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  • richardmitnick 1:25 pm on April 12, 2018 Permalink | Reply
    Tags: , , , , DES - Dark Energy Survey,   

    From NOAO: “Sixth Data Release of the DESI Legacy Surveys: More Stars & Galaxies, More Science Opportunities” 

    NOAO Banner

    1
    Figure 1: A selection of image cutouts from the DR5 and DR6 Legacy Surveys data illustrating the variety of astronomical objects covered by the surveys and highlighting the capability of the surveys to image low surface brightness features. The horizontal white bar in the lower-right corner of each image corresponds to one arcminute. No image credit.

    The DESI Legacy Surveys are a collection of three imaging surveys jointly mapping approximately 14,000 square degrees of the extragalactic sky visible from the northern hemisphere. The Legacy Surveys have just published their sixth data release (DR6) which covers ~4000 square degrees, primarily north of declination +32 degrees.

    The Legacy Surveys DR6 release includes images and catalogs based on z-band data from the Mayall z-band Legacy Survey (MzLS; PI Arjun Dey), r- and g-band data from the Beijing-Arizona Sky Survey (BASS; PIs Xu Zhou and Xiaohui Fan), and mid-infrared photometry from the Wide-Field Infrared Survey Explorer (WISE) satellite for all optically detected sources. The WISE photometry is measured on new coadded images from the WISE mission and its subsequent reactivation as NEOWISE. DR6 includes astrometry, photometry and shape parameters for approximately 310 million sources. Combined with DR5, the Legacy Surveys catalogs contain information on roughly 990 million astronomical objects.

    The primary motivation behind the Legacy Surveys is to providing targeting data for the Dark Energy Spectroscopy Instrument (DESI) surveys. DESI, which is currently being installed at the Mayall 4m telescope at Kitt Peak, will probe the largest volume of the universe to date by compiling distances to 30 million galaxies and quasars, reaching further out than previous work, and providing us with a new 3-D map of the universe. Comparing the observed structures to predictions from cosmological models will tell us about the nature of dark energy, the distribution of dark matter, and the backbone structure of the matter distribution in the universe onto which the galaxies are painted.

    The ~4000 sq deg footprint covered by the latest DR6 release complements the ~10,000 sq. deg. footprint covered by the DR5 release. The DR5 and DR6 releases overlap in a strip in the north Galactic cap near declination +32 and in some scattered equatorial fields.

    In addition to a broader footprint and improved depth, the substantially increased overlap with the SDSS/BOSS spectroscopic survey creates exciting opportunities to conduct a variety of astrophysical studies (e.g., galaxy evolution, searching for high-redshift quasars, probing stellar populations, or the discovery of moving objects). The astronomical community is invited to conduct science projects and get in touch with the LS team and/or NOAO Data Lab team as needed.

    As in previous data releases, DR6 includes images, photometric catalogs, as well as an Image Gallery compiled by LS team member John Moustakas. The DR6 Gallery includes different categories of astronomical objects such as globular clusters, spiral disk galaxies, lenticular or elliptical galaxies (see Figures 1 & 2). Many more beautiful examples can be discovered by exploring interactively in the online sky viewer.

    We encourage usage of the data from the Legacy Surveys. The DR6 data products are available through: [1] direct access through the Legacy Survey Team website; [2] the NOAO Science Archive; and [3] the NOAO Data Lab. The NOAO Science Archive provides access to both the DR6 raw, and processed images. The NOAO Data Lab provides tools to access databases containing the catalogs. The Data Lab tools enable complex user queries and analyses of the data using a Jupyter Notebook server, a Simple Image Access (SIA) service and a TAP handle (which allows, for example, users to connect to the databases via commonly used tools such as TOPCAT). Example Jupyter Notebooks are also provided to users. We also note opportunities for combined analyses using other datasets accessible through the Data Lab such as the first data release from the Dark Energy Survey (DES), and the NOAO Source Catalog (NSC).

    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

    The next data release of the Legacy Surveys is planned for July 2018, and will include all DECam data obtained by the survey through March 2018.

    See the full article here .

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    NOAO News
    NOAO is the US national research & development center for ground-based night time astronomy. In particular, NOAO is enabling the development of the US optical-infrared (O/IR) System, an alliance of public and private observatories allied for excellence in scientific research, education and public outreach.

    Our core mission is to provide public access to qualified professional researchers via peer-review to forefront scientific capabilities on telescopes operated by NOAO as well as other telescopes throughout the O/IR System. Today, these telescopes range in aperture size from 2-m to 10-m. NOAO is participating in the development of telescopes with aperture sizes of 20-m and larger as well as a unique 8-m telescope that will make a 10-year movie of the Southern sky.

    In support of this mission, NOAO is engaged in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe, from planets orbiting other stars to the most distant galaxies in the Universe.

    To communicate the excitement of such world-class scientific research and technology development, NOAO has developed a nationally recognized Education and Public Outreach program. The main goals of the NOAO EPO program are to inspire young people to become explorers in science and research-based technology, and to reach out to groups and individuals who have been historically under-represented in the physics and astronomy science enterprise.

    The National Optical Astronomy Observatory is proud to be a US National Node in the International Year of Astronomy, 2009.

    About Our Observatories:
    Kitt Peak National Observatory (KPNO)

    Kitt Peak

    Kitt Peak National Observatory (KPNO) has its headquarters in Tucson and operates the Mayall 4-meter, the 3.5-meter WIYN , the 2.1-meter and Coudé Feed, and the 0.9-meter telescopes on Kitt Peak Mountain, about 55 miles southwest of the city.

    Cerro Tololo Inter-American Observatory (CTIO)

    NOAO Cerro Tolo

    The Cerro Tololo Inter-American Observatory (CTIO) is located in northern Chile. CTIO operates the 4-meter, 1.5-meter, 0.9-meter, and Curtis Schmidt telescopes at this site.

    The NOAO System Science Center (NSSC)

    Gemini North
    Gemini North

    Gemini South telescope
    Gemini South

    The NOAO System Science Center (NSSC) at NOAO is the gateway for the U.S. astronomical community to the International Gemini Project: twin 8.1 meter telescopes in Hawaii and Chile that provide unprecendented coverage (northern and southern skies) and details of our universe.

    NOAO is managed by the Association of Universities for Research in Astronomy under a Cooperative Agreement with the National Science Foundation.

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  • richardmitnick 10:53 am on April 3, 2018 Permalink | Reply
    Tags: Astronomers Have Detected 72 Incredibly Bright Explosions Caused by a Mysterious Source, , , , , DES - Dark Energy Survey, ,   

    From U Southampton via Science Alert: “Astronomers Have Detected 72 Incredibly Bright Explosions, Caused by a Mysterious Source” 

    U Southampton bloc

    University of Southampton

    ScienceAlert

    Science Alert

    3 APR 2018
    FIONA MACDONALD

    1
    (M. Pursiainen/University of Southampton)

    We have no idea where these came from.

    Astronomers have detected 72 incredibly bright and quick events flashing across a recent sky survey – and they’re struggling to understand where they came from.
    The mysterious explosions are similar in brightness to supernovae – the final, gigantic explosions that extinguish stars.

    But supernovae can be seen lighting up the sky for several months or more. In contrast, these 72 mysterious explosions were visible from a week to a month – which is incredibly brief on a cosmological timeframe. You can see two examples of the newly detected rapid events in yellow on the graph below, compared to two typical supernovae types (red and purple).

    2
    (M. Pursiainen/University of Southampton)

    The rapid events are so far known only as transients, and were detected in data from the Dark Energy Survey Supernova Programme (DES-SN).

    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

    The DES-SN is an international effort that’s hunting down supernovae to better understand dark energy, the hypothetical force thought to be driving the expansion of our Universe.

    By tracking these bright flashes of exploding stars, researchers hope to get a better understanding of exactly how fast the Universe is spreading out. But within that data, the international team of astronomers also noticed a number of other, more rapid explosive events – and they’re not sure what’s causing them.

    Lead image is one of the transient events photographed from eight days before maximum brightness to 18 days afterwards.

    This transient event took place 4 billion light years away.

    “The DES-SN survey is there to help us understand dark energy, itself entirely unexplained. That survey then also reveals many more unexplained transients than seen before,” says one of the astronomers, Miika Pursiainen from the University of Southampton.

    “If nothing else, our work confirms that astrophysics and cosmology are still sciences with a lot of unanswered questions!” So far there’s a lot we don’t know. But what’s clear is that the events are both incredibly hot in temperature, and large in scale – with temperatures ranging from 10,000 to 30,000 degrees Celsius (18,000 to 54,000 degrees Fahrenheit).
    The explosions also range in size, stretching from several to up to a hundred times the distance from Earth to the Sun (Earth is 150 million kilometres or 93 million miles from the Sun). Even stranger, the explosions seem to be expanding and cooling as they evolve in time. It’s still early days, but there are already a few ideas circulating on what they could be. One option is that this is a strange, never-before-seen type of supernova where the star sheds a lot of material before it explodes. In this scenario, the star could become completely enveloped by a shroud of matter, which becomes incredibly hot. It’s this hot cloud of matter that the astronomers are detecting rather than the star itself.

    There’s also the possibility that we’re seeing a newly discovered supernova in action.

    Just last week, researchers discovered a brand new explosive type of star death. The newly discovered supernova, KSN 2015K, peaked in brightness and then faded completely in under a month – 10 times faster than other supernovae of similar brightness. In the case of KSN 2015K, researchers think the star was shrouded by a cocoon of dust it had already ejected – only becoming visible after the dust was blasted away by the supernova’s shockwave. It’s unclear if these fast transients could be further evidence of this newfound star death in action, or represent an entirely new astronomical phenomenon. To test these hypotheses – or come up with other options – the team needs a lot more data. They’re going to continue to use a telescope in the Chilean Andes to monitor the night sky for traces of these explosions, and get a sense of why they occur, and how often.One important thing they’ll be looking for is if these events are more or less common, compared to ‘standard’ supernovae. The team also hasn’t published their detections in a peer-reviewed journal as yet, so there’s still the opportunity for other researchers to add insights and alternative explanations. We still have a lot to learn, but we’ll make one prediction – this won’t be the last you’ll hear about these 72 explosions.

    The results were presented on Tuesday 3 April at the European Week of Astronomy and Space Science in Liverpool, UK.

    See the full article here .

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    U Southampton campus

    The University of Southampton is a world-class university built on the quality and diversity of our community. Our staff place a high value on excellence and creativity, supporting independence of thought, and the freedom to challenge existing knowledge and beliefs through critical research and scholarship. Through our education and research we transform people’s lives and change the world for the better.

    Vision 2020 is the basis of our strategy.

    Since publication of the previous University Strategy in 2010 we have achieved much of what we set out to do against a backdrop of a major economic downturn and radical change in higher education in the UK.

    Vision 2020 builds on these foundations, describing our future ambition and priorities. It presents a vision of the University as a confident, growing, outwardly-focused institution that has global impact. It describes a connected institution equally committed to education and research, providing a distinctive educational experience for its students, and confident in its place as a leading international research university, achieving world-wide impact.

     
  • richardmitnick 7:03 pm on January 10, 2018 Permalink | Reply
    Tags: , , , , DES - Dark Energy Survey,   

    From FNAL: “Dark Energy Survey publicly releases first three years of data” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    January 10, 2018

    Also announces discovery of eleven stellar streams, evidence of small galaxies being eaten by the Milky Way.

    1
    This image shows the full area of sky mapped by the Dark Energy Survey and the 11 newly discovered stellar streams. Four of the streams in this diagram — ATLAS, Molonglo, Phoenix and Tucana III – were previously known. The others were discovered using the Dark Energy Camera, one of the most powerful astronomical cameras on Earth. Image: Dark Energy Survey

    At a special session held during the American Astronomical Society meeting in Washington, D.C., scientists on the Dark Energy Survey (DES) announced today the public release of their first three years of data.

    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

    “There are all kinds of discoveries waiting to be found in the data. While DES scientists are focused on using it to learn about dark energy, we wanted to enable astronomers to explore these images in new ways, to improve our understanding of the universe,” said Dark Energy Survey Data Management Project Scientist Brian Yanny of the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

    “The great thing about a big astronomical survey like this is that it also opens a door to many other studies, like the new stellar streams,” added Adam Bolton, associate director for the Community Science and Data Center at the National Optical Astronomy Observatory (NOAO). “With the DES data now available as a ‘digital sky,’ accessible to all, my hope is that these data will lead to the crowdsourcing of new and unexpected discoveries.”

    The DES data can be accessed online.

    This first major release of data from the Survey includes information on about 400 million astronomical objects, including distant galaxies billions of light-years away as well as stars in our own galaxy.

    DES scientists are using this data to learn more about dark energy, the mysterious force believed to be accelerating the expansion of the universe, and presented some of their preliminary cosmological findings in the special session. As part of that session, DES scientists also announced today the discovery of 11 new stellar streams, remnants of smaller galaxies torn apart and devoured by our Milky Way.

    The public release of the first three years of DES data fulfills a commitment scientists on the survey made to share their findings with the astronomy community and the public. The data cover the full DES footprint – about 5,000 square degrees, or one eighth of the entire sky — and include roughly 40,000 exposures taken with the Dark Energy Camera. The images correspond to hundreds of terabytes of data and are being released along with catalogs of hundreds of millions of galaxies and stars.

    The Dark Energy Camera, the primary observation tool of the Dark Energy Survey, is one of the most powerful digital imaging devices in existence. It was built and tested at Fermilab, the lead laboratory on the Dark Energy Survey, and is mounted on the National Science Foundation’s 4-meter Blanco telescope, part of the Cerro Tololo Inter-American Observatory in Chile, a division of NOAO. The DES images are processed by a team at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign.

    “We’re excited that this release of high-quality imaging data is now accessible to researchers around the world,” said Matias Carrasco Kind, DES release scientist at NCSA. “While DES was designed with the goal of understanding dark energy and dark matter, the huge amount of data in these images and catalogs will bring new scientific applications, challenges, and opportunities for discovery to astronomers and data scientists. In collaboration, NCSA, NOAO and the LIneA group in Brazil are providing the tools and resources to access and analyze this rich and robust data set.”

    One new discovery enabled by the data set is the detection of 11 new streams of stars around our Milky Way. Our home galaxy is surrounded by a massive halo of dark matter, which exerts a powerful gravitational pull on smaller, nearby galaxies. The Milky Way grows by pulling in, ripping apart and absorbing these smaller systems. As stars are torn away, they form streams across the sky that can be detected using the Dark Energy Camera. Even so, stellar streams are extremely difficult to find since they are composed of relatively few stars spread out over a large area of sky.

    “It’s exciting that we found so many stellar streams,” said astrophysicist Alex Drlica-Wagner of Fermilab. “We can use these streams to measure the amount, distribution and clumpiness of dark matter in the Milky Way. Studies of stellar streams will help constrain the fundamental properties of dark matter.”

    Prior to the new discoveries by DES, only about two dozen stellar streams had been discovered. Many of them were found by the Sloan Digital Sky Survey, a precursor to the Dark Energy Survey. The effort to detect new stellar streams in the Dark Energy Survey was led by University of Chicago graduate student Nora Shipp.

    “We’re interested in these streams because they teach us about the formation and structure of the Milky Way and its dark matter halo. Stellar streams give us a snapshot of a larger galaxy being built out of smaller ones,” Shipp said. “These discoveries are possible because DES is the widest, deepest and best-calibrated survey out there.”

    Since there is no universally accepted naming convention for stellar streams, the Dark Energy Survey has reached out to schools in Chile and Australia, asking young students to select names. Students and their teachers have worked together to name the streams after aquatic words in native languages from northern Chile and aboriginal Australia. Read more about the names in Symmetry magazine.

    Read the papers drawn from the first years of DES data online. An animation of several of the newly discovered streams can be seen on Fermilab’s website.

    DES plans one more major public data release, after the survey is completed, which will include nearly twice as many exposures as in this release.

    “This result is an excellent example of how ‘data mining’ — the exploration of large data sets — leads to new discoveries,” said Richard Green, director of the National Science Foundation’s (NSF) Division of Astronomical Sciences. “NSF is investing in this approach through our foundationwide ‘Harnessing the Data Revolution’ initiative, which is encouraging fundamental research in data science. We’re expecting a drumbeat of exciting discoveries, particularly when the Large Synoptic Survey Telescope data floodgates are opened!”

    This work is supported in part by the U.S. Department of Energy Office of Science.

    The Dark Energy Survey is a collaboration of more than 400 scientists from 26 institutions in seven countries. Funding for the DES Projects has been provided by the U.S. Department of Energy Office of Science, U.S. National Science Foundation, Ministry of Science and Education of Spain, Science and Technology Facilities Council of the United Kingdom, Higher Education Funding Council for England, ETH Zurich for Switzerland, National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and AstroParticle Physics at Ohio State University, Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and Ministério da Ciência e Tecnologia, Deutsche Forschungsgemeinschaft, and the collaborating institutions in the Dark Energy Survey, the list of which can be found at http://www.darkenergysurvey.org/collaboration.

    Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. NSF is an independent federal agency created by Congress in 1950 to promote the progress of science. NSF supports basic research and people to create knowledge that transforms the future.

    NCSA at the University of Illinois at Urbana-Champaign provides supercomputing and advanced digital resources for the nation’s science enterprise. At NCSA, University of Illinois faculty, staff, students and collaborators from around the globe use advanced digital resources to address research grand challenges for the benefit of science and society. NCSA has been advancing one third of the Fortune 50® for more than 30 years by bringing industry, researchers and students together to solve grand challenges at rapid speed and scale. For more information, please visit http://www.ncsa.illinois.edu.

    See the full article here .

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    FNAL Icon

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

     
  • richardmitnick 6:16 pm on January 10, 2018 Permalink | Reply
    Tags: , , , , , DES - Dark Energy Survey,   

    From BNL: “Dark Energy Survey Publicly Releases First Three Years of Data” 

    Brookhaven Lab

    Karen McNulty Walsh,
    (631) 344-8350
    kmcnulty@bnl.gov

    Peter Genzer,
    (631) 344-3174
    genzer@bnl.gov

    Also announces discovery of eleven stellar streams, evidence of small galaxies being eaten by the Milky Way

    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

    At a special session held during the American Astronomical Society meeting in Washington, D.C., scientists on the Dark Energy Survey (DES) announced today the public release of their first three years of data. This first major release of data from the Survey includes information on about 400 million astronomical objects, including distant galaxies billions of light years away as well as stars in our own galaxy.

    DES scientists are using this data to learn more about dark energy, the mysterious force believed to be accelerating the expansion of the universe, and presented some of their preliminary cosmological findings in the special session. As part of that session, DES scientists also announced today the discovery of eleven new stellar streams, remnants of smaller galaxies torn apart and devoured by our Milky Way.

    The public release of the first three years of DES data fulfills a commitment scientists on the survey made to share their findings with the astronomy community and the public. The data cover the full DES footprint – about 5,000 square degrees, or one eighth of the entire sky – and include roughly 40,000 exposures taken with the Dark Energy Camera. The images correspond to hundreds of terabytes of data and are being released along with catalogs of hundreds of millions of galaxies and stars.

    “There are all kinds of discoveries waiting to be found in the data,” said Dark Energy Survey Data Management Project Scientist Brian Yanny of the U.S. Department of Energy’s Fermi National Accelerator Laboratory. “While DES scientists are focused on using it to learn about dark energy, we wanted to enable astronomers to explore these images in new ways, to improve our understanding of the universe.”

    “The great thing about a big astronomical survey like this is that it also opens a door to many other studies, like the new stellar streams,” added Adam Bolton, Associate Director for the Community Science and Data Center at the National Optical Astronomy Observatory (NOAO). “With the DES data now available as a ‘digital sky,’ accessible to all, my hope is that these data will lead to the crowdsourcing of new and unexpected discoveries.”

    The DES data can be accessed online here: https://des.ncsa.illinois.edu/releases/dr1.

    1
    This image shows the full area of sky mapped by the Dark Energy Survey, and the eleven newly discovered stellar streams. Four of the streams in this diagram – ATLAS, Molonglo, Phoenix and Tucana III – were previously known. The others were discovered using the Dark Energy Camera, one of the most powerful astronomical cameras on Earth. Image credit: Dark Energy Survey.

    The Dark Energy Camera, the primary observation tool of the Dark Energy Survey, is one of the most powerful digital imaging devices in existence. It was built and tested at Fermilab, the lead laboratory on the Dark Energy Survey, and is mounted on the National Science Foundation’s 4-meter Blanco telescope, part of the Cerro Tololo Inter-American Observatory in Chile, a division of NOAO. The DES images are processed by a team at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign.

    “We’re excited that this release of high-quality imaging data is now accessible to researchers around the world,” said Matias Carrasco Kind, DES release scientist at NCSA. “While DES was designed with the goal of understanding dark energy and dark matter, the huge amount of data in these images and catalogs will bring new scientific applications, challenges, and opportunities for discovery to astronomers and data scientists. In collaboration, NCSA, NOAO and the LIneA group in Brazil are providing the tools and resources to access and analyze this rich and robust data set.”

    One new discovery enabled by the data set is the detection of eleven new streams of stars around our Milky Way. Our home galaxy is surrounded by a massive halo of dark matter, which exerts a powerful gravitational pull on smaller, nearby galaxies. The Milky Way grows by pulling in, ripping apart and absorbing these smaller systems. As stars are torn away, they form streams across the sky that can be detected using the Dark Energy Camera. Even so, stellar streams are extremely difficult to find since they are composed of relatively few stars spread out over a large area of sky.

    “It’s exciting that we found so many stellar streams,” said astrophysicist Alex Drlica-Wagner of Fermilab. “We can use these streams to measure the amount, distribution, and clumpiness of dark matter in the Milky Way. Studies of stellar streams will help constrain the fundamental properties of dark matter.”

    Prior to the new discoveries by DES, only about two dozen stellar streams had been discovered. Many of them were found by the Sloan Digital Sky Survey, a precursor to the Dark Energy Survey. The effort to detect new stellar streams in the Dark Energy Survey was led by University of Chicago graduate student Nora Shipp.

    “We’re interested in these streams because they teach us about the formation and structure of the Milky Way and its dark matter halo. Stellar streams give us a snapshot of a larger galaxy being built out of smaller ones,” said Shipp. “These discoveries are possible because DES is the widest, deepest and best-calibrated survey out there.”

    Since there is no universally accepted naming convention for stellar streams, the Dark Energy Survey has reached out to schools in Chile and Australia, asking young students to select names. Students and their teachers have worked together to name the streams after aquatic words in native languages from northern Chile and aboriginal Australia. Read more about the names in this story from Symmetry: https://www.symmetrymagazine.org/article/rivers-in-the-sky.

    Read the papers drawn from the first years of DES data online here: https://www.darkenergysurvey.org/dr1-data-release-papers. An animation of several of the newly discovered streams can be seen here: http://home.fnal.gov/~kadrlica/movies/residual_q1_v17p2_label.gif.

    See the full article here .

    [It is really surprising to me that I could find no similar article at FNAL, just a bunch of .pdf’s]

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
    i1

     
  • richardmitnick 1:51 pm on December 11, 2017 Permalink | Reply
    Tags: , , , Binary neutron stars, , DES - Dark Energy Survey, , ,   

    From DES: “What the galaxy that hosted the gravitational wave event GW170817 can teach us about binary neutron stars” 

    Dark Energy Icon

    The Dark Energy Survey

    November 22, 2017 [Just now in social media.]
    Antonella Palmese
    Sunayana Bhargava

    Astronomers know many facts about galaxies. For example, we know that their colours tell us about the stars inside them and how old they are. We also know that their shapes can tell us about how they formed. Past and current large-scale surveys such as the Dark Energy Survey (DES) observe millions of galaxies at different distances, and therefore at different stages of their evolution. These galaxies can be catalogued and characterized in a number of different ways. However, one type of star system we know little about are binary neutron stars (BNS). The handful of confirmed binary neutron stars found have all been within our own galaxy.

    The optical counterpart to GW170817 was observed by the Dark Energy Camera (DECam) and other instruments to have come from a galaxy named NGC 4993, which is 130 million light years away from us. This event was likely produced by a binary neutron star merger. Antonella Palmese, together with other galaxy evolution and gravitational wave experts (Will Hartley, Marcelle Soares-Santos, Jim Annis, Huan Lin, Christopher Conselice, Federica Tarsitano and more) asked the question: what can we learn about the stars in NGC 4993? How did this binary system emerge in the overall history of the galaxy? Although we only have one snapshot of this galaxy, which is precisely 130 million years old, we can make use of other properties to infer how this galaxy evolved over cosmic time.

    At first glance, NGC 4993 looks like a normal, old massive elliptical galaxy (left panel in Figure 1), known by astronomers as an “early type galaxy”. But if we examine it more closely, we see that it contains shell structures: arcs of brighter stellar densities around the center of the galaxy. If we consider the profile of a typical, early type galaxy (see middle panel in Figure 1) and subtract it from the profile of NGC 4993, we notice key differences that help us characterize the kind of environment needed for binary neutron stars to form.

    1
    Figure 1. Left panel: DECam image of NCG 4993. Shell structures indicative of a recent galaxy merger are clearly visible. Middle panel: r-band residuals after subtraction of a Sérsic light profile. Right panel: F606W-band HST ACS image with a 3 component galaxy model subtracted. Dust lanes crossing the centre of the galaxy are evident after this subtraction. The green lines show the position of the transient.

    A number of papers starting from the 1980s have supported, with simulations and observations, the idea that these kind of shell structures are the debris of a recent merger between two galaxies (see a simulation example: http://hubblesite.org/video/558/news/4-galaxies ). During the merger, the stars from the smaller galaxy that passed close to NGC4993 millions of years ago were stripped away. As a result, many stars are concentrated in these arc-like regions. From the innermost shell position and the velocity of stars, we estimate that the shells in this galaxy should be visible for ~200 million years before dispersing. This means, if we still see them, the galaxy merger must have happened up to 200 million years before the BNS coalescence (see Figure 2 for a timeline). Could the dynamics of this galaxy merger be involved in the formation of the GW progenitor?

    3
    Figure 2. Timeline of NGC 4993

    DES only observes in optical photometric bands so we added information from infrared and spectroscopic surveys to study this galaxy in greater detail. We find more evidence for a recent galaxy merger (e.g. dust lanes, right panel of Figure 1, and two different stellar populations). We also find that the age of most of the stars in this galaxy is ~11 billion years old – only a few billion years younger than the Universe! This means that during its ‘recent’ stages, this galaxy has not been forming stars.

    Most of the current models for the formation of BNS suggest that they begin as a binary of two massive stars from a star formation event. During the evolution of the massive star binary, both stars will become supernova. If the gravitational force between the stars is strong enough to keep them bound against the force of the supernovae explosions, they become neutron stars in orbit until they coalesce. Simulations show us that neutron stars usually orbit around each other for ~500 million years before they merge, but it can take up to some billion years. Their lifetime before becoming neutron stars is much shorter than that.

    So if there was no recent star formation in NGC 4993, where did these massive stars, which go on to become neutron stars, come from? If they formed 11 billion years ago with other stars in the galaxy, why did they only merge now? Our work shows that it is unlikely that the BNS was formed ordinarily. We do not expect this BNS to be so old given the current knowledge of their expected lifetime from simulations. We instead suggest that the formation of the BNS was not through traditional channels. Instead, dynamical interactions between stars due to the galaxy merger might have caused the two neutron stars to form a binary or to coalesce. The plan for the future is to discover many more of these BNS systems inside their galactic hosts. With more data, it will be possible to determine how galaxies are able to produce the right conditions for this energetic dance of dense bodies to occur, creating ripples of energy (gravitational waves) that teach us about the Universe.

    See the full article here .

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    DECam, built at FNAL
    DECam, built at FNAL
    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco Telescope at Cerro Tololo which houses the DECAm

    The Dark Energy Survey (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 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and [has mounted] it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Started in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

     
  • richardmitnick 8:04 am on November 27, 2017 Permalink | Reply
    Tags: , , , DES - Dark Energy Survey, , , , , Simulating the universe using Einstein’s theory of gravity may solve cosmic puzzles   

    From ScienceNews: “Simulating the universe using Einstein’s theory of gravity may solve cosmic puzzles” 

    ScienceNews bloc

    ScienceNews

    November 25, 2017
    Emily Conover

    Until recently, simulations of the universe haven’t given its lumps their due.

    1
    UNEVEN TERRAIN Universe simulations that consider general relativity (one shown) may shift knowledge of the cosmos. James Mertens

    If the universe were a soup, it would be more of a chunky minestrone than a silky-smooth tomato bisque.

    Sprinkled with matter that clumps together due to the insatiable pull of gravity, the universe is a network of dense galaxy clusters and filaments — the hearty beans and vegetables of the cosmic stew. Meanwhile, relatively desolate pockets of the cosmos, known as voids, make up a thin, watery broth in between.

    Until recently, simulations of the cosmos’s history haven’t given the lumps their due. The physics of those lumps is described by general relativity, Albert Einstein’s theory of gravity. But that theory’s equations are devilishly complicated to solve. To simulate how the universe’s clumps grow and change, scientists have fallen back on approximations, such as the simpler but less accurate theory of gravity devised by Isaac Newton.

    Relying on such approximations, some physicists suggest, could be mucking with measurements, resulting in a not-quite-right inventory of the cosmos’s contents. A rogue band of physicists suggests that a proper accounting of the universe’s clumps could explain one of the deepest mysteries in physics: Why is the universe expanding at an increasingly rapid rate?

    The accepted explanation for that accelerating expansion is an invisible pressure called dark energy. In the standard theory of the universe, dark energy makes up about 70 percent of the universe’s “stuff” — its matter and energy. Yet scientists still aren’t sure what dark energy is, and finding its source is one of the most vexing problems of cosmology.

    Perhaps, the dark energy doubters suggest, the speeding up of the expansion has nothing to do with dark energy. Instead, the universe’s clumpiness may be mimicking the presence of such an ethereal phenomenon.

    Most physicists, however, feel that proper accounting for the clumps won’t have such a drastic impact. Robert Wald of the University of Chicago, an expert in general relativity, says that lumpiness is “never going to contribute anything that looks like dark energy.” So far, observations of the universe have been remarkably consistent with predictions based on simulations that rely on approximations.

    _____________________________________________________________________________

    Growing a lumpy universe

    The universe has gradually grown lumpier throughout its history. During inflation, rapid expansion magnified tiny quantum fluctuations into minute density variations. Over time, additional matter glommed on to dense spots due to the stronger gravitational pull from the extra mass. After 380,000 years, those blips were imprinted as hot and cold spots in the cosmic microwave background, the oldest light in the universe. Lumps continued growing for billions of years, forming stars, planets, galaxies and galaxy clusters.

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    _____________________________________________________________________________

    As observations become more detailed, though, even slight inaccuracies in simulations could become troublesome. Already, astronomers are charting wide swaths of the sky in great detail, and planning more extensive surveys. To translate telescope images of starry skies into estimates of properties such as the amount of matter in the universe, scientists need accurate simulations of the cosmos’s history. If the detailed physics of clumps is important, then simulations could go slightly astray, sending estimates off-kilter. Some scientists already suggest that the lumpiness is behind a puzzling mismatch of two estimates of how fast the universe is expanding.

    Researchers are attempting to clear up the debate by conquering the complexities of general relativity and simulating the cosmos in its full, lumpy glory. “That is really the new frontier,” says cosmologist Sabino Matarrese of the University of Padua in Italy, “something that until a few years ago was considered to be science fiction.” In the past, he says, scientists didn’t have the tools to complete such simulations. Now researchers are sorting out the implications of the first published results of the new simulations. So far, dark energy hasn’t been explained away, but some simulations suggest that certain especially sensitive measurements of how light is bent by matter in the universe might be off by as much as 10 percent.

    Soon, simulations may finally answer the question: How much do lumps matter? The idea that cosmologists might have been missing a simple answer to a central problem of cosmology incessantly nags some skeptics. For them, results of the improved simulations can’t come soon enough. “It haunts me. I can’t let it go,” says cosmologist Rocky Kolb of the University of Chicago.

    Smooth universe

    By observing light from different eras in the history of the cosmos, cosmologists can compute the properties of the universe, such as its age and expansion rate. But to do this, researchers need a model, or framework, that describes the universe’s contents and how those ingredients evolve over time. Using this framework, cosmologists can perform computer simulations of the universe to make predictions that can be compared with actual observations.

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    COSMIC WEB Clumps and filaments of matter thread through a simulated universe 2 billion light years across. This simulation incorporates some aspects of Einstein’s theory of general relativity, allowing for detailed results while avoiding the difficulties of the full-fledged theory.

    After Einstein introduced his theory in 1915, physicists set about figuring out how to use it to explain the universe. It wasn’t easy, thanks to general relativity’s unwieldy, difficult-to-solve suite of equations. Meanwhile, observations made in the 1920s indicated that the universe wasn’t static as previously expected; it was expanding. Eventually, researchers converged on a solution to Einstein’s equations known as the Friedmann-Lemaître-Robertson-Walker metric. Named after its discoverers, the FLRW metric describes a simplified universe that is homogeneous and isotropic, meaning that it appears identical at every point in the universe and in every direction. In this idealized cosmos, matter would be evenly distributed, no clumps. Such a smooth universe would expand or contract over time.

    A smooth-universe approximation is sensible, because when we look at the big picture, averaging over the structures of galaxy clusters and voids, the universe is remarkably uniform. It’s similar to the way that a single spoonful of minestrone soup might be mostly broth or mostly beans, but from bowl to bowl, the overall bean-to-broth ratios match.

    In 1998, cosmologists revealed that not only was the universe expanding, but its expansion was also accelerating (SN: 2/2/08, p. 74). Observations of distant exploding stars, or supernovas, indicated that the space between us and them was expanding at an increasing clip. But gravity should slow the expansion of a universe evenly filled with matter. To account for the observed acceleration, scientists needed another ingredient, one that would speed up the expansion. So they added dark energy to their smooth-universe framework.

    Now, many cosmologists follow a basic recipe to simulate the universe — treating the cosmos as if it has been run through an imaginary blender to smooth out its lumps, adding dark energy and calculating the expansion via general relativity. On top of the expanding slurry, scientists add clumps and track their growth using approximations, such as Newtonian gravity, which simplifies the calculations.

    In most situations, Newtonian gravity and general relativity are near-twins. Throw a ball while standing on the surface of the Earth, and it doesn’t matter whether you use general relativity or Newtonian mechanics to calculate where the ball will land — you’ll get the same answer. But there are subtle differences. In Newtonian gravity, matter directly attracts other matter. In general relativity, gravity is the result of matter and energy warping spacetime, creating curves that alter the motion of objects (SN: 10/17/15, p. 16). The two theories diverge in extreme gravitational environments. In general relativity, for example, hulking black holes produce inescapable pits that reel in light and matter (SN: 5/31/14, p. 16). The question, then, is whether the difference between the two theories has any impact in lumpy-universe simulations.

    Most cosmologists are comfortable with the status quo simulations because observations of the heavens seem to fit neatly together like interlocking jigsaw puzzle pieces. Predictions based on the standard framework agree remarkably well with observations of the cosmic microwave background — ancient light released when the universe was just 380,000 years old (SN: 3/21/15, p. 7). And measurements of cosmological parameters — the fraction of dark energy and matter, for example — are generally consistent, whether they are made using the light from galaxies or the cosmic microwave background [CMB].

    CMB per ESA/Planck


    ESA/Planck

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    An image from the Two-Micron All Sky Survey of 1.6 million galaxies in infrared light reveals how matter clumps into galaxy clusters and filaments. Future large-scale surveys may require improved simulations that use general relativity to track the evolution of lumps over time. T.H. Jarrett, J. Carpenter & R. Hurt, obtained as part of 2MASS, a joint project of Univ. of Massachusetts and the Infrared Processing and Analysis Center/Caltech, funded by NASA and NSF.


    Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, and at the Cerro Tololo Inter-American Observatory near La Serena, Chile.

    Dethroning dark energy

    Some cosmologists hope to explain the universe’s accelerating expansion by fully accounting for the universe’s lumpiness, with no need for the mysterious dark energy.

    These researchers argue that clumps of matter can alter how the universe expands, when the clumps’ influence is tallied up over wide swaths of the cosmos. That’s because, in general relativity, the expansion of each local region of space depends on how much matter is within. Voids expand faster than average; dense regions expand more slowly. Because the universe is mostly made up of voids, this effect could produce an overall expansion and potentially an acceleration. Known as backreaction, this idea has lingered in obscure corners of physics departments for decades, despite many claims that backreaction’s effect is small or nonexistent.

    Backreaction continues to appeal to some researchers because they don’t have to invent new laws of physics to explain the acceleration of the universe. “If there is an alternative which is based only upon traditional physics, why throw that away completely?” Matarrese asks.

    Most cosmologists, however, think explaining away dark energy just based on the universe’s lumps is unlikely. Previous calculations have indicated any effect would be too small to account for dark energy, and would produce an acceleration that changes in time in a way that disagrees with observations.

    “My personal view is that it’s a much smaller effect,” says astrophysicist Hayley Macpherson of Monash University in Melbourne, Australia. “That’s just basically a gut feeling.” Theories that include dark energy explain the universe extremely well, she points out. How could that be if the whole approach is flawed?

    New simulations by Macpherson and others that model how lumps evolve in general relativity may be able to gauge the importance of backreaction once and for all. “Up until now, it’s just been too hard,” says cosmologist Tom Giblin of Kenyon College in Gambier, Ohio.

    To perform the simulations, researchers needed to get their hands on supercomputers capable of grinding through the equations of general relativity as the simulated universe evolves over time. Because general relativity is so complex, such simulations are much more challenging than those that use approximations, such as Newtonian gravity. But, a seemingly distinct topic helped lay some of the groundwork: gravitational waves, or ripples in the fabric of spacetime.

    4
    SPECKLED SPACETIME A lumpy universe, recently simulated using general relativity, shows clumps of matter (pink and yellow) that beget stars and galaxies. H. Macpherson, Paul Lasky, Daniel Price.

    The Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, searches for the tremors of cosmic dustups such as colliding black holes (SN: 10/28/17, p. 8).


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

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    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    In preparation for this search, physicists honed their general relativity skills on simulations of the spacetime storm kicked up by black holes, predicting what LIGO might see and building up the computational machinery to solve the equations of general relativity. Now, cosmologists have adapted those techniques and unleashed them on entire, lumpy universes.

    The first lumpy universe simulations to use full general relativity were unveiled in the June 2016 Physical Review Letters. Giblin and colleagues reported their results simultaneously with Eloisa Bentivegna of the University of Catania in Italy and Marco Bruni of the University of Portsmouth in England.

    So far, the simulations have not been able to account for the universe’s acceleration. “Nearly everybody is convinced [the effect] is too small to explain away the need for dark energy,” says cosmologist Martin Kunz of the University of Geneva. Kunz and colleagues reached the same conclusion in their lumpy-universe simulations, which have one foot in general relativity and one in Newtonian gravity. They reported their first results in Nature Physics in March 2016.

    Backreaction aficionados still aren’t dissuaded. “Before saying the effect is too small to be relevant, I would, frankly, wait a little bit more,” Matarrese says. And the new simulations have potential caveats. For example, some simulated universes behave like an old arcade game — if you walk to one edge of the universe, you cross back over to the other side, like Pac-Man exiting the right side of the screen and reappearing on the left. That geometry would suppress the effects of backreaction in the simulation, says Thomas Buchert of the University of Lyon in France. “This is a good beginning,” he says, but there is more work to do on the simulations. “We are in infancy.”

    Different assumptions in a simulation can lead to disparate results, Bentivegna says. As a result, she doesn’t think that her lumpy, general-relativistic simulations have fully closed the door on efforts to dethrone dark energy. For example, tricks of light might be making it seem like the universe’s expansion is accelerating, when in fact it isn’t.

    When astronomers observe far-away sources like supernovas, the light has to travel past all of the lumps of matter between the source and Earth. That journey could make it look like there’s an acceleration when none exists. “It’s an optical illusion,” Bentivegna says. She and colleagues see such an effect in a simulation reported in March in the Journal of Cosmology and Astroparticle Physics. But, she notes, this work simulated an unusual universe, in which matter sits on a grid — not a particularly realistic scenario.

    For most other simulations, the effect of optical illusions remains small. That leaves many cosmologists, including Giblin, even more skeptical of the possibility of explaining away dark energy: “I feel a little like a downer,” he admits.

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    Lumps (gray) within this simulated universe change the path light takes (yellow lines), potentially affecting observations. Matter bends space, slightly altering the light’s trajectory from that in a smooth universe. James Mertens.

    Surveying the skies

    Subtle effects of lumps could still be important. In Hans Christian Andersen’s The Princess and the Pea, the princess felt a tiny pea beneath an impossibly tall stack of mattresses. Likewise, cosmologists’ surveys are now so sensitive that even if the universe’s lumps have a small impact, estimates could be thrown out of whack.

    The Dark Energy Survey, for example, has charted 26 million galaxies using the Victor M. Blanco Telescope in Chile, measuring how the light from those galaxies is distorted by the intervening matter on the journey to Earth.

    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

    In a set of papers posted online August 4 at arXiv.org, scientists with the Dark Energy Survey reported new measurements of the universe’s properties, including the amount of matter (both dark and normal) and how clumpy that matter is (SN: 9/2/17, p. 32). The results are consistent with those from the cosmic microwave background [CMB] — light emitted billions of years earlier.

    To make the comparison, cosmologists took the measurements from the cosmic microwave background, early in the universe, and used simulations to extrapolate to what galaxies should look like later in the universe’s history. It’s like taking a baby’s photograph, precisely computing the number and size of wrinkles that should emerge as the child ages and finding that your picture agrees with a snapshot taken decades later. The matching results so far confirm cosmologists’ standard picture of the universe — dark energy and all.

    “So far, it has not yet been important for the measurements that we’ve made to actually include general relativity in those simulations,” says Risa Wechsler, a cosmologist at Stanford University and a founding member of the Dark Energy Survey. But, she says, for future measurements, “these effects could become more important.” Cosmologists are edging closer to Princess and the Pea territory.

    Those future surveys include the Dark Energy Spectroscopic Instrument, DESI, set to kick off in 2019 at Kitt Peak National Observatory near Tucson; the European Space Agency’s Euclid satellite, launching in 2021; and the Large Synoptic Survey Telescope in Chile, which is set to begin collecting data in 2023.

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory, Altitude 2,120 m (6,960 ft)

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

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

    ESA/Euclid spacecraft

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction 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.

    If cosmologists keep relying on simulations that don’t use general relativity to account for lumps, certain kinds of measurements of weak lensing — the bending of light due to matter acting like a lens — could be off by up to 10 percent, Giblin and colleagues reported at arXiv.org in July. “There is something that we’ve been ignoring by making approximations,” he says.

    That 10 percent could screw up all kinds of estimates, from how dark energy changes over the universe’s history to how fast the universe is currently expanding, to the calculations of the masses of ethereal particles known as neutrinos. “You have to be extremely certain that you don’t get some subtle effect that gets you the wrong answers,” Geneva’s Kunz says, “otherwise the particle physicists are going to be very angry with the cosmologists.”

    Some estimates may already be showing problem signs, such as the conflicting estimates of the cosmic expansion rate (SN: 8/6/16, p. 10). Using the cosmic microwave background, cosmologists find a slower expansion rate than they do from measurements of supernovas. If this discrepancy is real, it could indicate that dark energy changes over time. But before jumping to that conclusion, there are other possible causes to rule out, including the universe’s lumps.

    Until the issue of lumps is smoothed out, scientists won’t know how much lumpiness matters to the cosmos at large. “I think it’s rather likely that it will turn out to be an important effect,” Kolb says. Whether it explains away dark energy is less certain. “I want to know the answer so I can get on with my life.”

    See the full article here .

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  • richardmitnick 2:36 pm on November 14, 2017 Permalink | Reply
    Tags: , DECaPS, DES - Dark Energy Survey, , NOAO Science Archive, The DECam Plane Survey, The DECam Plane Survey (DECaPS)   

    From NOAO: “DECam Plane Survey Data Release: Catalogs and Images Now Available” 

    NOAO Banner

    11.14.17
    Eddie Schlafly (Lawrence Berkeley National Lab)

    A new publicly available data set offers a wealth of information on the structure of the disk of the Milky Way and its interstellar medium.

    The DECam Plane Survey (DECaPS), which uses the Dark Energy Camera (DECam) to observe the southern Galactic plane (dec < -30 degrees), has released data covering roughly one-third of the Milky Way’s disk: a swath within 5 degrees of the Galactic plane that extends over 1000 square degrees of the sky through Galactic longitudes between 5 degrees and -120 degrees. The survey reaches a depth of 23.7, 22.8, 22.2, 21.8, and 21.0 magnitudes in the g, r, i, z, and Y bands, roughly suitable for detecting main-sequence turn-off stars at the distance to the Galactic center through a reddening of 1.5 magnitudes E(B-V).

    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

    The data release includes images and catalogs. The full catalogs contain more than twenty billion detections of two billion objects, mostly corresponding to highly reddened stars deep in the Galactic disk. All of the images making up the survey can be browsed interactively through the DECam Legacy Survey viewer and are available through the NOAO Science Archive.

    1
    Some images from the DECaPS Data Release. Hover your mouse over the image to pause the slideshow. [This only works at the full article.]

    The DECam Plane Survey

    The DECam Plane Survey was designed to measure the fluxes of billions of stars in the southern Galactic plane to reveal the three-dimensional distribution of dust in the Milky Way. In concert with Pan-STARRS1 (PS1) observations of the northern Galactic plane, the survey results allow a full 360 degree map of the dust in the Milky Way.

    Pann-STARS telescope, U Hawaii, Mauna Kea, Hawaii, USA, 4,207 m (13,802 ft) above sea level

    DECaPS is not just an extension of PS1, however. It is significantly deeper than other wide-area surveys of the Galactic plane, reaching stars roughly one magnitude fainter than PS1 in individual images. The DECaPS pipeline is optimized for crowded fields of point sources, allowing precise photometry even in the inner Galaxy where the huge number of stars blend together in the typical 1″ seeing obtained by DECaPS.

    Nor is DECaPS just about dust. By studying many stars, the structure of the Milky Way’s disk can be characterized in detail. Color-magnitude diagrams from the survey show a rich array of stellar populations that vary from place to place within the Galaxy. The DECaPS catalog is only a first step intended to enable many different scientific analyses of the survey.

    Each part of the survey footprint was observed three times, usually on different nights, using the same tiling of the sky developed for the DECam Legacy Survey. This strategy was designed to enable precise photometric calibration, but it also provides some limited variability information about all of the observed stars. Observations for the survey took place over 22 nights from March 2016 to May 2017. The large etendue and low downtime of the DECam/Blanco system made this survey efficiency possible. Further details on the survey are available in a preprint by Schlafly et al. (2017).
    DECaPS Images

    Color images from DECaPS can be interactively browsed through the DECam Legacy Survey viewer, built by Dustin Lang. The three colors show the g, r, and z bands. Both the actual observations and “model observations” generated from the DECaPS catalogs and the pipeline-estimated PSF can be viewed, providing an immediate sense of the accuracy of the modeling. For example, compare the actual observations with the best-fit models in the viewer.

    All of the images making up the survey are also available through the NOAO Science Archive (select all images with Program Number 2016A-0323 or 2016B-0279, PI: Finkbeiner).

    Catalogs

    The DECam Plane Survey catalogs were constructed using a custom pipeline optimized for crowded stellar fields. The pipeline follows in the tradition of DAOPHOT, simultaneously fitting for the positions and fluxes of all of the stars in each image. This fit is performed by linearizing the problem and passing the optimization off to a large, sparse, linear-least-squares optimizer. In the densest regions, this can require simultaneously fitting the positions and fluxes of 60,000 stars per 1024×1024 pixel region.

    Each DECaPS image is independently analyzed. In order to provide multiband information, single-image catalogs are matched together, and detections within 0.5” of one another are considered to be detections of the same star. All of the detections of the same object are then grouped together to provide average photometry and astrometry of each star in each band. Both the single-image and band-merged catalogs are available at the survey web site.

    See the full article here .

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    NOAO is the US national research & development center for ground-based night time astronomy. In particular, NOAO is enabling the development of the US optical-infrared (O/IR) System, an alliance of public and private observatories allied for excellence in scientific research, education and public outreach.

    Our core mission is to provide public access to qualified professional researchers via peer-review to forefront scientific capabilities on telescopes operated by NOAO as well as other telescopes throughout the O/IR System. Today, these telescopes range in aperture size from 2-m to 10-m. NOAO is participating in the development of telescopes with aperture sizes of 20-m and larger as well as a unique 8-m telescope that will make a 10-year movie of the Southern sky.

    In support of this mission, NOAO is engaged in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe, from planets orbiting other stars to the most distant galaxies in the Universe.

    To communicate the excitement of such world-class scientific research and technology development, NOAO has developed a nationally recognized Education and Public Outreach program. The main goals of the NOAO EPO program are to inspire young people to become explorers in science and research-based technology, and to reach out to groups and individuals who have been historically under-represented in the physics and astronomy science enterprise.

    The National Optical Astronomy Observatory is proud to be a US National Node in the International Year of Astronomy, 2009.

    About Our Observatories:
    Kitt Peak National Observatory (KPNO)

    Kitt Peak

    Kitt Peak National Observatory (KPNO) has its headquarters in Tucson and operates the Mayall 4-meter, the 3.5-meter WIYN , the 2.1-meter and Coudé Feed, and the 0.9-meter telescopes on Kitt Peak Mountain, about 55 miles southwest of the city.

    Cerro Tololo Inter-American Observatory (CTIO)

    NOAO Cerro Tolo

    The Cerro Tololo Inter-American Observatory (CTIO) is located in northern Chile. CTIO operates the 4-meter, 1.5-meter, 0.9-meter, and Curtis Schmidt telescopes at this site.

    The NOAO System Science Center (NSSC)

    Gemini North
    Gemini North

    Gemini South telescope
    Gemini South

    The NOAO System Science Center (NSSC) at NOAO is the gateway for the U.S. astronomical community to the International Gemini Project: twin 8.1 meter telescopes in Hawaii and Chile that provide unprecendented coverage (northern and southern skies) and details of our universe.

    NOAO is managed by the Association of Universities for Research in Astronomy under a Cooperative Agreement with the National Science Foundation.

     
  • richardmitnick 9:00 pm on October 20, 2017 Permalink | Reply
    Tags: , , , , DES - Dark Energy Survey, , Neutron stars gravitational waves and all the gold in the universe, ,   

    From UCSC: “Neutron stars, gravitational waves, and all the gold in the universe” 

    UC Santa Cruz

    UC Santa Cruz

    14

    A UC Santa Cruz special report

    Tim Stephens

    Astronomer Ryan Foley says “observing the explosion of two colliding neutron stars” [see https://sciencesprings.wordpress.com/2017/10/17/from-ucsc-first-observations-of-merging-neutron-stars-mark-a-new-era-in-astronomy ]–the first visible event ever linked to gravitational waves–is probably the biggest discovery he’ll make in his lifetime. That’s saying a lot for a young assistant professor who presumably has a long career still ahead of him.

    2
    The first optical image of a gravitational wave source was taken by a team led by Ryan Foley of UC Santa Cruz using the Swope Telescope at the Carnegie Institution’s Las Campanas Observatory in Chile. This image of Swope Supernova Survey 2017a (SSS17a, indicated by arrow) shows the light emitted from the cataclysmic merger of two neutron stars. (Image credit: 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

    A neutron star forms when a massive star runs out of fuel and explodes as a supernova, throwing off its outer layers and leaving behind a collapsed core composed almost entirely of neutrons. Neutrons are the uncharged particles in the nucleus of an atom, where they are bound together with positively charged protons. In a neutron star, they are packed together just as densely as in the nucleus of an atom, resulting in an object with one to three times the mass of our sun but only about 12 miles wide.

    “Basically, a neutron star is a gigantic atom with the mass of the sun and the size of a city like San Francisco or Manhattan,” said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz.

    These objects are so dense, a cup of neutron star material would weigh as much as Mount Everest, and a teaspoon would weigh a billion tons. It’s as dense as matter can get without collapsing into a black hole.

    THE MERGER

    Like other stars, neutron stars sometimes occur in pairs, orbiting each other and gradually spiraling inward. Eventually, they come together in a catastrophic merger that distorts space and time (creating gravitational waves) and emits a brilliant flare of electromagnetic radiation, including visible, infrared, and ultraviolet light, x-rays, gamma rays, and radio waves. Merging black holes also create gravitational waves, but there’s nothing to be seen because no light can escape from a black hole.

    Foley’s team was the first to observe the light from a neutron star merger that took place on August 17, 2017, and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    Now, for the first time, scientists can study both the gravitational waves (ripples in the fabric of space-time), and the radiation emitted from the violent merger of the densest objects in the universe.

    3
    The UC Santa Cruz team found SSS17a by comparing a new image of the galaxy N4993 (right) with images taken four months earlier by the Hubble Space Telescope (left). The arrows indicate where SSS17a was absent from the Hubble image and visible in the new image from the Swope Telescope. (Image credits: Left, Hubble/STScI; Right, 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

    It’s that combination of data, and all that can be learned from it, that has astronomers and physicists so excited. The observations of this one event are keeping hundreds of scientists busy exploring its implications for everything from fundamental physics and cosmology to the origins of gold and other heavy elements.


    A small team of UC Santa Cruz astronomers were the first team to observe light from two neutron stars merging in August. The implications are huge.

    ALL THE GOLD IN THE UNIVERSE

    It turns out that the origins of the heaviest elements, such as gold, platinum, uranium—pretty much everything heavier than iron—has been an enduring conundrum. All the lighter elements have well-explained origins in the nuclear fusion reactions that make stars shine or in the explosions of stars (supernovae). Initially, astrophysicists thought supernovae could account for the heavy elements, too, but there have always been problems with that theory, says Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz.

    4
    The violent merger of two neutron stars is thought to involve three main energy-transfer processes, shown in this diagram, that give rise to the different types of radiation seen by astronomers, including a gamma-ray burst and a kilonova explosion seen in visible light. (Image credit: Murguia-Berthier et al., Science)

    A theoretical astrophysicist, Ramirez-Ruiz has been a leading proponent of the idea that neutron star mergers are the source of the heavy elements. Building a heavy atomic nucleus means adding a lot of neutrons to it. This process is called rapid neutron capture, or the r-process, and it requires some of the most extreme conditions in the universe: extreme temperatures, extreme densities, and a massive flow of neutrons. A neutron star merger fits the bill.

    Ramirez-Ruiz and other theoretical astrophysicists use supercomputers to simulate the physics of extreme events like supernovae and neutron star mergers. This work always goes hand in hand with observational astronomy. Theoretical predictions tell observers what signatures to look for to identify these events, and observations tell theorists if they got the physics right or if they need to tweak their models. The observations by Foley and others of the neutron star merger now known as SSS17a are giving theorists, for the first time, a full set of observational data to compare with their theoretical models.

    According to Ramirez-Ruiz, the observations support the theory that neutron star mergers can account for all the gold in the universe, as well as about half of all the other elements heavier than iron.

    RIPPLES IN THE FABRIC OF SPACE-TIME

    Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity, but until recently they were impossible to observe. LIGO’s extraordinarily sensitive detectors achieved the first direct detection of gravitational waves, from the collision of two black holes, in 2015. Gravitational waves are created by any massive accelerating object, but the strongest waves (and the only ones we have any chance of detecting) are produced by the most extreme phenomena.

    Two massive compact objects—such as black holes, neutron stars, or white dwarfs—orbiting around each other faster and faster as they draw closer together are just the kind of system that should radiate strong gravitational waves. Like ripples spreading in a pond, the waves get smaller as they spread outward from the source. By the time they reached Earth, the ripples detected by LIGO caused distortions of space-time thousands of times smaller than the nucleus of an atom.

    The rarefied signals recorded by LIGO’s detectors not only prove the existence of gravitational waves, they also provide crucial information about the events that produced them. Combined with the telescope observations of the neutron star merger, it’s an incredibly rich set of data.

    LIGO can tell scientists the masses of the merging objects and the mass of the new object created in the merger, which reveals whether the merger produced another neutron star or a more massive object that collapsed into a black hole. To calculate how much mass was ejected in the explosion, and how much mass was converted to energy, scientists also need the optical observations from telescopes. That’s especially important for quantifying the nucleosynthesis of heavy elements during the merger.

    LIGO can also provide a measure of the distance to the merging neutron stars, which can now be compared with the distance measurement based on the light from the merger. That’s important to cosmologists studying the expansion of the universe, because the two measurements are based on different fundamental forces (gravity and electromagnetism), giving completely independent results.

    “This is a huge step forward in astronomy,” Foley said. “Having done it once, we now know we can do it again, and it opens up a whole new world of what we call ‘multi-messenger’ astronomy, viewing the universe through different fundamental forces.”

    IN THIS REPORT

    Neutron stars
    A team from UC Santa Cruz was the first to observe the light from a neutron star merger that took place on August 17, 2017 and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)

    5
    Graduate students and post-doctoral scholars at UC Santa Cruz played key roles in the dramatic discovery and analysis of colliding neutron stars.Astronomer Ryan Foley leads a team of young graduate students and postdoctoral scholars who have pulled off an extraordinary coup. Following up on the detection of gravitational waves from the violent merger of two neutron stars, Foley’s team was the first to find the source with a telescope and take images of the light from this cataclysmic event. In so doing, they beat much larger and more senior teams with much more powerful telescopes at their disposal.

    “We’re sort of the scrappy young upstarts who worked hard and got the job done,” said Foley, an untenured assistant professor of astronomy and astrophysics at UC Santa Cruz.

    7
    David Coulter, graduate student

    The discovery on August 17, 2017, has been a scientific bonanza, yielding over 100 scientific papers from numerous teams investigating the new observations. Foley’s team is publishing seven papers, each of which has a graduate student or postdoc as the first author.

    “I think it speaks to Ryan’s generosity and how seriously he takes his role as a mentor that he is not putting himself front and center, but has gone out of his way to highlight the roles played by his students and postdocs,” said Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz and the most senior member of Foley’s team.

    “Our team is by far the youngest and most diverse of all of the teams involved in the follow-up observations of this neutron star merger,” Ramirez-Ruiz added.

    8
    Charles Kilpatrick, postdoctoral scholar

    Charles Kilpatrick, a 29-year-old postdoctoral scholar, was the first person in the world to see an image of the light from colliding neutron stars. He was sitting in an office at UC Santa Cruz, working with first-year graduate student Cesar Rojas-Bravo to process image data as it came in from the Swope Telescope in Chile. To see if the Swope images showed anything new, he had also downloaded “template” images taken in the past of the same galaxies the team was searching.

    9
    Ariadna Murguia-Berthier, graduate student

    “In one image I saw something there that was not in the template image,” Kilpatrick said. “It took me a while to realize the ramifications of what I was seeing. This opens up so much new science, it really marks the beginning of something that will continue to be studied for years down the road.”

    At the time, Foley and most of the others in his team were at a meeting in Copenhagen. When they found out about the gravitational wave detection, they quickly got together to plan their search strategy. From Copenhagen, the team sent instructions to the telescope operators in Chile telling them where to point the telescope. Graduate student David Coulter played a key role in prioritizing the galaxies they would search to find the source, and he is the first author of the discovery paper published in Science.

    10
    Matthew Siebert, graduate student

    “It’s still a little unreal when I think about what we’ve accomplished,” Coulter said. “For me, despite the euphoria of recognizing what we were seeing at the moment, we were all incredibly focused on the task at hand. Only afterward did the significance really sink in.”

    Just as Coulter finished writing his paper about the discovery, his wife went into labor, giving birth to a baby girl on September 30. “I was doing revisions to the paper at the hospital,” he said.

    It’s been a wild ride for the whole team, first in the rush to find the source, and then under pressure to quickly analyze the data and write up their findings for publication. “It was really an all-hands-on-deck moment when we all had to pull together and work quickly to exploit this opportunity,” said Kilpatrick, who is first author of a paper comparing the observations with theoretical models.

    11
    César Rojas Bravo, graduate student

    Graduate student Matthew Siebert led a paper analyzing the unusual properties of the light emitted by the merger. Astronomers have observed thousands of supernovae (exploding stars) and other “transients” that appear suddenly in the sky and then fade away, but never before have they observed anything that looks like this neutron star merger. Siebert’s paper concluded that there is only a one in 100,000 chance that the transient they observed is not related to the gravitational waves.

    Ariadna Murguia-Berthier, a graduate student working with Ramirez-Ruiz, is first author of a paper synthesizing data from a range of sources to provide a coherent theoretical framework for understanding the observations.

    Another aspect of the discovery of great interest to astronomers is the nature of the galaxy and the galactic environment in which the merger occurred. Postdoctoral scholar Yen-Chen Pan led a paper analyzing the properties of the host galaxy. Enia Xhakaj, a new graduate student who had just joined the group in August, got the opportunity to help with the analysis and be a coauthor on the paper.

    12
    Yen-Chen Pan, postdoctoral scholar

    “There are so many interesting things to learn from this,” Foley said. “It’s a great experience for all of us to be part of such an important discovery.”

    13
    Enia Xhakaj, graduate student

    IN THIS REPORT

    Scientific Papers from the 1M2H Collaboration

    Coulter et al., Science, Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source

    Drout et al., Science, Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis

    Shappee et al., Science, Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger

    Kilpatrick et al., Science, Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

    Siebert et al., ApJL, The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source

    Pan et al., ApJL, The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source

    Murguia-Berthier et al., ApJL, A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

    Kasen et al., Nature, Origin of the heavy elements in binary neutron star mergers from a gravitational wave event

    Abbott et al., Nature, A gravitational-wave standard siren measurement of the Hubble constant (The LIGO Scientific Collaboration and The Virgo Collaboration, The 1M2H Collaboration, The Dark Energy Camera GW-EM Collaboration and the DES Collaboration, The DLT40 Collaboration, The Las Cumbres Observatory Collaboration, The VINROUGE Collaboration & The MASTER Collaboration)

    Abbott et al., ApJL, Multi-messenger Observations of a Binary Neutron Star Merger

    PRESS RELEASES AND MEDIA COVERAGE


    Watch Ryan Foley tell the story of how his team found the neutron star merger in the video below. 2.5 HOURS.

    Press releases:

    UC Santa Cruz Press Release

    UC Berkeley Press Release

    Carnegie Institution of Science Press Release

    LIGO Collaboration Press Release

    National Science Foundation Press Release

    Media coverage:

    The Atlantic – The Slack Chat That Changed Astronomy

    Washington Post – Scientists detect gravitational waves from a new kind of nova, sparking a new era in astronomy

    New York Times – LIGO Detects Fierce Collision of Neutron Stars for the First Time

    Science – Merging neutron stars generate gravitational waves and a celestial light show

    CBS News – Gravitational waves – and light – seen in neutron star collision

    CBC News – Astronomers see source of gravitational waves for 1st time

    San Jose Mercury News – A bright light seen across the universe, proving Einstein right

    Popular Science – Gravitational waves just showed us something even cooler than black holes

    Scientific American – Gravitational Wave Astronomers Hit Mother Lode

    Nature – Colliding stars spark rush to solve cosmic mysteries

    National Geographic – In a First, Gravitational Waves Linked to Neutron Star Crash

    Associated Press – Astronomers witness huge cosmic crash, find origins of gold

    Science News – Neutron star collision showers the universe with a wealth of discoveries

    UCSC press release
    First observations of merging neutron stars mark a new era in astronomy

    Credits

    Writing: Tim Stephens
    Video: Nick Gonzales
    Photos: Carolyn Lagattuta
    Header image: Illustration by Robin Dienel courtesy of the Carnegie Institution for Science
    Design and development: Rob Knight
    Project managers: Sherry Main, Scott Hernandez-Jason, Tim Stephens

    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

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

    Noted in the video but not in the article:

    NASA/Chandra Telescope

    NASA/SWIFT Telescope

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    CTIO PROMPT telescope telescope built by the University of North Carolina at Chapel Hill at Cerro Tololo Inter-American Observatory in Chilein the Chilean Andes.

    PROMPT The six domes at CTIO in Chile.

    NASA NuSTAR X-ray telescope

    See the full article here .

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    Stem Education Coalition

    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

    Search for extraterrestrial intelligence expands at Lick Observatory
    New instrument scans the sky for pulses of infrared light
    March 23, 2015
    By Hilary Lebow
    1
    The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

    Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

    “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

    Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

    Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

    5
    UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch)

    Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

    “The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

    The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

    Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

    “We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

    Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

    “This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

    NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

    “Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

    NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

    The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

    UCSC is the home base for the Lick Observatory.

     
  • richardmitnick 7:51 pm on October 16, 2017 Permalink | Reply
    Tags: Astronomers proposed the existence of neutron stars in 1934, , , , , , , DES - Dark Energy Survey, , , Neutron stars have some of the strongest gravity you’ll find – black holes have the strongest, ,   

    From Stanford: “Stanford experts on LIGO’s binary neutron star milestone” 

    Stanford University Name
    Stanford University

    October 16, 2017
    Taylor Kubota
    (650) 724-7707
    tkubota@stanford.edu

    On August 17, 2017, the two detectors of Advanced LIGO, along with VIRGO, zeroed in on what appeared to be gravitational waves emanating from a pair of neutron stars spinning together – a long-held goal for the LIGO team.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    An alert went out to collaborators worldwide and within hours some 70 instruments turned their sites on the location a mere 310 million light-years away.

    2
    Artist’s rendering of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays that are shot out just seconds after the gravitational waves. Swirling clouds of material ejected from the merging stars glow with visible and other wavelengths of light. (Image credit: NSF/LIGO/Sonoma State University/A. Simonnet)

    Their combined observations, spanning the electromagnetic spectrum, confirm some of what physicists had theorized about this type of event and also open up new areas of research. Thousands of scientists contributed to this accomplishment, including many at Stanford University, and published the initial findings Oct. 16 in Physical Review Letters and The Astrophysical Journal Letters.

    [For science papers, see https://sciencesprings.wordpress.com/2017/10/16/from-hubble-nasa-missions-catch-first-light-from-a-gravitational-wave-event/ ]

    “It’s a frighteningly disordered, energetic place out there in the universe and gravitational waves added a new dimension to looking at it,” said Robert Byer, professor of applied physics at Stanford and member of LIGO who provided the laser for the initial detector. “For this event, that new dimension was complemented by the signals from the other electromagnetic wavelengths and all those together gave us a completely different view of what’s going on inside the neutron stars as they merged.”

    This observation and the others that are likely to follow could help further the understanding of General Relativity, the origins of elements heavier than iron, the evolution of stars and black holes, relativistic jets that squirt from black holes and neutron stars, and the Hubble constant, which is the cosmological parameter which determines the expansion rate of the universe.

    Stanford and LIGO

    LIGO is led by the Massachusetts Institute of Technology and the California Institute of Technology, but Stanford was brought into the collaboration in 1988, largely due to the ultra-clean, stable lasers developed by Byer. The Byer lab developed the chip for the laser in the initial LIGO detector, which they installed in the early 2000s and lasted the lifetime of the initial LIGO project, which concluded in 2010. Lasers for the Advanced LIGO built upon Byer’s earlier work, an effort led by Benno Wilkie of the Albert Einstein Institute Hannover, a former postdoctoral scholar in Stanford’s Ginzton lab.

    “We were looking for the problems that LIGO couldn’t actually worry about yet. We wanted to find those and solve them before they became roadblocks,” said Byer. “One thing that allowed Stanford to contribute to LIGO in these extraordinary ways is we have this long tradition of engineering and science working together – and that’s not common. Great credit also goes to our extraordinary graduate students who are the glue that hold it all together.”

    Daniel DeBra, professor emeritus of aeronautics and astronautics, designed the original platform for LIGO, a nested system so stable that, in the LIGO detection band, it moves no more than an atom relative to the movement of Earth’s surface. Another crucial element of the vibration isolation system is the silicate bonding technique used to suspend LIGO’s mirrors. As a visiting scholar at Stanford, Sheila Rowan of the University of Glasgow adapted this technique from previous work at Stanford on the Gravity Probe B telescope.

    The Dark Energy Camera (DECam), the instrument used by the Dark Energy Survey, was among the first cameras to see in optical light what the LIGO-VIRGO detectors observed in gravitational waves earlier that morning.

    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

    DECam imaged the entire area within which the object was expected to be and helped confirm that the event was a unique object – and very likely the event LIGO had seen earlier that day.

    Many people at Stanford and the SLAC National Accelerator Laboratory are part of the Dark Energy Survey team. Aaron Roodman, professor and chair of particle physics and astrophysics at SLAC, developed, commissioned and continues to optimize the Active Optics System of DECam.

    Looking to the future, DeBra and colleagues including Brian Lantz, a senior research scientist who leads the Engineering Test Facility for LIGO at Stanford, are improving signal detection of Advanced LIGO by damping the effects of vibrations on the optics.

    Other faculty are improving the sensitivity of the Fermi Large Area Telescope (LAT), a instrument helmed by Peter Michelson, a professor of physics, that can both confirm the existence of a binary neutron star system and rule out other possible sources. Its sister instrument on Fermi, the Gamma-Ray Burst Monitor, detected a gamma ray burst coming from the location given by LIGO and VIRGO 14 seconds after the gravitational wave signal.

    LIGO is offline for scheduled upgrades for the next year, but many of the researchers are already working on LIGO Voyager, the third-generation of LIGO, which is anticipated to increase the sensitivity by a factor of 2 and would lead to an estimated 800 percent increase in event rate.

    “This is only a beginning. There are many innovations to come and I don’t know where we’re going to be in 10 years, 20 years, 30 years,” said Michelson. “The window is open and there are going to be mind-blowing surprises. That, to me, is the most exciting.”

    What’s so special about neutron stars

    A neutron star results when the core of a large star collapses and the atoms get crushed. The protons and electrons squeeze together and the remaining star is about 95 percent neutrons. A tablespoon full of neutron stars weighs as much as Mt. Everest.

    “Neutron stars have some of the strongest gravity you’ll find – black holes have the strongest – and thus they give us handles on studying strong-field gravity around them to see if it deviates at all from General Relativity,” said Mandeep Gill, the outreach coordinator at KIPAC at SLAC and Stanford, and a member of the Dark Energy Survey collaboration.

    Astronomers proposed the existence of neutron stars in 1934. They were first found in 1967, and then in 1975 a radio telescope observed the first instance of a binary neutron star system. From that discovery, Roger Blandford, professor of physics at Stanford, and colleagues confirmed predictions of the General Theory of Relativity.

    Blandford said the calculations related to the system Advanced LIGO saw are even more complicated because the stars are much closer together and could only be completed by a computer. This observation continues to support the General Theory of Relativity but Gill is hopeful that additional binary neutron star systems may begin to inform extension to the theory that could reveal how it fits with quantum theory, dark energy and dark matter.

    “One of the things I find terribly exciting about these observations is that not only do they confirm aspects of astronomical and relativistic precepts but they actually teach us things about nuclear physics that we don’t properly understand,” said Blandford. “We certainly have many things that we’ve speculated about and thought about – and I have to believe that some of that will be right – but some of it will be much more interesting than what we could anticipate.”

    As we observe more of these systems, which scientists anticipate, we may finally understand long-standing mysteries of neutron stars, like whether they have earthquakes on their crust or if, as suspected, they have small mountains that send out their own gravitational wave signal.

    “Even though we’ve been doing astronomy since the dawn of civilization, every time we turn on new instruments, we learn new things about what’s going on in the universe,” said Lantz. “If the elements heavier than iron are actually made in events like this, that stuff is here on Earth and it’s likely that was generated by events like this. It gives you sort of a way to reach out and touch the stars.”

    Blandford is also KIPAC Division Director in the Particle Physics and Astrophysics Directorate and professor of particle physics and astrophysics at SLAC; Byer is also a professor in SLAC’s Photon Science Directorate.

    Additional Stanford contributors to the LIGO multi-messenger observation include Edgard Bonilla, Riccardo Bassiri, Elliot Bloom, David Burke, Robert Cameron, James Chiang, Carissa Cirelli, C.E. Cunha, Christopher Davis, Seth Digel, Mattia Di Mauro, Richard Dubois, Martin Fejer, Warren Focke, Thomas Glanzman, Daniel Gruen, Ashot Markosyan, Manuel Meyer, Igor Moskalenko, Nicola Omedai, Elena Orlando, Troy Porter, Anita Reimer, Olaf Reimer, Leon Rochester, Aaron Roodman, Eli Rykoff, Brett Shapiro, Rafe Schindler, Jana B. Thayer, John Gregg Thayer, Giacomo Vianello and Risa Wechsler.

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 1:24 pm on September 28, 2017 Permalink | Reply
    Tags: , “ExaSky” - “Computing the Sky at Extreme Scales” project or, Cartography of the cosmos, DES - Dark Energy Survey, , , , Salman Habib, , The computer can generate many universes with different parameters, There are hundreds of billions of stars in our own Milky Way galaxy   

    From ALCF: “Cartography of the cosmos” 

    Argonne Lab
    News from Argonne National Laboratory

    ALCF

    September 27, 2017
    John Spizzirri

    2
    Argonne’s Salman Habib leads the ExaSky project, which takes on the biggest questions, mysteries, and challenges currently confounding cosmologists.

    1
    No image caption or credit

    There are hundreds of billions of stars in our own Milky Way galaxy.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    Estimates indicate a similar number of galaxies in the observable universe, each with its own large assemblage of stars, many with their own planetary systems. Beyond and between these stars and galaxies are all manner of matter in various phases, such as gas and dust. Another form of matter, dark matter, exists in a very different and mysterious form, announcing its presence indirectly only through its gravitational effects.

    This is the universe Salman Habib is trying to reconstruct, structure by structure, using precise observations from telescope surveys combined with next-generation data analysis and simulation techniques currently being primed for exascale computing.

    “We’re simulating all the processes in the structure and formation of the universe. It’s like solving a very large physics puzzle,” said Habib, a senior physicist and computational scientist with the High Energy Physics and Mathematics and Computer Science divisions of the U.S. Department of Energy’s (DOE) Argonne National Laboratory.

    Habib leads the “Computing the Sky at Extreme Scales” project or “ExaSky,” one of the first projects funded by the recently established Exascale Computing Project (ECP), a collaborative effort between DOE’s Office of Science and its National Nuclear Security Administration.

    From determining the initial cause of primordial fluctuations to measuring the sum of all neutrino masses, this project’s science objectives represent a laundry list of the biggest questions, mysteries, and challenges currently confounding cosmologists.

    There is the question of dark energy, the potential cause of the accelerated expansion of the universe, while yet another is the nature and distribution of dark matter in the universe.

    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

    Dark Matter Research

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

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

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

    Dark Matter Particle Explorer China

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

    LUX Dark matter Experiment at SURF, Lead, SD, USA

    ADMX Axion Dark Matter Experiment, U Uashington

    These are immense questions that demand equally expansive computational power to answer. The ECP is readying science codes for exascale systems, the new workhorses of computational and big data science.

    Initiated to drive the development of an “exascale ecosystem” of cutting-edge, high-performance architectures, codes and frameworks, the ECP will allow researchers to tackle data and computationally intensive challenges such as the ExaSky simulations of the known universe.

    In addition to the magnitude of their computational demands, ECP projects are selected based on whether they meet specific strategic areas, ranging from energy and economic security to scientific discovery and healthcare.

    “Salman’s research certainly looks at important and fundamental scientific questions, but it has societal benefits, too,” said Paul Messina, Argonne Distinguished Fellow. “Human beings tend to wonder where they came from, and that curiosity is very deep.”

    HACC’ing the night sky

    For Habib, the ECP presents a two-fold challenge — how do you conduct cutting-edge science on cutting-edge machines?

    The cross-divisional Argonne team has been working on the science through a multi-year effort at the Argonne Leadership Computing Facility (ALCF), a DOE Office of Science User Facility. The team is running cosmological simulations for large-scale sky surveys on the facility’s 10-petaflop high-performance computer, Mira. The simulations are designed to work with observational data collected from specialized survey telescopes, like the forthcoming Dark Energy Spectroscopic Instrument (DESI) and the Large Synoptic Survey Telescope (LSST).

    LBNL/DESI Dark Energy Spectroscopic Instrument for the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory near Tucson, Ariz, USA

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction 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.

    Survey telescopes look at much larger areas of the sky — up to half the sky, at any point — than does the Hubble Space Telescope, for instance, which focuses more on individual objects.

    NASA/ESA Hubble Telescope

    One night concentrating on one patch, the next night another, survey instruments systematically examine the sky to develop a cartographic record of the cosmos, as Habib describes it.

    Working in partnership with Los Alamos and Lawrence Berkeley National Laboratories, the Argonne team is readying itself to chart the rest of the course.

    Their primary code, which Habib helped develop, is already among the fastest science production codes in use. Called HACC (Hardware/Hybrid Accelerated Cosmology Code), this particle-based cosmology framework supports a variety of programming models and algorithms.

    Unique among codes used in other exascale computing projects, it can run on all current and prototype architectures, from the basic X86 chip used in most home PCs, to graphics processing units, to the newest Knights Landing chip found in Theta, the ALCF’s latest supercomputing system.

    As robust as the code is already, the HACC team continues to develop it further, adding significant new capabilities, such as hydrodynamics and associated subgrid models.

    “When you run very large simulations of the universe, you can’t possibly do everything, because it’s just too detailed,” Habib explained. “For example, if we’re running a simulation where we literally have tens to hundreds of billions of galaxies, we cannot follow each galaxy in full detail. So we come up with approximate approaches, referred to as subgrid models.”

    Even with these improvements and its successes, the HACC code still will need to increase its performance and memory to be able to work in an exascale framework. In addition to HACC, the ExaSky project employs the adaptive mesh refinement code Nyx, developed at Lawrence Berkeley. HACC and Nyx complement each other with different areas of specialization. The synergy between the two is an important element of the ExaSky team’s approach.

    A cosmological simulation approach that melds multiple approaches allows the verification of difficult-to-resolve cosmological processes involving gravitational evolution, gas dynamics and astrophysical effects at very high dynamic ranges. New computational methods like machine learning will help scientists to quickly and systematically recognize features in both the observational and simulation data that represent unique events.

    A trillion particles of light

    The work produced under the ECP will serve several purposes, benefitting both the future of cosmological modeling and the development of successful exascale platforms.

    On the modeling end, the computer can generate many universes with different parameters, allowing researchers to compare their models with observations to determine which models fit the data most accurately. Alternatively, the models can make predictions for observations yet to be made.

    Models also can produce extremely realistic pictures of the sky, which is essential when planning large observational campaigns, such as those by DESI and LSST.

    “Before you spend the money to build a telescope, it’s important to also produce extremely good simulated data so that people can optimize observational campaigns to meet their data challenges,” said Habib.

    But the cost of realism is expensive. Simulations can range in the trillion-particle realm and produce several petabytes — quadrillions of bytes — of data in a single run. As exascale becomes prevalent, these simulations will produce 10 to 100 times as much data.

    The work that the ExaSky team is doing, along with that of the other ECP research teams, will help address these challenges and those faced by computer manufacturers and software developers as they create coherent, functional exascale platforms to meet the needs of large-scale science. By working with their own codes on pre-exascale machines, the ECP research team can help guide vendors in chip design, I/O bandwidth and memory requirements and other features.

    “All of these things can help the ECP community optimize their systems,” noted Habib. “That’s the fundamental reason why the ECP science teams were chosen. We will take the lessons we learn in dealing with this architecture back to the rest of the science community and say, ‘We have found a solution.’”

    The Exascale Computing Project is a collaborative effort of two DOE organizations — the Office of Science and the National Nuclear Security Administration. As part of President Obama’s National Strategic Computing initiative, ECP was established to develop a capable exascale ecosystem, encompassing applications, system software, hardware technologies and architectures and workforce development to meet the scientific and national security mission needs of DOE in the mid-2020s timeframe.

    ANL ALCF Cetus IBM supercomputer

    ANL ALCF Theta Cray supercomputer

    ANL ALCF Cray Aurora supercomputer

    ANL ALCF MIRA IBM Blue Gene Q supercomputer at the Argonne Leadership Computing Facility

    See the full article here .

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

    About ALCF

    The Argonne Leadership Computing Facility’s (ALCF) mission is to accelerate major scientific discoveries and engineering breakthroughs for humanity by designing and providing world-leading computing facilities in partnership with the computational science community.

    We help researchers solve some of the world’s largest and most complex problems with our unique combination of supercomputing resources and expertise.

    ALCF projects cover many scientific disciplines, ranging from chemistry and biology to physics and materials science. Examples include modeling and simulation efforts to:

    Discover new materials for batteries
    Predict the impacts of global climate change
    Unravel the origins of the universe
    Develop renewable energy technologies

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

    Argonne Lab Campus

     
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