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  • richardmitnick 1:37 pm on August 14, 2018 Permalink | Reply
    Tags: , , , Black oles and Dark Matter?, , DECam - built at FNAL, , ,   

    From Lawrence Livermore National Laboratory: “Quest for source of black hole dark matter” 

    From Lawrence Livermore National Laboratory

    Aug. 13, 2018
    Anne M Stark

    LLNL scientists Michael Schneider, Will Dawson, Nathan Golovich and George Chapline look for black holes in the Lab’s telescope remote observing room. Photo by Julie Russell/LLNL.

    Like a game of “hide and seek,” Lawrence Livermore astrophysicists know that there are black holes hiding in the Milky Way, just not where.

    If they find them toward the galactic bulge (a tightly packed group of stars) and the Magellanic Clouds, then black holes as massive as 10,000 times the mass of the sun might make up dark matter. If they are only toward the galactic bulge then they are probably just from a few dead stars.

    Typically to observe the Magellanic Clouds, scientists must travel to observatories in the Southern Hemisphere.

    Large Magellanic Cloud. Adrian Pingstone December 2003

    Small Magellanic Cloud. NASA/ESA Hubble and ESO/Digitized Sky Survey 2

    Magellanic Bridge ESA Gaia satellite. Image credit V. Belokurov D. Erkal A. Mellinger.

    But recently, the LLNL team got a new tool that’s a little closer to home to help them in the search. As part of the Space Science and Security Program and an LDRD project, LLNL has a new telescope remote observing room.

    The team is using the observing room to conduct a gravitational microlensing survey of the Milky Way and Magellanic Clouds in search of intermediate mass black holes (approximately 10 to 10,000 times the mass of the sun) that may make up the majority of dark matter.

    “The remote observing room enables us to control the National Optical Astronomers Observatory Blanco 4-meter telescope located in Chile at the Cerro Tololo Inter-American Observatory,” said LLNL principal investigator Will Dawson.

    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 team already has conducted its first observing run with the remote observing room.

    The visible universe is composed of approximately 70 percent dark energy, 25 percent dark matter and 5 percent normal matter. However, dark matter has remained a mystery since it was first postulated in 1933. The MACHO Survey, led by Lawrence Livermore in the 1990s, sought to test whether dark matter was composed of baryonic massive compact halo objects (MACHOs). The survey concluded that baryonic MACHOs smaller than 10 solar masses could not account for more than 40 percent of the total dark matter mass.

    Recently, the discovery of two merging black holes has renewed interest in MACHO dark matter composed of primordial black holes (formed in the early universe, before the first stars) with approximately 10 to 10,000 solar masses. This is an idea first proposed in 1975 by LLNL physicist and project co-investigator George Chapline. The most direct means of exploring this mass range is by searching for the gravitational microlensing signal in existing archival astronomical imaging and carrying out a next-generation microlensing survey with state-of-the-art wide-field optical imagers on telescopes 10 to 25 times more powerful than those used in the original MACHO surveys.

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    Microlensing is an astronomical effect predicted by Einstein’s general theory of relativity. According to Einstein, when the light emanating from a star passes very close to another massive object (e.g., black hole) on its way to an observer on Earth, the gravity of the intermediary massive object will slightly bend and focus the light rays from the source star, causing the lensed background star to appear brighter than it normally would.

    “We are developing a novel means of microlensing detection that will enable us to detect the parallactic microlensing signature associated with black holes in this mass range,” Dawson said. “We will detect and constrain the fraction of dark matter composed of intermediate mass black holes and measure their mass spectrum in the Milky Way.”

    While the scientists are currently using the Cerro Tololo Inter-American Observatory in the search, eventually they will achieve even more sensitivity in observing black holes when the Large Synoptic Survey Telescope, which LLNL has supported for the last two decades, comes online in 2022.


    LSST Camera, built at SLAC

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

    See the full article here .


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    LLNL Campus

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration
    Lawrence Livermore National Laboratory (LLNL) is an American federal research facility in Livermore, California, United States, founded by the University of California, Berkeley in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System. In 2012, the laboratory had the synthetic chemical element livermorium named after it.

    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.”[1] Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    The Laboratory is located on a one-square-mile (2.6 km2) site at the eastern edge of Livermore. It also operates a 7,000 acres (28 km2) remote experimental test site, called Site 300, situated about 15 miles (24 km) southeast of the main lab site. LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees.

    LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore, an offshoot of the existing UC Radiation Laboratory at Berkeley. It was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence,[2] director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility.

    The new laboratory was sited at a former naval air station of World War II. It was already home to several UC Radiation Laboratory projects that were too large for its location in the Berkeley Hills above the UC campus, including one of the first experiments in the magnetic approach to confined thermonuclear reactions (i.e. fusion). About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than an urban university campus.

    Lawrence tapped 32-year-old Herbert York, a former graduate student of his, to run Livermore. Under York, the Lab had four main programs: Project Sherwood (the magnetic-fusion program), Project Whitney (the weapons-design program), diagnostic weapon experiments (both for the Los Alamos and Livermore laboratories), and a basic physics program. York and the new lab embraced the Lawrence “big science” approach, tackling challenging projects with physicists, chemists, engineers, and computational scientists working together in multidisciplinary teams. Lawrence died in August 1958 and shortly after, the university’s board of regents named both laboratories for him, as the Lawrence Radiation Laboratory.

    Historically, the Berkeley and Livermore laboratories have had very close relationships on research projects, business operations, and staff. The Livermore Lab was established initially as a branch of the Berkeley laboratory. The Livermore lab was not officially severed administratively from the Berkeley lab until 1971. To this day, in official planning documents and records, Lawrence Berkeley National Laboratory is designated as Site 100, Lawrence Livermore National Lab as Site 200, and LLNL’s remote test location as Site 300.[3]

    The laboratory was renamed Lawrence Livermore Laboratory (LLL) in 1971. On October 1, 2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the synthetic chemical element livermorium named after it. The LLNS takeover of the laboratory has been controversial. In May 2013, an Alameda County jury awarded over $2.7 million to five former laboratory employees who were among 430 employees LLNS laid off during 2008.[4] The jury found that LLNS breached a contractual obligation to terminate the employees only for “reasonable cause.”[5] The five plaintiffs also have pending age discrimination claims against LLNS, which will be heard by a different jury in a separate trial.[6] There are 125 co-plaintiffs awaiting trial on similar claims against LLNS.[7] The May 2008 layoff was the first layoff at the laboratory in nearly 40 years.[6]

    On March 14, 2011, the City of Livermore officially expanded the city’s boundaries to annex LLNL and move it within the city limits. The unanimous vote by the Livermore city council expanded Livermore’s southeastern boundaries to cover 15 land parcels covering 1,057 acres (4.28 km2) that comprise the LLNL site. The site was formerly an unincorporated area of Alameda County. The LLNL campus continues to be owned by the federal government.


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  • richardmitnick 2:36 pm on November 14, 2017 Permalink | Reply
    Tags: DECam - built at FNAL, DECaPS, , , 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

    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.

    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).


    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 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.

  • richardmitnick 7:51 pm on October 16, 2017 Permalink | Reply
    Tags: Astronomers proposed the existence of neutron stars in 1934, , , , , , DECam - built at FNAL, , , , 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

    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

    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.

    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 11:27 am on July 29, 2017 Permalink | Reply
    Tags: , , , , , , DECam - built at FNAL   

    From ASU: “ASU astronomers find young galaxies that appeared soon after the Big Bang” 

    ASU Bloc



    Using powerful Dark Energy Camera in Chile, researchers reach the cosmic dawn.

    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

    ASU astronomers Sangeeta Malhotra and James Rhoads, working with international teams in Chile and China, have discovered 23 young galaxies, seen as they were 800 million years after the Big Bang. The results from this sample have been recently published in The Astrophysical Journal.

    False color image of a 2 square degree region of the LAGER survey field, created from images taken in the optical at 500 nm (blue), in the near-infrared at 920 nm (red), and in a narrow-band filter centered at 964 nm (green). The small white boxes indicate the positions of the 23 LAEs discovered in the survey. The detailed insets (yellow) show two of the brightest LAEs. Credit Zhenya Zheng (SHAO) & Junxian Wang (USTC).

    Long ago, about 300,000 years after the beginning of the universe (the Big Bang), the universe was dark. There were no stars or galaxies, and the universe was filled with neutral hydrogen gas. In the next half-billion years or so, the first galaxies and stars appeared. Their energetic radiation ionized their surroundings, illuminating and transforming the universe.

    This dramatic transformation, known as re-ionization, occurred sometime in the interval between 300 million years and 1 billion years after the Big Bang. Astronomers are trying to pinpoint this milestone more precisely, and the galaxies found in this study help in this determination.

    “Before re-ionization, these galaxies were very hard to see, because their light is scattered by gas between galaxies, like a car’s headlights in fog,” Malhotra said. “As enough galaxies turn on and ‘burn off the fog’ they become easier to see. By doing so, they help provide a diagnostic to see how much of the ‘fog’ remains at any time in the early universe.”

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

    The galaxy search using the ASU-designed filter and DECam is part of the ongoing “Lyman Alpha Galaxies in the Epoch of Reionization” project (LAGER). It is the largest uniformly selected sample that goes far enough back in the history of the universe to reach cosmic dawn.

    “The combination of large survey size and sensitivity of this survey enables us to study galaxies that are common but faint, as well as those that are bright but rare, at this early stage in the universe,” said Malhotra.

    Junxian Wang, a co-author on this study and the lead of the Chinese LAGER team, adds that “our findings in this survey imply that a large fraction of the first galaxies that ionized and illuminated the universe formed early, less than 800 million years after the Big Bang.”

    The next steps for the team will be to build on these results. They plan to continue to search for distant star-forming galaxies over a larger volume of the universe and to further investigate the nature of some of the first galaxies in the universe.

    See the full article here .

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    ASU is the largest public university by enrollment in the United States.[11] Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College.[12][13][14] A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.[15]

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs.[16] ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

    ASU Tempe Campus
    ASU Tempe Campus

  • richardmitnick 4:07 pm on February 8, 2017 Permalink | Reply
    Tags: , , DECam - built at FNAL, Lambda-The Cosmological Constant, What is Dark Energy?   

    From the Dark Energy Survey: “Science” A Monster of an Article and a Must Read 

    Dark Energy Icon

    The Dark Energy Survey

    No writer credit

    Today marks the 100th anniversary of Einstein’s cosmological constant! Read more about how his “biggest blunder” may actually explain dark energy in the following article.

    The accelerated expansion of the universe is thought to be caused by a new phenomenon, dark energy, or perhaps requires a modification in our theory of gravity. We know little about the fundamental nature of dark energy: is it constant, or does it change in time? DES will observe thousands of supernovae and hundreds of millions of galaxies to measure or constrain changes in dark energy over cosmic time.

    The Universe is getting away from us

    For over 13 billion years, the universe has been expanding. The earliest evidence for expansion came from the work of Edwin Hubble, Vesto Slipher, and others in the 1920’s, who studied the distances to and the motions of galaxies a few million light-years distant. They found that the farther away galaxies are, the faster they recede from us, with recession speed proportional to distance. This Hubble Law of recession is universal: all galaxies across the universe are speeding away from each other with speed proportional to distance; that is, the universe is expanding.

    The expansion can be visualized by imagining a rubber sheet with a square grid imprinted on it, with galaxies occupying points on the grid. As the sheet stretches with the expansion, the size of the grid squares grows. As a result, any two points fixed on the grid move away from each other with a relative speed that’s proportional to the distance between them. With time, there is more and more space between the galaxies.

    Another visualization is presented in Figure 1, which shows the entire history of the universe, from the moment of the Big Bang (left) to today (right): when we look out at the universe, we look (leftward) into its past. The vertical size of the cone provides a scale for relative size of the observable universe from our vantage point on the right.

    Figure 1: Timeline of the cosmos; Photo credit: NASA/WMAP Science Team

    While cosmic expansion increases the distances between galaxies, they and their constituents still feel gravitational attraction: they are pulled toward each other whilst the expansion takes place. Galaxies and groups of galaxies can therefore remain gravitationally bound objects despite the overall expansion. Figure 1 also shows how stars, gas, dust, and dark matter eventually agglomerated into galaxies and galaxies into larger structures of the cosmic web (see Figure 3, which should be renamed Fig. 4).

    Figure 2: The fabric of space-time is warped by any object with mass; the greater the mass, the larger the resulting curvature of space-time. No image credit.

    In the early 20th century, Albert Einstein set the stage for modern cosmology by formulating his theory of gravity, General Relativity: curved space-time tells mass and energy (including light and particles of matter) how to move, while mass and energy tell space-time how to curve. This means that any thing that has mass (or energy) will warp space-time, even if slightly; and, in turn, that warped space-time will change the trajectories of particles traveling through it.

    Applied to the universe as a whole, Einstein’s theory relates the rate of cosmic expansion to the mass-energy of all the stuff in the universe. Since galaxies feel the gravitational tug of their neighbors, we would expect them to slow down over time: the expansion should be decelerating. If there were enough matter in the universe, the curvature of space-time would be strong enough to eventually reverse the expansion, leading to a big crunch in which everything collapses to an infinitely dense point. Throughout the 20th century, cosmologists attempted to measure the density of matter in the universe and the rate of slowing of the expansion, in order to answer the question of whether the universe would expand forever or recollapse.

    This picture changed in 1998, with the discovery by two teams of astronomers studying distant supernovae–exploding stars–that the expansion is not slowing down but speeding up. A particular kind of supernova, called a type Ia, reaches its maximum brightness (comparable to the brightness of an entire galaxy) two to three weeks after exploding and then fades over a few months. Type Ia supernovae have the remarkable property that, after accounting for differences in their colors and the rates at which they fade, they all have nearly the same intrinsic maximum brightness. For such “standardizable candles”, measuring how bright they appear to us tells us how far away they are and thus roughly how long it has taken their light to reach us. The two teams of astronomers found that supernovae that exploded when the universe was about two-thirds its present size appeared about 25% fainter than would be expected if the expansion were decelerating (see Fig. 4). This discovery of cosmic acceleration was awarded the Nobel Prize in physics in 2011.

    Figure 3: Supernova Hubble Diagram shows brightnesses of supernovae (vertical axis) vs. the size of the universe (horizontal axis). The blue region shows universes that accelerate, and the pink region shows universes in which the expansion slows down. The supernovae measured in the late 1990’s were fainter (and thus farther away) than expected for a universe that is decelerating, i.e., without dark energy. No image credit.

    Since ordinary matter would cause the expansion to slow down, cosmic acceleration requires us to posit a new, unseen form of energy in the universe–now called dark energy–that would have the strange property of giving rise to gravitational repulsion instead of attraction. Our picture is that, for much of cosmic history, matter dominated over dark energy and the expansion indeed slowed, enabling galaxies and large-scale structures to form as indicated above in Fig. 1. But several billion years ago, matter became sufficiently dilute due to expansion that dark energy became the dominant component of the universe, and the expansion hit the gas pedal.

    Around the turn of the millennium, this picture was bolstered by maps of the large-scale spatial distribution of galaxies, as shown in Fig. 4, and observations of the Cosmic Microwave Background (CMB) radiation.

    CMB per ESA/Planck
    CMB per ESA/Planck

    The CMB measurements showed that the spatial geometry of the universe is flat or Euclidean–two light rays emitted in parallel will always remain parallel, which is not the case if the geometry is curved–and this determines the total energy density of the universe. By contrast, the galaxy maps indicated that the density of matter in the universe is only about 30% of this total, so there must be another, unseen component that makes up the remaining 70%. That deficit fits perfectly with how much dark energy should be there according to the supernova observations.

    Figure 4: Two-dimensional map of the large-scale galaxy distribution observed by the Sloan Digital Sky Survey (SDSS). The Milky Way (our galaxy) is at the center. Regions with redder color have a higher density of galaxies; regions of a greener color have lower galaxy densities, and black regions have no galaxies. The filamentary structure evident in the map is known as the “cosmic web.” Image Credit: Sloan Digital Sky Survey

    SDSS Telescope at Apache Point Observatory, NM, USA
    SDSS Telescope at Apache Point Observatory, NM, USA

    Figure 5: Cosmic Energy Budget; Image Credit: Wikipedia

    Most of the mass in the universe comes from “dark matter,” which does not interact directly with light; dark matter interacts through gravity and at most weakly with other particles. The total cosmic energy budget is made up of about 25% dark matter, 5% “baryonic” or “ordinary” matter that is made of atoms, and about 70% dark energy (see Figure 5).

    We don’t yet know what makes up most of the energy in the universe. This makes dark energy one of the greatest mysteries in cosmology (perhaps all of science) as well as the focus of many experiments and surveys, possibly for years to come.

    Figure 6: The cosmological constant, “lambda.”

    What might dark energy be?

    One explanation is that dark energy is the intrinsic energy of empty space or of the vacuum. Scientists often refer to this as the “cosmological constant” — represented by the Greek letter, Λ (“lambda”), which is the same constant proposed by Einstein a century ago! In this theory, the vacuum energy behaves as a source of negative pressure that accelerates cosmic expansion. The vacuum energy would be constant throughout space and time.

    However, what if the density of dark energy changes over time? This is the question that many modern cosmology experiments and surveys, such as DES, are working to answer.

    One possibility for dark energy that changes in time is a new field that permeates the universe and that is in essence a much, much lighter cousin of the Higgs boson discovered in 2012 (this idea is sometimes dubbed “quintessence”). In these models, the density of dark energy would be slowly decreasing with time. A more exotic possibility would be if the density of dark energy grows over time; this would eventually result in a “Big Rip,” in which the gravitational repulsion of dark energy would grow so strong as to rip apart galaxies, stars and even atoms (see Figure 7).

    Figure 7: The consequences of different dark energy models. Where does this come from? Image credit: NASA

    How is DES suited for this study, and the probes?

    Dark Energy Camera [DECam],  built at FNAL
    Dark Energy Camera [DECam], built at FNAL

    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile
    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile

    The Dark Energy Survey is using four probes, all observed with a single instrument, to study cosmic acceleration with unprecedented accuracy and precision.

    The late 20th century gave us the era of ‘precision’ cosmology, in which we sought larger numbers of celestial objects (stars, galaxies, supernovae, etc.) for our measurements and analysis. The 21st century is now bringing the era of ‘accurate’ cosmology, in which our measurements are becoming increasingly exact. That is, we are performing our observations and analyses with greater and greater specificity, reducing the effect of systematic (measurement) uncertainties on our measurements.

    To learn that dark energy existed, we measured the structures within the universe (e.g., galaxies and galaxy clusters), the geometry of the universe (e.g., the Cosmic Microwave Background) and the expansion rate of the universe (with supernovae). In the Dark Energy Survey, we measure different versions of all of these phenomena.

    DES will use four probes of these phenomena to measure the effects of dark energy on the expansion history of the universe and on the growth of structure. We will observe thousands of supernovae, more than any other single survey in history: this reveals the expansion history of the universe. Using weak gravitational lensing and galaxy clusters, we will learn about the formation of structure and the amount of matter in the universe. Finally, we measure the distribution of galaxies across the cosmos through a technique called Baryon Acoustic Oscillations (BAO): this is similar to the measurements made of cosmic geometry with the CMB, but DES will use galaxies.

    © 2017 The Dark Energy Survey

    See the full article here .

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    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. 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.

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