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  • richardmitnick 5:06 pm on February 6, 2020 Permalink | Reply
    Tags: , , , , Dark Energy Camera, , , South Pole Telescope,   

    From University of Chicago: “Leftover Big Bang light helps calculate how massive faraway galaxies are” 

    U Chicago bloc

    From University of Chicago

    Feb 6, 2020
    Catherine N. Steffel , FNAL

    The South Pole Telescope provided key data for scientists to create a new method to weigh galaxy clusters. Photo by Daniel Michalik

    Fermilab, UChicago scientists tap South Pole Telescope data to shed light on universe.

    A team of scientists have demonstrated how to “weigh” galaxy clusters using light from the earliest moments of the universe—a new method that could help shed light on dark matter, dark energy and other mysteries of the cosmos, such as how the universe formed.

    The new method calculates the bending of light around galaxy clusters using the orientation of light from shortly after the Big Bang—data taken by the South Pole Telescope and the Dark Energy Camera.

    Dark Energy Survey

    Dark Energy Camera [DECam], built at FNAL

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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

    “Gravitational lensing,” a phenomenon in which light distorts as it’s affected by the gravity of big objects like galaxies, can function as a kind of magnifying glass.

    Gravitational Lensing NASA/ESA

    It’s helped scientists discover key information about the universe—but it’s always been done by looking for the smearing of light around distant objects like stars.

    In a study published in Physical Review Letters, Fermilab and University of Chicago scientist Brad Benson and colleagues use a different method to calculate the masses of distant galaxies: the polarization, or orientation, of the light left over from the moments after the Big Bang.

    “Making this estimate is important because most of the mass of galaxy clusters isn’t even visible—it’s dark matter, which does not emit light but interacts through gravity and makes up about 85% of the matter in our universe,” said Benson, an assistant professor in the Department of Astronomy and Astrophysics. “Since photons from the cosmic microwave background have literally traveled across the entire observable universe, this method has the potential to more accurately measure the dark matter mass in the most distant galaxy clusters.”

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

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

    Coma cluster via NASA/ESA Hubble

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

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

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

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

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

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

    Dark Matter Research

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

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

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

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

    Dark Matter Particle Explorer China

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

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

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

    Clues from the beginning of time

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

    Over the next 400,000 years, the universe expanded and cooled to about 3,000 degrees Celsius. At these temperatures, electrons and protons combined into hydrogen atoms and released photons in the process. This light, called the cosmic microwave background, or CMB, has been traveling through space ever since—a sort of “time machine” carrying information from the early universe.

    At the Amundsen-Scott South Pole Station, support staff and scientists, nicknamed “beakers,” work around the clock to manage the South Pole Telescope.

    South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including the University of Chicago, the University of California, Berkeley, Case Western Reserve University, Harvard/Smithsonian Astrophysical Observatory, the University of Colorado Boulder, McGill University, The University of Illinois at Urbana-Champaign, University of California, Davis, Ludwig Maximilian University of Munich, Argonne National Laboratory, and the National Institute for Standards and Technology. It is funded by the National Science Foundation.

    It’s not easy work; it is located at the southernmost place on Earth, where the average temperature is minus 47 degrees Celsius and the sun rises and sets only once a year. But the South Pole Telescope needs this harsh environment to carry out its scientific work.

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

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

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

    “If you look through the bottom of a wine glass base at a flame, you can see a ring of light. That’s like the effect we would see from a strong gravitational lens,” Benson said. “We are seeing a similar effect here, except the distortion is much weaker and the CMB light is spread out over a much larger area on the sky.”

    An assist from the Dark Energy Camera

    To find the maximum number of clusters, the scientists cross-referenced data from the Dark Energy Survey, a multi-year survey of the sky that captured the locations of more than 17,000 galaxy clusters in the universe.

    Then they could put these locations into a computer program that searched for evidence of gravitational lensing by the clusters in the polarization of the CMB. Once evidence was found, they could calculate the masses of the galaxy clusters themselves using their new mathematical estimator.

    Though the idea had been proposed, no one had yet demonstrated the method on actual data.

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

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

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

    See the full article here .


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    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics, establishing revolutionary theories of economics, and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations with our national and affiliated laboratories: Argonne National Laboratory, Fermi National Accelerator Laboratory, and the Marine Biological Laboratory in Woods Hole, Massachusetts.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts.

  • richardmitnick 7:28 am on February 7, 2018 Permalink | Reply
    Tags: , , , , , South Pole Telescope,   

    From CfA: “Massive Galaxies in the Early Universe” 

    Harvard Smithsonian Center for Astrophysics

    Center For Astrophysics

    February 2, 2018

    The South Pole Telescope (SPT) is a 10-meter-diameter telescope in the Antarctic that has been operating at millimeter- and submillimeter-waves for a decade; the CfA is an institutional member of the collaboration.

    South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including the University of Chicago, the University of California, Berkeley, Case Western Reserve University, Harvard/Smithsonian Astrophysical Observatory, the University of Colorado Boulder, McGill University, The University of Illinois at Urbana-Champaign, University of California, Davis, Ludwig Maximilian University of Munich, Argonne National Laboratory, and the National Institute for Standards and Technology. It is funded by the National Science Foundation.

    For the past six years it has been surveying the sky in a search for galaxies in the first few billion years of cosmic history; they are thought to be preferentially detectable at these wavelengths because their dust has been heated by the ultraviolet light of young stars. One of SPT discoveries, the galaxy SPT0311–58, has upon further investigation turned out to date from an epoch a mere 780 million years after the big bang. It is the most distant known case of this postulated but previously undetected population of optically dim but infrared luminous clusters.

    CfA astronomers Chris Hayward, Matt Ashby and Tony Stark are members of the SPT team that made the discovery and then followed up with the Spitzer Space Telescope, the ALMA array, the Hubble Space Telescope, and the Gemini optical/infrared telescope.

    NASA/Spitzer Infrared Telescope

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    NASA/ESA Hubble Telescope

    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

    The scientists were able to determine the cluster’s distance and epoch from the redshift of its spectral features, including a line of ionized carbon, and to characterize the overall emission properties across a wider range of wavelengths. The Spitzer and Hubble images of the source revealed the presence of a foreground galaxy that is acting as a gravitational lens to magnify SPT0311-58 and thus greatly facilitated its detection. The ALMA measurements at high spatial resolution found that the original source is actually two galaxies less than twenty-five thousand light-years apart. The implication is that these two galaxies are in the midst of colliding.

    The masses of the two galaxies are nearly one hundred billion and ten billion solar masses, respectively. The larger one is more massive than any other known galaxy at this early time in cosmic evolution, a period during which many galaxies are thought to be just forming, and is very bright, making new stars at a rate of about 2900 solar masses per year (thousands of times faster than the Milky Way). Although current models of cosmic evolution do not preclude such giant systems from existing at such early times, the observation does push the models to its limits. The results also imply that there should be a dark-matter halo present with more than 400 billion solar masses, among the rarest dark-matter haloes that should exist in the early universe.


    Galaxy Growth in a Massive Halo in the First Billion Years of Cosmic History, D. P. Marrone, J. S. Spilker, C. C. Hayward, J. D. Vieira, M. Aravena, M. L. N. Ashby, M. B. Bayliss, M. B’ethermin, M. Brodwin, M. S. Bothwell, J. E. Carlstrom, S. C. Chapman, Chian-Chou Chen, T. M. Crawford;, D. J. M. Cunningham, C. De Breuck, C. D. Fassnacht, A. H. Gonzalez, T. R. Greve, Y. D. Hezaveh, K. Lacaille, K. C. Litke, S. Lower, J. Ma, M. Malkan, T. B. Miller, W. R. Morningstar, E. J. Murphy, D. Narayanan, K. A. Phadke, K. M. Rotermund, J. Sreevani, B. Stalder, A. A. Stark, M. L. Strandet, M. Tang, & A. Weiß, Nature, 553, 51, 2018.

    a, Emission in the 157.74-μm fine-structure line of ionized carbon ([C ii]) as measured at 240.57 GHz with ALMA, integrated over 1,500 km s−1 of velocity, is shown with the colour scale. The range in flux per synthesized beam (the 0.25″ × 0.30″ beam is shown in the lower left) is provided at right. The rest-frame 160-μm continuum emission that was measured simultaneously is overlaid, with contours at 8, 16, 32 and 64 times the noise level of 34 μJy per beam. SPT0311−58 E and SPT0311−58 W are labelled. b, The continuum-subtracted, source-integrated [C ii] (red) and [O iii] (blue) spectra. The upper spectra are as observed (‘apparent’) with no correction for lensing, whereas the lensing-corrected (‘intrinsic’) [C ii] spectrum is shown at the bottom. SPT0311−58 E and SPT0311−58 W separate almost completely at a velocity of 500 km s−1. c, The source-plane structure after removing the effect of gravitational lensing. The image is coloured according to the flux-weighted mean velocity, showing that the two objects are physically associated but separated by roughly 700 km s−1 in velocity and 8 kpc (projected) in space. The reconstructed 160-μm continuum emission is shown as contours. The scale bar represents the angular size of 5 kpc in the source plane. d, The line-to-continuum ratio at the 158-μm wavelength of [C ii], normalized to the map peak. The [C ii] emission from SPT0311−58 E is much brighter relative to its continuum than for SPT0311−58 W. e, Velocity-integrated emission in the 88.36-μm fine-structure line of doubly ionized oxygen ([O iii]) as measured at 429.49 GHz with ALMA (colour scale). The data have an intrinsic angular resolution of 0.2″ × 0.3″, but have been tapered to 0.5″ owing to the lower signal-to-noise ratio of these data. f, The luminosity ratio between the [O iii] and [C ii] lines. As for the [C ii] line-to-continuum ratio, a large disparity is seen between SPT0311−58 E and SPT0311−58 W. The sky coordinates and contours for rest-frame 160-μm continuum emission in d–f are the same as in a.

    See the full article here .

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    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

  • richardmitnick 8:25 am on May 25, 2017 Permalink | Reply
    Tags: , , , , , , , South Pole Telescope   

    From Nautilus: “The Origin of the Universe” 



    April 2017
    John Carlstrom

    The current South Pole telescope measuring small variations in the cosmic microwave background radiation that permeates the universe. Multiple telescopes with upgraded detectors could unlock additional secrets about the origins of the universe. Jason Gallicchio

    Measuring tiny variations in the cosmic microwave background will enable major discoveries about the origin of the universe.

    CMB per ESA/Planck


    How is it possible to know in detail about things that happened nearly 14 billion years ago? The answer, remarkably, could come from new measurements of the cosmic microwave radiation that today permeates all space, but which was emitted shortly after the universe was formed.

    Previous measurements of the microwave background showed that the early universe was remarkably uniform, but not perfectly so: There are small variations in the intensity (or temperature) and polarization of the background radiation. These faint patterns show close agreement with predictions from what is now the standard theoretical model of how the universe began. That model describes an extremely energetic event—the Big Bang—followed within a tiny fraction of a second by a period of very accelerated expansion of the universe called cosmic inflation.

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

    HPHS Owls

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

    Alan Guth’s notes. http://www.bestchinanews.com/Explore/4730.html

    During this expansion, small quantum fluctuations were stretched to astrophysical scales, becoming the seeds that gave rise to the galaxies and other large-scale structures of the universe visible today.

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

    After the cosmic inflation ended, the expansion began to slow and the primordial plasma of radiation and high-energy sub-atomic particles began to cool. Within a few hundred thousand years, the plasma had cooled sufficiently for atoms to form, for the universe to become transparent to light, and for the first light to be released. That first light has since been shifted—its wavelengths stretched 1,000-fold into the microwave spectrum by the continuing expansion of the universe—and is what we now measure as the microwave background [see above].

    Inflationary Universe. NASA/WMAP

    Recently the development of new superconducting detectors and more powerful telescopes are providing the tools to conduct an even more detailed study of the microwave background. And the payoff could be immense, including additional confirmation that cosmic inflation actually occurred, when it occurred, and how energetic it was, in addition to providing new insights into the quantum nature of gravity. Specifically the new research we propose can address a wide range of fundamental questions:

    1. The accelerated expansion of the universe in the first fraction of a second of its existence, as described by the inflation model, would have created a sea of gravitational waves. These distortions in spacetime would in turn would have left a distinct pattern in the polarization of the microwave background. Detecting that pattern would thus provide a key test of the inflation model, because the level of the polarization links directly to the time of inflation and its energy scale.
    2. Investigating the cosmic gravitational wave background would build on the stunning recent discovery of gravity waves, apparently from colliding black holes, helping to further the new field of gravitational wave astronomy.
    3. These investigations would provide a valuable window on physics at unimaginably high energy scales, a trillion times more energetic than the reach of the most powerful Earth-based accelerators.
    4. The cosmic microwave background provides a backlight on all structure in the universe. Its precise measurement will illuminate the evolution of the universe to the present day, allowing unprecedented insights and constraints on its still mysterious contents and the laws that govern them.

    The origin of the universe was a fantastic event. To gain an understanding of that beginning as an inconceivably small speck of spacetime and its subsequent evolution is central to unraveling continuing mysteries such as dark matter and dark energy. It can shed light on how the two great theories of general relativity and quantum mechanics relate to each other. And it can help us gain a clearer perspective on our human place within the universe. That is the opportunity that a new generation of telescopes and detectors can unlock.

    How to Measure Variations in the Microwave Background with Unparalleled Precision

    Figure 1Ultra-sensitive superconducting bolometer detectors manufactured with thin-film techniques. The project proposes to deploy 500,000 such detectors. Chrystian Posada Arbelaez.

    The time for the next generation cosmic microwave background experiment is now. Transformational improvements have been made in both the sensitivity of microwave detectors and the ability to manufacture them in large numbers at low cost. The advance stems from the development of ultra-sensitive superconducting detectors called bolometers. These devices (Figure 1) essentially eliminate thermal noise by operating at a temperature close to absolute zero, but also are designed to make sophisticated use of electrothermal feedback—adjusting the current to the detectors when incoming radiation deposits energy, so as to keep the detector at its critical superconducting transition temperature under all operating conditions. The sensitivity of these detectors is limited only by the noise of the incoming signal—they generate an insignificant amount of noise of their own.

    Equally important are the production advances. These new ultra-sensitive detectors are manufactured with thin film techniques adapted from Silicon Valley—although using exotic superconducting materials—so that they can be rapidly and uniformly produced at greatly reduced cost. That’s important, because the proposed project needs to deploy about 500,000 detectors in all—something that would not be possible with hand-assembled devices as in the past. Moreover, the manufacturing techniques allow these sophisticated detectors to automatically filter the incoming signals for the desired wavelength sensitivity.

    Figure 2The current focal plane on the South Pole Telescope with seven wafers of detectors plus hand-assembled individual detectors. A single detector wafer of the advanced design proposed here would provide more sensitivity and frequency coverage than this entire focal plane; the project would deploy several hundred such wafers across 10 or more telescopes. Jason Henning.

    To deploy the detectors, new telescopes are needed that have a wide enough focal plane to accommodate a large number of detectors—about 10,000 per telescope to capture enough incoming photons and see a wide enough area of the sky (Figure 2). They need to be placed at high altitude, exceedingly dry locations, so as to minimize the water vapor in the atmosphere that interferes with the incoming photons. The plan is to build on the two sites already established for ongoing background observations, the high Antarctic plateau at the geographic South Pole, and the high Atacama plateau in Chile. Discussions are underway with the Chinese about developing a site in Tibet; Greenland is also under consideration. In all, about 10 specialized telescopes will be needed, and will need to operate for roughly 5 years to accomplish the scientific goals described above. Equally important, the science teams that have come together to do this project will need significant upgrades to their fabrication and testing capabilities.

    The resources needed to accomplish this project are estimated at $100 million over 10 years, in addition to continuation of current federal funding. The technology is already proven and the upgrade path understood. Equally important, a cadre of young, enthusiastic, and well-trained scientists are eager to move forward. Unfortunately, constraints on the federal funding situation are already putting enormous stress on the ability of existing teams just to continue, and the expanded resources to accomplish the objectives described above are not available. This is thus an extraordinary opportunity for private philanthropy—an opportunity to “see” back in time to the very beginning of the universe and to understand the phenomena that shaped our world.

    See the full article here .

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  • richardmitnick 12:04 pm on January 28, 2016 Permalink | Reply
    Tags: , , , , New camera, South Pole Telescope,   

    From U Chicago: “South Pole’s next generation of discovery” 

    U Chicago bloc

    University of Chicago

    January 26, 2016
    Carla Reiter

    UChicago, Argonne, and Fermilab collaborate on telescope’s new ultra-sensitive camera

    South Pole Telescope
    South Pole Telescope

    Later this year, during what passes for summer in Antarctica, a group of Chicago scientists will arrive at the Amundsen–Scott South Pole research station to install a new and enhanced instrument designed to plumb the earliest history of the cosmos.

    It will have taken the combined efforts of scientists, engineers, instrument builders, and computer experts at UChicago, Argonne National Laboratory, Fermilab, as well as institutions across the world that participate in the South Pole Telescope collaboration.

    “It’s a really technically challenging scientific project,” says Fermilab Director Nigel Lockyer, “and you couldn’t do it without the national labs’ expertise and enabling technical infrastructure.”

    Led by John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy and Astrophysics, the South Pole Telescope is a global collaboration of more than a dozen institutions. It probes the cosmic microwave background [CMB]—the radiation that remains from the Big Bang—for insight into how the universe has evolved and the processes and particles that have participated in that evolution.

    CMB Planck ESA
    CMB per ESA/Planck

    ESA Planck

    “The physics of the early universe was imprinted into patterns in the cosmic microwave background that we can measure,” says Clarence Chang, who heads Argonne’s part of the project—the design and fabrication of the detectors. “But it is very faint, so we need a very sensitive camera.”

    A new ultra-sensitive camera is both the heart of the telescope and the focal point of the collaboration between Argonne, Fermilab, and Chicago.

    “UChicago is the scientific lead,” says Bradford Benson, an associate scientist and Wilson Fellow at Fermilab who directs the design of the camera and its integration with cryogenics, detectors, and electronics. “Fermilab provides expertise and resources at the integration level: How do we build this thing, package it, and operate it for many years? And Argonne has micro-fabrication resources that aren’t available elsewhere.”

    The South Pole Telescope project is one of multiple collaborations among UChicago, Argonne, and Fermilab scientists. Others include experiments that examine the nature of neutrinos; as well as those including future accelerator science and technology.

    Microwave-sensitive camera

    South Pole Telescope SPT-3G Camera
    New 3g camera

    The camera on the South Pole Telescope is made of an array of superconducting detectors that are sensitive to the frequencies associated with the CMB. Each requires depositing ultra-thin superconducting materials with dimensions as small as about 10 x 50 microns (50 microns is the approximate width of a human hair). These delicate detectors are built at Argonne, using the state-of-the-art facilities at the Center for Nanoscale Materials and materials developed in the lab’s Materials Sciences Division. The new focal plane uses integrated arrays of detectors on 150 mm silicon wafers, with ten of these modules making up the heart of the camera.

    “They’re actually detecting the photons from 14 billion years ago,” Chang says. “They heat up the detectors a tiny bit, and then we measure that heat.”

    The finished detector array modules go to Fermilab, where they are packaged and connected with the electronics for testing in the lab’s Silicon Detector Facility—a thornier task than it sounds. Each module requires thousands of hair-like wires to be connected individually to cable. Fermilab has specialized wire bonders that are accomplish this task, says Benson.

    Then the assembly goes to the University of Chicago, where it is tested at a quarter of a degree above absolute zero—the temperature required for the superconducting detectors to be able to sense the tiny amount of heat from the incoming photons. The test results are then fed back to Argonne for adjustments to be made for the fabrication of the next modules. Ultimately everything winds up back at UChicago, to be integrated into a 2,000-pound camera to ship to the South Pole.

    The new camera will have 16,000 detectors—a major upgrade from the 1,600-detector camera currently on the telescope. The scientists will use the increased sensitivity to search for the signature of primordial gravitational waves that an inflationary universe would have generated early in its history. A detection would probe physics at the enormous energies that existed when the universe was only a fraction of a second old—complementary to the studies at the energy scales of the Large Hadron Collider.

    The new camera also will enable them to obtain precision measurements that will help determine the mass of neutrinos, so-called ghost particles that were created in huge numbers shortly after the university began and which contribute significantly to its evolution.

    Instrumentation mass production

    Making 16,000 of anything isn’t something universities typically do.

    “People are often trying to make one device, understand the physics of it, and publish a paper on it,” says Benson. “We’re trying to build these instruments that are on a much larger scale, and they need to be mass produced. There’s not much of a technical staff or infrastructure at a university to maintain something like that on a five or 10-year time scale. Argonne has built up that expertise. And we can plug into that.”

    Chang, Benson, and Carlstrom have collaborated on the SPT project for more than a decade. They have worked to create as seamless a process as possible so that scientists, postdocs, and students can go back and forth between groups with no bureaucratic barriers. Both Chang and Benson have part-time appointments at the University, which helps.

    “The collaboration lets us do more than what we could ever do otherwise,” says Chang. “We’ve cultivated the ability to have a single group of 20 or 30 people. You’ll never have a group in a university or at either of the labs that is that big. There’s a critical mass, intellectually, that emerges from that. I think that’s the biggest thing that we get out of this. And that’s something that’s hard to find elsewhere, either at other labs or at other universities.”

    Although the new telescope isn’t yet installed at the South Pole, the project partners are already looking ahead to the next, more sensitive telescope.

    “A project the size of the fourth-generation South Pole Telescope requires grand collaborations,” said Argonne Director Peter Littlewood. “In order to build, install, and operate an instrument with half a million sensors, we are investing in a multi-institution combination of strong project management and state-of-the-art physical infrastructure to create something truly extraordinary for science.”

    See the full article here .

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  • richardmitnick 9:24 am on May 29, 2015 Permalink | Reply
    Tags: , , , , South Pole Telescope   

    From FNAL- “Frontier Science Result: South Pole Telescope Gravitational lensing of the cosmic microwave background by galaxy clusters” 

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    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    May 29, 2015
    Scott Dodelson

    The left panel shows a simulated map of an unlensed cosmic microwave background. The center panel shows the same map if a large galaxy cluster were along the line of sight. Note that the scale on these two panels goes to 100 microKelvin. The right panel shows the difference between the first two panels. The scale is now down to 10 microKelvin. (Plots are in units of arcminutes.) Image: Antony Lewis and Lindsay King, Institute of Astronomy

    The photons that make up the cosmic microwave background (CMB) have traversed the universe almost freely for 13.8 billion years, thereby carrying information about the state of the universe when it was only 380,000 years old.

    Cosmic Background Radiation Planck
    CMB per ESA/Planck

    ESA Planck

    “Almost freely” refers to two ways that these photons are disturbed along their long journeys: They are sometimes scattered by hot electrons and they are deflected by deep gravitational wells.

    It is this latter deflection, called gravitational lensing, that offers immense promise as a tool to weigh massive objects such as galaxy clusters. Clusters are very important because their abundance offers insight into why the universe is currently accelerating. Extracting this insight, though, requires careful estimates of the masses of clusters. There are currently several techniques in play: X-ray emission, galaxy counts in the clusters, distortions of the shapes of background galaxies and the signal imprinted on the CMB by hot electrons in clusters.

    Lensing of the CMB provides a new way to measure cluster masses, one that has just been demonstrated. A simulated signal from one cluster is shown above. Each panel represents about 35 square arcminutes, about 20 times smaller than the moon, so a CMB experiment must have excellent resolution to see the effect. Cluster lensing is the difference between the left and center panels, shown in the right panel. The signal is roughly several microKelvin, much smaller than the typical hot and cold spots that have made the CMB famous. So the resolution must be coupled with exquisite sensitivity.

    Large ground-based telescopes such as the 10-meter South Pole Telescope [SPT] are beginning to attain this dual capability.

    South Pole Telescope

    The noise levels are still too high to measure lensing by a single cluster, so the SPT team performed a likelihood analysis using 513 clusters, detected over three years of the telescope’s operation, to measure the weighted mass. The result was a 3-sigma measurement of the lensing of the CMB, with the mass consistent with those obtained with other methods. A paper on this result has recently been accepted for publication in The Astrophysical Journal.

    The team is now optimistic that this effect will lead to competitive constraints on cluster masses with upcoming surveys, such as SPT-3G and CMB-S4.

    See the full article here.

    Please help promote STEM in your local schools.

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    Fermilab Campus

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

  • richardmitnick 11:23 am on March 20, 2015 Permalink | Reply
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    From FNAL: “Expanding the cosmic search” 

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    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Friday, March 20, 2015
    Diana Kwon

    South Pole Telescope

    Down at the South Pole, where temperatures drop below negative 100 degrees Fahrenheit and darkness blankets the land for six months at a time, the South Pole Telescope (SPT) searches the skies for answers to the mysteries of our universe.

    This mighty scavenger is about to get a major upgrade — a new camera that will help scientists further understand neutrinos, the ghost-like particles without electric charge that rarely interact with matter.

    The 10-meter SPT is the largest telescope ever to make its way to the South Pole. It stands atop a two-mile thick plateau of ice, mapping the cosmic microwave background (CMB), the light left over from the big bang. Astrophysicists use these observations to understand the composition and evolution of the universe, all the way back to the first fraction of a second after the big bang, when scientists believe the universe quickly expanded during a period called inflation.

    Cosmic Microwave Background  Planck
    CMB per ESA/Planck

    ESA Planck

    One of the goals of the SPT is to determine the masses of the neutrinos, which were produced in great abundance soon after the big bang. Though nearly massless, because neutrinos exist in huge numbers, they contribute to the total mass of the universe and affect its expansion. By mapping out the mass density of the universe through measurements of CMB lensing, the bending of light caused by immense objects such as large galaxies, astrophysicists are trying to determine the masses of these elusive particles.

    To conduct these extremely precise measurements, scientists are installing a bigger, more sensitive camera on the telescope. This new camera, SPT-3G, will be four times heavier and have a factor of about 10 more detectors than the current camera. Its higher level of sensitivity will allow researchers to make extremely precise measurements of the CMB that will hopefully make it possible to cosmologically detect neutrino mass.

    South Pole Telescope SPT-3G Camera

    “In the next several years, we should be able to get to the sensitivity level where we can measure the number of neutrinos and derive their mass, which will tell us how they contribute to the overall density of the universe,” explained Bradford Benson, the head of the CMB Group at Fermilab. “This measurement will also enable even more sensitive constraints on inflation and has the potential to measure the energy scale of the associated physics that caused it.”

    A wafer of detectors for the SPT-3G camera undergoes inspection at Fermilab. Photo: Bradford Benson, University of Chicago and Fermilab

    This photo shows an up-close look at a single SPT-3G detector. Photo: Volodymyr Yefremenko, Argonne National Laboratory

    SPT-3G is being completed by a collaboration of scientists spanning the DOE national laboratories, including Fermilab and Argonne, and universities including the University of Chicago and University of California, Berkeley. The national laboratories provide the resources needed for the bigger camera and larger detector array while the universities bring years of expertise in CMB research.

    “The national labs are getting involved because we need to scale up our infrastructure to support the big experiments the field needs for the next generation of science goals,” Benson said. Fermilab’s main role is the initial construction and assembly of the camera, as well as its integration with the detectors. This upgrade is being supported mainly by the Department of Energy and the National Science Foundation, which also supports the operations of the experiment at the South Pole.

    Once the camera is complete, scientists will bring it to the South Pole, where conditions are optimal for these experiments. The extreme cold prevents the air from holding much water vapor, which can absorb microwave signals, and the sun, another source of microwaves, does not rise between March and September.

    The South Pole is accessible only for about three months during the year, starting in November. This fall, about 20 to 30 scientists will head down to the South Pole to assemble the camera on the telescope and make sure everything works before leaving in mid-February. Once installed, scientists will use it to observe the sky over four years.

    “For every project I’ve worked on, it’s that beginning — when everyone is so excited not knowing what we’re going to find, then seeing things you’ve been dreaming about start to show up on the computer screen in front of you — that I find really exciting,” said University of Chicago’s John Carlstrom, the principal investigator for the SPT-3G project.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

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

  • richardmitnick 11:18 am on July 11, 2014 Permalink | Reply
    Tags: , , , , , , South Pole Telescope   

    From BBC- “Cosmic inflation: BICEP2 and Planck to share data” 


    3 July 2014
    Jonathan Amos

    The BICEP2 telescope studied a small patch of sky in detail above the South Pole

    Scientists on rival projects looking for evidence that the early Universe underwent a super-expansion are in discussion about working together.

    The negotiations between the US-led BICEP2 group and Europe’s Planck Collaboration are at an early stage.

    BICEP2 announced in March that its South Pole telescope had found good evidence for “cosmic inflation“.

    South Pole Telescope
    South Pole Telescope

    Cosmic Background Radiation Planck
    CMB from Planck

    But to be sure, it needs the best data on factors that confound its research – data that Planck has been compiling.

    If the two teams come to an arrangement, it is more likely they will hammer down the uncertainties.

    “We’re still discussing the details but the idea is to exchange data between the two teams and eventually come out with a joint paper,” Dr Jan Tauber, the project scientist on the European Space Agency’s Planck satellite, told BBC News.

    This paper, hopefully, would be published towards the end of the year, he added.

    Foreground dust per Planck

    The question of whether the BICEP2 team did, or did not, identify a signal on the sky for inflation has gripped the science world for weeks.

    The group used an extremely sensitive detector in its Antarctic telescope to study light coming to Earth from the very edge of the observable Universe – the famous Cosmic Microwave Background (CMB) radiation.
    Planck artist impression The Planck satellite was launched in 2009 to map the Cosmic Microwave Background

    BICEP2 looked for swirls in the polarisation of the light.

    This pattern in the CMB’s directional quality is a fundamental prediction of inflation – the idea that there was an ultra-rapid expansion of space just fractions of a second after the Big Bang.

    The twists, known as B-modes, are an imprint of the waves of gravitational energy that would have accompanied the violent growth spurt.

    But this primordial signal – if it exists – is expected to be extremely delicate, and a number of independent scientists have expressed doubts about the American team’s finding. And the BICEP2 researchers themselves lowered their confidence in the detection when they formally published their work in a Physical Review Letters paper last month.

    At issue is the role played by foreground dust in our galaxy.

    Nearby spinning grains can produce an identical polarisation pattern, and this effect must be removed to get an unambiguous view of the primordial, background signal.

    The BICEP2 team used every piece of dust information it could source on the part of the sky it was observing above Antarctica.

    What it lacked, however, was access to the dust data being compiled by the Planck space telescope, which has mapped the microwave sky at many more frequencies than BICEP2.

    This allows it to more easily characterise the dust and discern its confounding effects.
    Dust Planck released dust information close to the galactic plane in May

    In May, the Planck Collaboration published dust polarisation information gathered close to the galaxy’s centre – where the grains are most abundant.

    In a few weeks’ time, the Planck team plans to release further information detailing galactic dust in high latitude regions, including the narrow patch of the southern sky examined by BICEP2.

    And then, in late October, the Planck Collaboration is expected to say something about whether it can detect primordial B-modes.

    As Dr Tauber explained, Planck’s approach to the problem is a different one to BICEP2’s.

    “Planck’s constraints on primordial B-modes will come from looking at the whole sky with relatively low sensitivity as compared to BICEP2,” he said.

    “But because we can look at the whole sky, it makes up for some of that [lower sensitivity] at least. On the other hand, we have to deal with the foregrounds – we can’t ignore them at all.

    “At the same time, we will work together with BICEP2 so that we can contribute our data to improve the overall assessment of foregrounds and the Cosmic Microwave Background.

    “We hope to start working with them very soon, and if all goes well then we can maybe publish in the same timeframe as our main result [at the end of October].”

    See the full article here.

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