion on research. The university has graduate campuses in Italy, China, and Washington, D.C., in addition to its main campus in Baltimore.

    Johns Hopkins is organized into 10 divisions on campuses in Maryland and Washington, D.C., with international centers in Italy and China. The two undergraduate divisions, the Zanvyl Krieger School of Arts and Sciences and the Whiting School of Engineering, are located on the Homewood campus in Baltimore’s Charles Village neighborhood. The medical school, nursing school, and Bloomberg School of Public Health, and Johns Hopkins Children’s Center are located on the Medical Institutions campus in East Baltimore. The university also consists of the Peabody Institute, Applied Physics Laboratory, Paul H. Nitze School of Advanced International Studies, School of Education, Carey Business School, and various other facilities.

    Johns Hopkins was a founding member of the American Association of Universities. As of October 2019, 39 Nobel laureates and 1 Fields Medalist have been affiliated with Johns Hopkins. Founded in 1883, the Blue Jays men’s lacrosse team has captured 44 national titles and plays in the Big Ten Conference as an affiliate member as of 2014.

    Research

    The opportunity to participate in important research is one of the distinguishing characteristics of Hopkins’ undergraduate education. About 80 percent of undergraduates perform independent research, often alongside top researchers. In FY 2013, Johns Hopkins received $2.2 billion in federal research grants—more than any other U.S. university for the 35th consecutive year. Johns Hopkins has had seventy-seven members of the Institute of Medicine, forty-three Howard Hughes Medical Institute Investigators, seventeen members of the National Academy of Engineering, and sixty-two members of the National Academy of Sciences. As of October 2019, 39 Nobel Prize winners have been affiliated with the university as alumni, faculty members or researchers, with the most recent winners being Gregg Semenza and William G. Kaelin.

    Between 1999 and 2009, The Johns Hopkins University was among the most cited institutions in the world. It attracted nearly 1,222,166 citations and produced 54,022 papers under its name, ranking No. 3 globally [after Harvard University and the Max Planck Society (DE)] in the number of total citations published in Thomson Reuters-indexed journals over 22 fields in America.

    In FY 2000, Johns Hopkins received $95.4 million in research grants from the National Aeronautics and Space Administration, making it the leading recipient of NASA research and development funding. In FY 2002, Hopkins became the first university to cross the $1 billion threshold on either list, recording $1.14 billion in total research and $1.023 billion in federally sponsored research. In FY 2008, Johns Hopkins University performed $1.68 billion in science, medical and engineering research, making it the leading U.S. academic institution in total R&D spending for the 30th year in a row, according to a National Science Foundation ranking. These totals include grants and expenditures of JHU’s Applied Physics Laboratory in Laurel, Maryland.

    The Johns Hopkins University also offers the “Center for Talented Youth” program—a nonprofit organization dedicated to identifying and developing the talents of the most promising K-12 grade students worldwide. As part of the Johns Hopkins University, the “Center for Talented Youth” or CTY helps fulfill the university’s mission of preparing students to make significant future contributions to the world. The Johns Hopkins Digital Media Center (DMC) is a multimedia lab space as well as an equipment, technology and knowledge resource for students interested in exploring creative uses of emerging media and use of technology.

    In 2013, the Bloomberg Distinguished Professorships program was established by a $250 million gift from Michael Bloomberg. This program enables the university to recruit fifty researchers from around the world to joint appointments throughout the nine divisions and research centers. For The American Academy of Arts and Sciences each professor must be a leader in interdisciplinary research and be active in undergraduate education. Directed by Vice Provost for Research Denis Wirtz, there are currently thirty-two Bloomberg Distinguished Professors at the university, including three Nobel Laureates, eight fellows of the American Association for the Advancement of Science, ten members of the American Academy of Arts and Sciences, and thirteen members of the National Academies.

     
  • richardmitnick 11:11 am on December 2, 2022 Permalink | Reply
    Tags: , "Study rules out initially clustered primordial black holes as dark matter candidates", , , , , , Dark Matter, La Sapienza University of Rome [Sapienza Università di Roma](IT), , , The National Institute of Chemical Physics and Biophysics [Keemilise ja Bioloogilise Füüsika Instituut] (EE),   

    From The University of Geneva [Université de Genève](CH) And La Sapienza University of Rome [Sapienza Università di Roma](IT) And The National Institute of Chemical Physics and Biophysics [Keemilise ja Bioloogilise Füüsika Instituut] (EE) Via “phys.org” : “Study rules out initially clustered primordial black holes as dark matter candidates” 

    From “phys.org”

    12.1.22
    Ingrid Fadelli

    Primordial black holes (PBHs) are fascinating cosmic bodies that have been widely investigated by astrophysicists worldwide. As suggested by their name, these are black holes believed to have appeared in the universe’s early days, less than a second after the Big Bang.

    Physics theory suggests that within the fraction of a second before the universe was formed, space was not completely homogeneous, thus denser and hotter regions could have collapsed into black holes. Depending on when exactly they were formed within this fraction of a second, these PBHs could have very different masses and associated characteristics.

    Some theoretical physicists have been exploring the possibility that PBHs contribute significantly to the predicted abundance of dark matter in the universe, or in other words, that they are major dark matter candidates. Gravitational wave observations gathered by the LIGO-Virgo-KAGRA collaboration and constraints set by these observations suggest that this is highly unlikely.
    ___________________________________________________________________
    LIGO-VIRGO-KAGRA-GEO 600-LIGO-India-ESA/NASA LISA

    Caltech /MIT Advanced aLigo.

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

    Caltech/MIT Advanced aLigo Hanford, WA. installation.

    VIRGO Gravitational Wave interferometer installation, near Pisa (IT).

    KAGRA Large-scale Cryogenic Gravitational Wave Telescope Project installation (JP).


    ___________________________________________________________________


    ___________________________________________________________________

    Yet some recent studies suggested that the clustering of PBHs at the time of their formation could change their merger rate, which would potentially enable values within the constraints set by LIGO-Virgo-KAGRA. This clustering would also potentially affect existing microlensing bounds, as PBH clusters would act as a massive single lens that cannot be probed by microlensing studies.

    Researchers at The University of Geneva [Université de Genève](CH), La Sapienza University of Rome [Sapienza Università di Roma](IT) and The National Institute of Chemical Physics and Biophysics [Keemilise ja Bioloogilise Füüsika Instituut] (EE) have recently carried out a theoretical study further assessing the hypothesis that initially clustered PBHs could be dark matter candidates. Their paper, published in Physical Review Letters [below], introduces a relatively simple argument that appears to rule out this possibility.

    “Our work was motivated by the claim, not yet proven by literature, that primordial black holes with masses around the solar masses could avoid the current strong constraints coming from microlensing, if they were strongly clustered,” Antonio Riotto, one of the researchers who carried out the study, told Phys.org.

    “Our study proved that this claim is not correct. The idea is simple: clustered PBHs may avoid the microlensing bound if the clustering is strong enough, but this would be at odds with another set of data coming from Lyman-alpha forest, which suggests that this would require weak clustering.”

    In their analyses, Riotto and his colleagues combined the constraints from microlensing set by previous astronomical observations with Lyman-alpha forest data. The Lyman-alpha forest is an absorption phenomenon that can be observed using astronomical spectroscopy tools, presenting itself as absorption lines in the spectra of distant galaxies and quasars.

    These absorption lines have become a prominent probe in astrophysics, particularly in studies investigating density fluctuations in the Universe. In their paper, the researchers showed that Lyman-alpha forest data suggests that in order to avoid existing microlensing bounds, PBHs would need to be weakly, rather than strongly, clustered, which contradicts the widespread theoretical idea that they were assessing.

    “Our analysis rules out the possibility that PBHs could be the dark matter of the universe if they have masses similar to stellar masses,” Riotto added. “In our next works, we plan to investigate the role of PBHs further, to see if they can explain other interesting observations, such as the presence of galaxies at high redshifts.”

    Science paper:
    Physical Review Letters

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    About Science X in 100 words
    Science X is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

    Mission: 12 reasons for reading daily news on Science X Organization Key editors and writers include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 4:46 pm on November 21, 2022 Permalink | Reply
    Tags: "Controversial new study claims lopsided star cluster may disprove Newton and Einstein", An uneven distribution of stars in several nearby clusters may offer evidence of "MOND" – a controversial theory of gravity that disputes Newton and rejects the existence of dark matter., , , , , Dark Matter, , Observations indicate that some clusters have many more stars sitting in the overall direction of their travel through space than trailing behind. This questions Newton's law of universal gravitation., , The Hyades star cluster, The researchers found this evidence by observing open star clusters.,   

    From The University of Bonn [Rheinische Friedrich-Wilhelms-Universität Bonn] (DE) Via “Live Science” : “Controversial new study claims lopsided star cluster may disprove Newton and Einstein” 

    From The University of Bonn [Rheinische Friedrich-Wilhelms-Universität Bonn] (DE)

    Via

    “Live Science”

    11.21.22
    Tom Metcalfe

    1
    The Hyades star cluster (pink) curls across the sky amid well-known constellations (green). The cluster is at the center of a controversial new study proposing an alternative to Newton’s theory of gravity. (Image credit: ESA/Gaia/DPAC, CC BY-SA 3.0)

    An uneven distribution of stars in several nearby clusters may offer evidence of “MOND” [below] – a controversial theory of gravity that disputes Newton and rejects the existence of dark matter.

    Astronomers observing star clusters in our galaxy have found evidence that controversially challenges Newton’s laws of gravity and could upend our understanding of the universe. The puzzling finding could support a controversial idea that does away entirely with dark matter.

    The researchers found this evidence by observing open star clusters, or loosely bound groups of up to a few hundred stars sitting within larger galaxies. Open star clusters have trails of stars, known as “tidal tails,” in front of and behind them. The researchers’ observations indicate that such clusters have many more stars sitting in the overall direction of their travel through space than trailing behind. This throws into question Newton’s law of universal gravitation, which suggests that there should be the same number of stars in both tidal tails.

    “It’s extremely significant,” astrophysicist Pavel Kroupa of the University of Bonn told Live Science. “There is a huge effect.”

    Kroupa is the lead author of a study published Oct. 26 in the MNRAS [below] that argues the observations are evidence of modified Newtonian dynamics (MOND) — an alternative theory of gravity to Newton’s widely accepted universal law of gravitation.

    This uneven distribution of stars is noticeable, but not extreme enough for any sort of dark matter — an invisible substance thought to exert a powerful gravitational pull on the universe’s visible matter — to be involved, Kroupa said.

    “This is basically a game-changer,” he said. “This destroys all the work done on galaxies and on cosmology [that] assumes dark matter and Newtonian gravity.”

    2
    In the star cluster Hyades (top), the number of stars (black) in the front tidal tail is significantly larger than those in the rear. In the computer simulation with MOND (below), a similar picture emerges. (Image credit: University of Bonn)

    Dark matter?

    Issac Newton’s universal law of gravitation, published in 1687, states that every particle in the universe attracts every other with a force proportional to their masses and inversely proportional to the square of their distance. Albert Einstein later incorporated this law into his theory of general relativity, which was published in 1915.

    But Kroupa said that at the time of both Newton and Einstein, astronomers didn’t know that galaxies even existed, and so MOND was developed to bring it up to date with observations.

    MOND, also known as Milgromian dynamics after astrophysicist Mordehai Milgrom who developed it in the early 1980s, argues that regular Newtonian dynamics don’t apply on the very large scales of galaxies and galactic clusters — although most astrophysicists think they do.

    The main consequence of MOND is that dark matter doesn’t exist — an idea that most astrophysicists dismiss, Kroupa said. “The majority of scientists completely reject Mond,” he said. “Many serious scientists don’t think Mond is serious, and so they wouldn’t consider looking at it.”
    ___________________________________________________
    “MOND”: Modified Newtonian dynamics


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


    ___________________________________________________
    Stellar clusters

    In their study, the authors report observations of five of the closest open stellar clusters to Earth, including the Hyades — a roughly spherical group of hundreds of stars that is only about 150 light-years from our sun.

    The researchers observed that stars had accumulated in the leading tidal tail in all five of the clusters, while the greatest discrepancy from regular Newtonian dynamics was seen in the Hyades cluster, where there are better measurements, Kroupa said. 

    The observed discrepancies strengthen the case for MOND, but they can’t be a result of the invisible action of dark matter.

    In the case of the Hyades, “we would have to have a clump of dark matter there like 10 million solar masses” to explain the results, he said. “But it’s just not in the data.”

    Future studies will use more precise data on the positions of stars from new space telescopes, such as the European Space Agency’s Gaia, he said.

    However, because MOND is not widely accepted by many scientists, the new study’s findings are controversial. 

    Sabine Hossenfelder, an astrophysicist at the Frankfurt Institute Advanced Studies, told Live Science in an email that she was pleased to see researchers working on gravitational simulations of MOND.

    But “as they admit the paper themselves, they are using an approximate calculation that needs to be confirmed… [and] they haven’t quantified how large the disagreement with data is,” she said. “So I think it remains to be seen how good this argument actually is.”

    Science paper:
    MNRAS

    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 University of Bonn [Rheinische Friedrich-Wilhelms-Universität Bonn] (DE) is a public research university located in Bonn, North Rhine-Westphalia, Germany. It was founded in its present form as the Rhein-Universität (English: Rhine University) on 18 October 1818 by Frederick William III, as the linear successor of the Kurkölnische Akademie Bonn (English: Academy of the Prince-elector of Cologne) which was founded in 1777. The University of Bonn offers many undergraduate and graduate programs in a range of subjects and has 544 professors. Its library holds more than five million volumes.

    As of October 2020, among its notable alumni, faculty and researchers are 11 Nobel Laureates, 4 Fields Medalists, 12 Gottfried Wilhelm Leibniz Prize winners as well as some of the most gifted minds in Natural science, e.g. August Kekulé, Heinrich Hertz and Justus von Liebig; Major philosophers, such as Friedrich Nietzsche, Karl Marx and Jürgen Habermas; Famous German poets and writers, for example Heinrich Heine, Paul Heyse and Thomas Mann; Painters, like Max Ernst; Political theorists, for instance Carl Schmitt and Otto Kirchheimer; Statesmen, viz. Konrad Adenauer and Robert Schuman; famous economists, like Walter Eucken, Ferdinand Tönnies and Joseph Schumpeter; and furthermore Prince Albert, Pope Benedict XVI and Wilhelm II.

    The University of Bonn has been conferred the title of “University of Excellence” under the German Universities Excellence Initiative.

    Research institutes

    The Franz Joseph Dölger-Institute studies the late antiquity and in particular the confrontation and interaction of Christians, Jews and Pagans in the late antiquity. The institute edits the Reallexikon für Antike und Christentum, a German language encyclopedia treating the history of early Christians in the late antiquity. The institute is named after the church historian Franz Joseph Dölger who was a professor of theology at the university from 1929 to 1940.

    The Research Institute for Discrete Mathematics focuses on discrete mathematics and its applications, in particular combinatorial optimization and the design of computer chips. The institute cooperates with IBM and Deutsche Post. Researchers of the institute optimized the chess computer IBM Deep Blue.

    The Bethe Center for Theoretical Physics “is a joint enterprise of theoretical physicists and mathematicians at various institutes of or connected with the University of Bonn. In the spirit of Hans Bethe it fosters research activities over a wide range of theoretical and mathematical physics.” Activities of the Bethe Center include short and long term visitors program, workshops on dedicated research topics, regular Bethe Seminar Series, lectures and seminars for graduate students.

    The German Reference Center for Ethics in the Life Sciences (German: Deutsches Referenzzentrum für Ethik in den Biowissenschaften) was founded in 1999 and is modeled after the National Reference Center for Bioethics Literature at Georgetown University. The center provides access to scientific information to academics and professionals in the fields of life science and is the only of its kind in Germany.

    After the German Government’s decision in 1991 to move the capital of Germany from Bonn to Berlin, the city of Bonn received generous compensation from the Federal Government. This led to the foundation of three research institutes in 1995, of which two are affiliated with the university:

    The Center for European Integration Studies (German: Zentrum für Europäische Integrationsforschung) studies the legal, economic and social implications of the European integration process. The institute offers several graduate programs and organizes summer schools for students.

    The Center for Development Research (German: Zentrum für Entwicklungsforschung) studies global development from an interdisciplinary perspective and offers a doctoral program in international development.

    The Center of Advanced European Studies and Research (CAESAR) is an interdisciplinary applied research institute. Research is conducted in the fields of nanotechnology, biotechnology and medical technology. The institute is a private foundation, but collaborates closely with the university.

    The Institute for the Study of Labor (German: Forschungsinstitut zur Zukunft der Arbeit) is a private research institute that is funded by Deutsche Post. The institute concentrates on research on labor economics, but is also offering policy advise on labor market issues. The institute also awards the annual IZA Prize in Labor Economics. The department of economics of the University of Bonn and the institute closely cooperate.

    The MPG Institute for Mathematics [MPG Institut für Mathematik](DE) is part of the MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] (DE), a network of scientific research institutes in Germany. The institute was founded in 1980 by Friedrich Hirzebruch.

    The MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE) was founded in 1966 as an institute of the MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] (DE). It operates the radio telescope in Effelsberg.

    Effelsberg Radio Telescope- a radio telescope in the Ahr Hills (part of the Eifel) in Bad Münstereifel(DE)
    The MPG Institute for Research on Collective Goods [MPG Institut zur Erforschung von Gemeinschaftsgütern)(DE) started as a research group in 1997 and was founded as an institute of the Max-Planck-Gesellschaft in 2003. The institute studies collective goods from a legal and economic perspective.

    The Center for Economics and Neuroscience founded in 2009 by Christian Elger, Gottfried Wilhelm Leibniz Prize winner Armin Falk, Martin Reuter and Bernd Weber, provides an international platform for interdisciplinary work in neuroeconomics. It includes the Laboratory for Experimental Economics that can carry out computer-based behavioral experiments with up to 24 participants simultaneously, two magnetic resonance imaging (MRI) scanners for interactive behavioral experiments and functional imaging, as well as a biomolecular laboratory for genotyping different polymorphisms.

    Research

    University of Bonn researchers made fundamental contributions in the sciences and the humanities. In physics researchers developed the quadrupole ion trap and the Geissler tube, discovered radio waves, were instrumental in describing cathode rays and developed the variable star designation. In chemistry researchers made significant contributions to the understanding of alicyclic compounds and Benzene. In material science researchers have been instrumental in describing the lotus effect. In mathematics University of Bonn faculty made fundamental contributions to modern topology and algebraic geometry. The Hirzebruch–Riemann–Roch theorem, Lipschitz continuity, the Petri net, the Schönhage–Strassen algorithm, Faltings’s theorem and the Toeplitz matrix are all named after University of Bonn mathematicians. University of Bonn economists made fundamental contributions to game theory and experimental economics. Famous thinkers that were faculty at the University of Bonn include the poet August Wilhelm Schlegel, the historian Barthold Georg Niebuhr, the theologians Karl Barth and Joseph Ratzinger and the poet Ernst Moritz Arndt.

    The university has nine collaborative research centres and five research units funded by the German Science Foundation and attracts more than 75 million Euros in external research funding annually.

    The Excellence Initiative of the German government in 2006 resulted in the foundation of the Hausdorff Center for Mathematics as one of the seventeen national Clusters of Excellence that were part of the initiative and the expansion of the already existing Bonn Graduate School of Economics (BGSE). The Excellence Initiative also resulted in the founding of the Bonn-Cologne Graduate School of Physics and Astronomy (an honors Masters and PhD program, jointly with the University of Cologne). Bethe Center for Theoretical Physics was founded in the November 2008, to foster closer interaction between mathematicians and theoretical physicists at Bonn. The center also arranges for regular visitors and seminars (on topics including String theory, Nuclear physics, Condensed matter etc.).

     
  • richardmitnick 9:11 am on November 16, 2022 Permalink | Reply
    Tags: "Axion Miniclusters Might Be Microlenses", , Asteroid-sized clumps of a dark matter candidate known as an axion could be detectable in a gravitational-microlensing survey., Dark Matter,   

    From “Physics” : “Axion Miniclusters Might Be Microlenses” 

    About Physics

    From “Physics”

    11.15.22
    Rachel Berkowitz

    Asteroid-sized clumps of a dark matter candidate known as an axion could be detectable in a gravitational-microlensing survey.

    1
    Credit: D. Ellis/Georg August University of Göttingen.

    The axion, a leading dark matter candidate, is hypothesized to make up the dark matter halos thought to surround galaxies.

    In certain models, axions coalesce into “miniclusters”—dark matter clumps with masses of around 1019 kg. David Ellis at the Georg August University of Göttingen, Germany, and his colleagues now show that these miniclusters can act as gravitational lenses that magnify light from background sources [1]. They find a range of axion-particle masses for which the miniclusters might be observable in gravitational-lensing surveys.

    The axion model predicts that axions formed in the early Universe. When the Universe cools below a certain temperature, topological defects form in the vacuum of space. If those defects originated during the radiation-dominated phase of the early Universe, their subsequent decay could have led to large, excess-density patches called minicluster seeds. These seeds would then have collapsed under gravity and merged to form axion miniclusters, possibly with Bose-Einstein condensates of axions—called axion stars—at their centers. But the properties of these miniclusters, such as their mass and density profile, remain uncertain and difficult to predict.

    Using cosmological simulations, Ellis and his colleagues followed the evolution of the densest minicluster seeds over the Universe’s history. They found that the late-time minicluster density distribution fits the profile predicted for the hypothesized dark matter halos. They also found that if the axion mass is between 0.2 and 3 meV—a range supported by studies that predict the axion-particle mass using astronomical observations—enough of these miniclusters may be sufficiently dense to give rise to detectable gravitational-microlensing events. Models show that such microlensing should be hindered by the presence of axion stars, so to increase the confidence of their prediction, the researchers say that higher-resolution simulations are needed to determine the inner structure of the densest miniclusters.

    References:

    [1.] D. Ellis et al., “Structure of axion miniclusters,” Phys. Rev. D 106, 103514 (2022).

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments.

     
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