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  • richardmitnick 11:58 am on September 28, 2021 Permalink | Reply
    Tags: "The Galactic Center Seen in Very High Energy Gamma Ray Light", , VERITAS-the Very Energetic Radiation Imaging Telescope Array System, Čerenkov Telescope Array   

    From Harvard-Smithsonian Center for Astrophysics (US): “The Galactic Center Seen in Very High Energy Gamma Ray Light” 

    From Harvard-Smithsonian Center for Astrophysics (US)

    8.13.21

    1

    VERITAS-the Very Energetic Radiation Imaging Telescope Array System, produced this pseudo-image of the Milky Way’ central region in high energy gamma rays. The image is a diagram showing, for each location, the statistical significance of the gamma-ray detection (not strictly the intensity of the light); the most reliable detection, at the bright central spot, has a statistical significance of 38 standard deviations. The image, spanning about one thousand light-years, shows six significant sources as well as extended emission. The results are consistent with the high energy gamma-ray emission being produced by supernovae and their remnants. Credit: VERITAS, and Adams et al. 2021.

    University of Arizona Veritas Four Čerenkov telescopes A novel gamma ray telescope under construction at The Fred Lawrence Whipple Observatory Smithsonian Astrophysical Observatory-Center for Astrophysics (US), Mount Hopkins, Arizona (US), altitude 2,606 m 8,550 ft. VERITAS is supported by grants from The National Science Foundation (US) and The Smithsonian Institution (US), by NSERC – Natural Sciences and Engineering Research Council of Canada [Conseil de recherches en sciences naturelles et en génie du Canada](CA), and by The Helmholtz Association of German Research Centres [Helmholtz-Gemeinschaft Deutscher Forschungszentren] (DE). This research uses resources provided by the Open Science Grid, which is supported by The National Science Foundation (US) and The Department of Energy (US)’s Office of Science, and resources of The DOE’s NERSC National Energy Research Scientific Computing Center (US), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and at the collaborating institutions in the construction and operation of the instrument.

    A large project known as the Čerenkov Telescope Array, composed of hundreds of similar telescopes to be situated at Roque de los Muchachos Observatory [Instituto de Astrofísica de Canarias ](ES) in the Canary Islands and Chile at European Southern Observatory Cerro Paranal(EU) site. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison (US) and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev.

    Over the past two decades, very high energy gamma ray emission has been detected coming from the direction of the Milky Way’s Galactic Center. The Galactic Center hosts many potential sites of particle acceleration including the supermassive black hole Sagittarius A* and remnants of supernova activity spread throughout the region. Electrons, protons, or other particles that are accelerated to speeds close to the speed of light will emit very high energy light – gamma rays – via a range of physical processes that depend on the particle types and the environmental conditions. Each gamma ray packs approximately one hundred million times the energy of the highest energy X-ray photon seen by the Chandra X-ray Observatory. The gamma-ray maps of the region show emission coming from one bright spot near the central supermassive black hole, from several other locations scattered within the central five hundred light-years, as well as a diffuse glow between them. However the limited spatial resolution of the detection facilities made it difficult to pinpoint the precise source(s) of the gamma rays. Astronomers have been working to refine the observations in order to identify the objects and constrain the mechanisms responsible for generating the gamma rays.

    CfA astronomers Wystan Benbow, Michael Daniel, Gareth Hughes, and Emmet Roache with a large team of their colleagues reanalyzed eight years of VERITAS observations of the Galactic Center region using advanced data reduction algorithms. The team finds that the bright central gamma-ray source is centered on the supermassive black hole (in agreement with some earlier studies) but also cannot exclude some neighboring structures as possible origins. Spectral information, however, implies that electrons are the dominant particles, in turn suggesting that supernova remnant activity with high magnetic fields could be powering the emission, not SgrA*. The absence of detected variability in the source is consistent with this model. The astronomers’ analysis of the diffuse radiation within the whole region finds that all the energy in that radiation could have been supplied by a single large supernova event in the past, but it is also consistent with the presence of a population of 10-100 thousand pulsars (themselves remnants of supernovae). CfA scientists are leading the development of a next-generation gamma-ray facility that will be able to make stronger source correspondences and also extend the range of detectable gamma-rays.

    Science paper:
    The Astrophysical Journal

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

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

    Founded in 1973 and headquartered in Cambridge, Massachusetts, the CfA leads a broad program of research in astronomy, astrophysics, Earth and space sciences, as well as science education. The CfA either leads or participates in the development and operations of more than fifteen ground- and space-based astronomical research observatories across the electromagnetic spectrum, including the forthcoming Giant Magellan Telescope(CL) and the Chandra X-ray Observatory(US), one of NASA’s Great Observatories.

    GMT Giant Magellan Telescope(CL) 21 meters, to be at the Carnegie Institution for Science’s(US) NSF (US) NOIRLab(US) NOAO(US) Las Campanas Observatory(CL) some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.

    Hosting more than 850 scientists, engineers, and support staff, the CfA is among the largest astronomical research institutes in the world. Its projects have included Nobel Prize-winning advances in cosmology and high energy astrophysics, the discovery of many exoplanets, and the first image of a black hole. The CfA also serves a major role in the global astrophysics research community: the CfA’s Astrophysics Data System(ADS)(US), for example, has been universally adopted as the world’s online database of astronomy and physics papers. Known for most of its history as the “Harvard-Smithsonian Center for Astrophysics”, the CfA rebranded in 2018 to its current name in an effort to reflect its unique status as a joint collaboration between Harvard University and the Smithsonian Institution. The CfA’s current Director (since 2004) is Charles R. Alcock, who succeeds Irwin I. Shapiro (Director from 1982 to 2004) and George B. Field (Director from 1973 to 1982).

    The Center for Astrophysics | Harvard & Smithsonian is not formally an independent legal organization, but rather an institutional entity operated under a Memorandum of Understanding between Harvard University and the Smithsonian Institution. This collaboration was formalized on July 1, 1973, with the goal of coordinating the related research activities of the Harvard College Observatory (HCO) and the Smithsonian Astrophysical Observatory (SAO) under the leadership of a single Director, and housed within the same complex of buildings on the Harvard campus in Cambridge, Massachusetts. The CfA’s history is therefore also that of the two fully independent organizations that comprise it. With a combined lifetime of more than 300 years, HCO and SAO have been host to major milestones in astronomical history that predate the CfA’s founding.

    History of the Smithsonian Astrophysical Observatory (SAO)

    Samuel Pierpont Langley, the third Secretary of the Smithsonian, founded the Smithsonian Astrophysical Observatory on the south yard of the Smithsonian Castle (on the U.S. National Mall) on March 1,1890. The Astrophysical Observatory’s initial, primary purpose was to “record the amount and character of the Sun’s heat”. Charles Greeley Abbot was named SAO’s first director, and the observatory operated solar telescopes to take daily measurements of the Sun’s intensity in different regions of the optical electromagnetic spectrum. In doing so, the observatory enabled Abbot to make critical refinements to the Solar constant, as well as to serendipitously discover Solar variability. It is likely that SAO’s early history as a solar observatory was part of the inspiration behind the Smithsonian’s “sunburst” logo, designed in 1965 by Crimilda Pontes.

    In 1955, the scientific headquarters of SAO moved from Washington, D.C. to Cambridge, Massachusetts to affiliate with the Harvard College Observatory (HCO). Fred Lawrence Whipple, then the chairman of the Harvard Astronomy Department, was named the new director of SAO. The collaborative relationship between SAO and HCO therefore predates the official creation of the CfA by 18 years. SAO’s move to Harvard’s campus also resulted in a rapid expansion of its research program. Following the launch of Sputnik (the world’s first human-made satellite) in 1957, SAO accepted a national challenge to create a worldwide satellite-tracking network, collaborating with the United States Air Force on Project Space Track.

    With the creation of National Aeronautics and Space Administration(US) the following year and throughout the space race, SAO led major efforts in the development of orbiting observatories and large ground-based telescopes, laboratory and theoretical astrophysics, as well as the application of computers to astrophysical problems.

    History of Harvard College Observatory (HCO)

    Partly in response to renewed public interest in astronomy following the 1835 return of Halley’s Comet, the Harvard College Observatory was founded in 1839, when the Harvard Corporation appointed William Cranch Bond as an “Astronomical Observer to the University”. For its first four years of operation, the observatory was situated at the Dana-Palmer House (where Bond also resided) near Harvard Yard, and consisted of little more than three small telescopes and an astronomical clock. In his 1840 book recounting the history of the college, then Harvard President Josiah Quincy III noted that “…there is wanted a reflecting telescope equatorially mounted…”. This telescope, the 15-inch “Great Refractor”, opened seven years later (in 1847) at the top of Observatory Hill in Cambridge (where it still exists today, housed in the oldest of the CfA’s complex of buildings). The telescope was the largest in the United States from 1847 until 1867. William Bond and pioneer photographer John Adams Whipple used the Great Refractor to produce the first clear Daguerrotypes of the Moon (winning them an award at the 1851 Great Exhibition in London). Bond and his son, George Phillips Bond (the second Director of HCO), used it to discover Saturn’s 8th moon, Hyperion (which was also independently discovered by William Lassell).

    Under the directorship of Edward Charles Pickering from 1877 to 1919, the observatory became the world’s major producer of stellar spectra and magnitudes, established an observing station in Peru, and applied mass-production methods to the analysis of data. It was during this time that HCO became host to a series of major discoveries in astronomical history, powered by the Observatory’s so-called “Computers” (women hired by Pickering as skilled workers to process astronomical data). These “Computers” included Williamina Fleming; Annie Jump Cannon; Henrietta Swan Leavitt; Florence Cushman; and Antonia Maury, all widely recognized today as major figures in scientific history. Henrietta Swan Leavitt, for example, discovered the so-called period-luminosity relation for Classical Cepheid variable stars, establishing the first major “standard candle” with which to measure the distance to galaxies. Now called “Leavitt’s Law”, the discovery is regarded as one of the most foundational and important in the history of astronomy; astronomers like Edwin Hubble, for example, would later use Leavitt’s Law to establish that the Universe is expanding, the primary piece of evidence for the Big Bang model.

    Upon Pickering’s retirement in 1921, the Directorship of HCO fell to Harlow Shapley (a major participant in the so-called “Great Debate” of 1920). This era of the observatory was made famous by the work of Cecelia Payne-Gaposchkin, who became the first woman to earn a Ph.D. in astronomy from Radcliffe College (a short walk from the Observatory). Payne-Gapochkin’s 1925 thesis proposed that stars were composed primarily of hydrogen and helium, an idea thought ridiculous at the time. Between Shapley’s tenure and the formation of the CfA, the observatory was directed by Donald H. Menzel and then Leo Goldberg, both of whom maintained widely recognized programs in solar and stellar astrophysics. Menzel played a major role in encouraging the Smithsonian Astrophysical Observatory to move to Cambridge and collaborate more closely with HCO.

    Joint history as the Center for Astrophysics (CfA)

    The collaborative foundation for what would ultimately give rise to the Center for Astrophysics began with SAO’s move to Cambridge in 1955. Fred Whipple, who was already chair of the Harvard Astronomy Department (housed within HCO since 1931), was named SAO’s new director at the start of this new era; an early test of the model for a unified Directorship across HCO and SAO. The following 18 years would see the two independent entities merge ever closer together, operating effectively (but informally) as one large research center.

    This joint relationship was formalized as the new Harvard–Smithsonian Center for Astrophysics on July 1, 1973. George B. Field, then affiliated with UC Berkeley(US), was appointed as its first Director. That same year, a new astronomical journal, the CfA Preprint Series was created, and a CfA/SAO instrument flying aboard Skylab discovered coronal holes on the Sun. The founding of the CfA also coincided with the birth of X-ray astronomy as a new, major field that was largely dominated by CfA scientists in its early years. Riccardo Giacconi, regarded as the “father of X-ray astronomy”, founded the High Energy Astrophysics Division within the new CfA by moving most of his research group (then at American Sciences and Engineering) to SAO in 1973. That group would later go on to launch the Einstein Observatory (the first imaging X-ray telescope) in 1976, and ultimately lead the proposals and development of what would become the Chandra X-ray Observatory. Chandra, the second of NASA’s Great Observatories and still the most powerful X-ray telescope in history, continues operations today as part of the CfA’s Chandra X-ray Center. Giacconi would later win the 2002 Nobel Prize in Physics for his foundational work in X-ray astronomy.

    Shortly after the launch of the Einstein Observatory, the CfA’s Steven Weinberg won the 1979 Nobel Prize in Physics for his work on electroweak unification. The following decade saw the start of the landmark CfA Redshift Survey (the first attempt to map the large scale structure of the Universe), as well as the release of the Field Report, a highly influential Astronomy & Astrophysics Decadal Survey chaired by the outgoing CfA Director George Field. He would be replaced in 1982 by Irwin Shapiro, who during his tenure as Director (1982 to 2004) oversaw the expansion of the CfA’s observing facilities around the world.

    CfA-led discoveries throughout this period include canonical work on Supernova 1987A, the “CfA2 Great Wall” (then the largest known coherent structure in the Universe), the best-yet evidence for supermassive black holes, and the first convincing evidence for an extrasolar planet.

    The 1990s also saw the CfA unwittingly play a major role in the history of computer science and the internet: in 1990, SAO developed SAOImage, one of the world’s first X11-based applications made publicly available (its successor, DS9, remains the most widely used astronomical FITS image viewer worldwide). During this time, scientists at the CfA also began work on what would become the Astrophysics Data System (ADS), one of the world’s first online databases of research papers. By 1993, the ADS was running the first routine transatlantic queries between databases, a foundational aspect of the internet today.

    The CfA Today

    Research at the CfA

    Charles Alcock, known for a number of major works related to massive compact halo objects, was named the third director of the CfA in 2004. Today Alcock overseas one of the largest and most productive astronomical institutes in the world, with more than 850 staff and an annual budget in excess of $100M. The Harvard Department of Astronomy, housed within the CfA, maintains a continual complement of approximately 60 Ph.D. students, more than 100 postdoctoral researchers, and roughly 25 undergraduate majors in astronomy and astrophysics from Harvard College. SAO, meanwhile, hosts a long-running and highly rated REU Summer Intern program as well as many visiting graduate students. The CfA estimates that roughly 10% of the professional astrophysics community in the United States spent at least a portion of their career or education there.

    The CfA is either a lead or major partner in the operations of the Fred Lawrence Whipple Observatory, the Submillimeter Array, MMT Observatory, the South Pole Telescope, VERITAS, and a number of other smaller ground-based telescopes. The CfA’s 2019-2024 Strategic Plan includes the construction of the Giant Magellan Telescope as a driving priority for the Center.

    CFA Harvard Smithsonian Submillimeter Array on MaunaKea, Hawaii, USA, Altitude 4,205 m (13,796 ft).

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

    Along with the Chandra X-ray Observatory, the CfA plays a central role in a number of space-based observing facilities, including the recently launched Parker Solar Probe, Kepler Space Telescope, the Solar Dynamics Observatory (SDO), and HINODE. The CfA, via the Smithsonian Astrophysical Observatory, recently played a major role in the Lynx X-ray Observatory, a NASA-Funded Large Mission Concept Study commissioned as part of the 2020 Decadal Survey on Astronomy and Astrophysics (“Astro2020”). If launched, Lynx would be the most powerful X-ray observatory constructed to date, enabling order-of-magnitude advances in capability over Chandra.

    NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker.

    SAO is one of the 13 stakeholder institutes for the Event Horizon Telescope Board, and the CfA hosts its Array Operations Center. In 2019, the project revealed the first direct image of a black hole.

    The result is widely regarded as a triumph not only of observational radio astronomy, but of its intersection with theoretical astrophysics. Union of the observational and theoretical subfields of astrophysics has been a major focus of the CfA since its founding.

    In 2018, the CfA rebranded, changing its official name to the “Center for Astrophysics | Harvard & Smithsonian” in an effort to reflect its unique status as a joint collaboration between Harvard University and the Smithsonian Institution. Today, the CfA receives roughly 70% of its funding from NASA, 22% from Smithsonian federal funds, and 4% from the National Science Foundation. The remaining 4% comes from contributors including the United States Department of Energy, the Annenberg Foundation, as well as other gifts and endowments.

     
  • richardmitnick 5:21 pm on August 25, 2020 Permalink | Reply
    Tags: , , , , , , , Čerenkov Telescope Array   

    From Symmetry: “A bit of MAGIC” 

    Symmetry Mag
    From Symmetry<

    08/25/20
    Liz Kruesi

    The MAGIC telescope’s first observation of a gamma-ray burst gave astronomers surprising new insight into the phenomenon.

    MAGIC Čerenkov telescopes at the Observatorio del Roque de los Muchachos (Garfia, La Palma, Spain)), Altitude 2,396 m (7,861 ft)

    Elena Moretti was filling out paperwork in her room at the astronomer dormitories at the Canary Islands’ Roque de los Muchachos Observatory when, just before 9 p.m., her phone rang. On the line was Moretti’s colleague Cosimo Nigro, who was at the control room of the Major Atmospheric Gamma Imaging Čerenkov telescope, known as MAGIC. He wanted to know whether someone was running a test on their project.

    “No, we are not doing a test,” Moretti said. “Why?”

    Within minutes, she was running down the road to investigate.

    Moretti’s specialty is gamma-ray bursts, incredibly powerful blasts of high-energy radiation marking stellar death. She was in the Canary Islands overseeing construction work on MAGIC’s successor, the Čerenkov Telescope Array.

    Čerenkov Telescope Array, http://www.isdc.unige.ch/cta/ at Cerro Paranal, located in the Atacama Desert of northern Chile searches for cosmic rays on Cerro Paranal at 2,635 m (8,645 ft) altitude, 120 km (70 mi) south of Antofagasta; and at at the Instituto de Astrofisica de Canarias (IAC), Roque de los Muchachos Observatory in La Palma, Spain

    While scientists have detected GRBs for decades, there seemed to be a limit on the energy level of the gamma rays they captured. Was the limit a feature of GRBs? Some scientists thought that it was not, and they hoped observations could prove it.

    If the very-high-energy gamma rays showed up the way some theorists suspected they would, the energy spectrum that observatories measured would show a second higher-energy intensity bump in the data.

    Some scientists had given up on the idea of the second bump—after decades’ worth of searching, it had yet to appear.

    But that night, January 14, 2019, with its very first detection of a GRB, MAGIC became the observatory that found the second bump—and helped change the scientific world’s understanding of one the great mysteries of the universe.

    “It was incredible,” says Moretti, an astrophysicist at the Institute for High Energy Physics in Barcelona, Spain. “The way you look for something for a long time, and then suddenly it materializes and it’s so bright, so undoubtful.”

    Bursts born of stellar death

    Gamma-ray bursts were serendipitously discovered in the midst of the Cold War, when the US military was scouring the sky for evidence of nuclear weapons. At the time, US satellites spied radiation with energy much higher than visible light that would have come from nuclear blasts. It wasn’t until the next decade, after those detections were declassified, that scientists realized the blasts were coming from cosmic sources. It was later still, in the 1990s, when they realized the signals were coming from outside the galaxy.

    Since then, several space-based observatories—including NASA’s Neil Gehrels Swift Observatory and the Gamma-ray bursts were serendipitously discovered in the midst of the Cold War, when the US military was scouring the sky for evidence of nuclear weapons. At the time, US satellites spied radiation with energy much higher than visible light that would have come from nuclear blasts. It wasn’t until the next decade, after those detections were declassified, that scientists realized the blasts were coming from cosmic sources. It was later still, in the 1990s, when they realized the signals were coming from outside the galaxy.

    Since then, several space-based observatories—including NASA’s Neil Gehrels Swift Observatory and the Fermi Gamma-ray Space Telescope, which is supported by NASA, the US Department of Energy and international partners—have been especially revolutionary to astronomers’ understanding of what leads to such enormously energetic blasts of gamma-ray radiation. Gamma-ray Space Telescope, which is supported by NASA, the US Department of Energy and international partners—have been especially revolutionary to astronomers’ understanding of what leads to such enormously energetic blasts of gamma-ray radiation.

    NASA Neil Gehrels Swift Observatory

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    GRBs come in two types: short- and long-duration, based on whether their initial gamma-ray blasts last less or more than two seconds. A short-duration GRB happens when two compact objects, such as two neutron stars, slam into each other. A long-duration GRB, on the other hand, results from a specific type of core-collapse supernova, what happens when a star around at least 10 times as massive as our sun exhausts the fuel supplies at its core, causing it to collapse into a black hole.

    In both GRB types, the energetic event (whether a collision or collapse) blasts out jets of particles traveling at nearly the speed of light. Interactions inside the jets—between blobs of plasma that are emitted at different times and have different speeds—create a GRB’s initial burst of gamma rays.

    As the jets travel through gases surrounding the event site, they create another characteristic feature of GRBs: the afterglow, which shines across the electromagnetic spectrum in radio up to gamma rays.

    A gamma-ray puzzle

    Astrophysicists have learned a great deal about how such cosmic events generate gamma rays and other electromagnetic radiation. According to astrophysicist David Williams, who has studied GRBs for decades, they produce what’s called synchrotron radiation. “As the burst ejecta plow into the surrounding medium, that burst accelerates electrons,” which spiral around magnetic field lines, shooting out photons like mud off a tractor tire.

    But some theorists have thought there could be more to the story—later in the afterglow, a second bump. The second bump would come from the electrons slamming into some of their just-produced photons and bumping those photons’ energies even higher in a process called synchrotron self-Compton.

    Twenty years ago, several theorists published papers arguing that, given what scientists knew then about GRBs, synchrotron self-Compton should occur. University of Nevada physicist Bing Zhang, who wrote one of those papers, says he was therefore not surprised by the MAGIC detection. “Synchrotron self-Compton is inevitable, and it should be detected,” he says.

    Searching for a second bump

    The space-based observatories that have provided so much information about GRBs have never seen the kind of gamma rays that would produce a second bump—because they can’t.

    This is for two reasons. First, Swift, which predominantly detects X-rays and ultraviolet rays, would need different technology to detect such high-energy rays. Second, space-based observatories tend to be equal to or smaller than the size of a full-sized refrigerator. Very-high-energy gamma rays are rare, and it takes a much larger detector than that to capture them.

    But satellites like Fermi and Swift can still help. When they detect a GRB, they automatically signal additional telescopes to swing around to take a closer look at what they’ve seen.

    That day in January 2019, the MAGIC telescope’s computer received the alert and reacted quickly. It analyzed where in the sky the GRB was and whether MAGIC could see it. When it determined it could, it gave a command to quickly move both of MAGIC’s 17-meter-wide telescopes’ thin mirrors, each mounted on a lightweight carbon-fiber frame.

    “In this whole process, there is no human,” Moretti says. “We received the alert more or less 20 seconds after the beginning of the GRB. Another 30 seconds—so 50 seconds from the GRB—and we were pointing.”

    It was around then that Nigro called. While on the phone, he emailed Moretti the first plot of the GRB signal, which sent Moretti running. “In five minutes, I was on site,” she says.

    On the computer screens in the control room, she watched the automatically generated analysis of how the signal’s energy changed over time. Moretti, Nigro and the other observers checked the location for other bright sources, noisy signals that could be confused with a GRB, and found none.

    It was MAGIC’s first detection of a GRB. And the source they saw was briefly 100 times as bright as gamma-ray astronomy’s calibration source, the Crab Nebula.

    Supernova remnant Crab nebula

    MAGIC collected photons over the next few hours with energies from 300 GeV up to 2 TeV, or 2 trillion times the energy of visible light. Once data across multiple wavelengths of radiation from other observatories were combined, the signal became clear: The spectrum in gamma-ray energies peaked not once, but twice.

    In that moment, Moretti says she knew “we were looking into the other component, the one that we had been searching for for a long time… I did not know that it was this beautiful, but I knew that it would come. It was just a matter of time.”

    More to come

    Moretti says she looks forward to the Čerenkov Telescope Array, the next-generation gamma-ray observatory she is also working on in the Canary Islands. Most of the more than 30 institutions that participate in MAGIC—in Germany, Spain, Italy, Japan, Switzerland, Croatia, Finland, Poland, India, Bulgaria, Brazil and Armenia—also participate in the CTA.

    Currently in the prototype stage and slated to begin observations in the mid 2020s, CTA will have several times the observing sensitivity as any of the current observatories. It will also be able to monitor a larger area of the sky. CTA will comprise two separate arrays, one in Chile and the other just down the street from MAGIC.

    The two-bump January 2019 GRB, along with a one-bump—but also promising—2018 GRB observation by the High Energy Stereoscopic System, or HESS, in Namibia, gives CTA researchers reason to expect many more GRB detections. The current estimates suggest CTA will capture a few each year.

    As more observations rack up, it will lead to an even better understanding of these enormously bright blasts.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 12:53 pm on August 13, 2020 Permalink | Reply
    Tags: , , , , Gamma rays detected using the prototype Schwarzschild-Couder Telescope (pSCT), , Supernova remnant Crab nebula, Very-high-energy gamma-ray astronomy, Čerenkov Telescope Array   

    From Čerenkov Telescope Array: “CTA Prototype Telescope, the Schwarzschild-Couder Telescope, Detects Crab Nebula” 

    From Čerenkov Telescope Array

    2020-June-01

    Project contacts:

    Center for Astrophysics | Harvard & Smithsonian
    Wystan Benbow
    617-496-7597
    wbenbow@cfa.harvard.edu

    University of Wisconsin
    Justin Vandenbroucke
    608-890-1477
    justin.vandenbroucke@wisc.edu

    University of California, Los Angeles
    Vladimir Vassiliev
    310-267-5878
    vvv@astro.ucla.edu

    Media contacts:

    Center for Astrophysics | Harvard & Smithsonian
    Fred Lawrence Whipple Observatory
    Amy Oliver
    801-783-9067
    amy.oliver@cfa.harvard.edu

    CTA Observatory
    Megan Grunewald
    +49 157 58795599
    mgrunewald@cta-observatory.org

    1
    Guests of the pSCT inauguration in January 2019 gather in front of the telescope. Credit: Deivid Ribeiro, Columbia University.

    On 1 June 2020, scientists from the Čerenkov Telescope Array (CTA) Consortium announced at the 236th meeting of the American Astronomical Society (AAS) that they have detected gamma rays from the Crab Nebula using a prototype telescope proposed for CTA, the prototype Schwarzschild-Couder Telescope (pSCT), proving the viability of the novel telescope design for use in gamma-ray astrophysics.

    Supernova remnant Crab nebula

    “The Crab Nebula is the brightest steady source of TeV, or very-high-energy, gamma rays in the sky, so detecting it is an excellent way of proving the pSCT technology,” said Justin Vandenbroucke, Associate Professor, University of Wisconsin. “Very-high-energy gamma rays are the highest energy photons in the universe and can unveil the physics of extreme objects including black holes and possibly dark matter.”

    Detecting the Crab Nebula with the pSCT is more than just proof-positive for the telescope itself. It lays the groundwork for the future of gamma-ray astrophysics. “We’ve established this new technology, which will measure gamma rays with extraordinary precision, enabling future discoveries,” said Vandenbroucke. “Gamma-ray astronomy is already at the heart of the new multi-messenger astrophysics, and the SCT technology will make it an even more important player.”

    The use of secondary mirrors in gamma-ray telescopes is a leap forward in innovation for the relatively young field of very-high-energy gamma-ray astronomy, which has moved rapidly to the forefront of astrophysics. “Just over three decades ago, TeV gamma rays were first detected in the universe, from the Crab Nebula, on the same mountain where the pSCT sits today,” said Vandenbroucke. “That was a real breakthrough, opening a cosmic window with light that is a trillion times more energetic than we can see with our eyes. Today, we’re using two mirror surfaces instead of one, and state-of-the-art sensors and electronics to study these gamma rays with exquisite resolution.”

    See the full article here.

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    Please help promote STEM in your local schools.

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    About CTA

    The Čerenkov Telescope Array (CTA) is a global initiative to build the world’s largest and most sensitive high-energy gamma-ray observatory with tens of telescopes planned on two sites: one in the northern hemisphere on the island of La Palma, Spain, and the other in the southern hemisphere near Paranal, Chile. CTA will be the foremost global observatory for very high-energy gamma-ray astronomy over the next decade and beyond and will be the first ground-based gamma-ray astronomy observatory open to the world-wide astronomical and particle physics communities. CTA will address some of the greatest mysteries in astrophysics, detecting gamma rays with an unprecedented sensitivity and expanding the cosmic source catalogue tenfold. CTA is a unique, ambitious large-scale infrastructure that will expand observations up to a region of the spectrum that has never been seen, opening an entirely new window to our Universe. The CTAO gGmbH serves to prepare the design and implementation of the CTA Observatory. The CTAO works in close cooperation with the CTA Consortium composed of 1500+ members from 31 countries, which is responsible for directing the science goals of the Observatory and is involved in the design and supply of instrumentation. The CTAO is governed by a council of shareholders from 11 countries and one intergovernmental organization, as well as associate members from two countries.

     
  • richardmitnick 12:30 pm on August 13, 2020 Permalink | Reply
    Tags: "Prototype LST-1 Detects Very-High Energy Emission from the Crab Pulsar", , , , , Gamma-ray events, Čerenkov Telescope Array   

    From Čerenkov Telescope Array: “Prototype LST-1 Detects Very-High Energy Emission from the Crab Pulsar” 

    From Čerenkov Telescope Array

    1
    Credit: Tomohiro Inada

    Between January and February 2020, the prototype Large-Sized Telescope (LST), the LST-1, observed the Crab Pulsar, the neutron star at the centre of the Crab Nebula, during engineering runs to verify the telescope performance and adjust operating parameters.

    Supernova remnant Crab nebula

    Pulsars, which are rapidly rotating and strongly magnetized neutron stars that emit light in the form of two beams, are much more challenging to detect due to their weak signals and the typical dominance of the foreground gamma-ray signal from the surrounding nebulae. Despite hundreds of observation hours by IACTs around the globe, only four pulsars emitting signals in the very high-energy gamma-ray regime have been discovered, so far. Now that the LST-1 has shown that it can detect the Crab pulsar, it joins the field of telescopes capable of detecting gamma-ray pulsars.

    “This milestone shows us that the LST-1 is already performing at an extraordinary level, detecting a challenging source in record time,” says Masahiro Teshima, Director of Max-Planck-Institute for physics in Munich and Principal Investigator of LST. “Pulsars are one of the key scientific targets of the LSTs, and it’s exciting to imagine what we’ll be able to achieve when the telescope is fully commissioned and operational.”

    2
    Phasogram of Crab Pulsar as measured by the LST-1. The pulsar is known to emit pulses of gamma rays during phases P1 and P2. The shown significance is calculated considering source emission from those phases (in red) and background events from phases in grey. Credit: LST Collaboration.

    The data set collected includes 11.4 hours from eight observation nights. The above figure shows the resulting phasogram, plotting the gamma-ray events as a function of the pulsar rotation phase. In the phase regions marked as P1 and P2, more gamma rays are expected as the Crab pulsar emits towards the Earth. The emission detected in all phases (marked green) is a mixture of different background contributions, including the irreducible steady emission from the Crab Nebula. The signal detected with the LST-1 (marked red) is undeniably significant for phase P2, while the signal during P1 is still marginal.

    See the full article here.

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    About CTA

    The Čerenkov Telescope Array (CTA) is a global initiative to build the world’s largest and most sensitive high-energy gamma-ray observatory with tens of telescopes planned on two sites: one in the northern hemisphere on the island of La Palma, Spain, and the other in the southern hemisphere near Paranal, Chile. CTA will be the foremost global observatory for very high-energy gamma-ray astronomy over the next decade and beyond and will be the first ground-based gamma-ray astronomy observatory open to the world-wide astronomical and particle physics communities. CTA will address some of the greatest mysteries in astrophysics, detecting gamma rays with an unprecedented sensitivity and expanding the cosmic source catalogue tenfold. CTA is a unique, ambitious large-scale infrastructure that will expand observations up to a region of the spectrum that has never been seen, opening an entirely new window to our Universe. The CTAO gGmbH serves to prepare the design and implementation of the CTA Observatory. The CTAO works in close cooperation with the CTA Consortium composed of 1500+ members from 31 countries, which is responsible for directing the science goals of the Observatory and is involved in the design and supply of instrumentation. The CTAO is governed by a council of shareholders from 11 countries and one intergovernmental organization, as well as associate members from two countries.

     
  • richardmitnick 7:31 am on January 30, 2020 Permalink | Reply
    Tags: (MOU)-Memorandum of Understanding, , , , , CTA will comprise two arrays on different continents observing gamma rays: one in Chile at ESO’s Cerro Paranal and one in Spain on La Palma in the Canary Islands., , , , SKA will have radio telescopes in Australia and South Africa., Čerenkov Telescope Array   

    From SKA: “SKA signs cooperation agreement with Čerenkov Telescope Array” 

    SKA South Africa


    From SKA

    29 January 2020

    The SKA Organisation (SKAO) [all telescope images below] will engage in closer collaboration with the Čerenkov Telescope Array Observatory (CTAO) under a new agreement signed by the two research infrastructures.

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    The Memorandum of Understanding (MOU) will facilitate greater sharing of knowledge and expertise in areas including engineering, science, technology and administration.

    SKAO and CTAO are both large international collaborations and have several member countries in common, including many European countries but also astronomy organisations in Australia and South Africa. Like the SKA, which will have radio telescopes in Australia and South Africa, CTA will also comprise two arrays on different continents observing gamma rays: one in Chile at ESO’s Cerro Paranal and one in Spain on La Palma in the Canary Islands.

    The two observatories are due to begin delivering science within just a few years of each other.

    Both have also begun transitions on the governance front; the SKA is becoming an intergovernmental organisation or IGO, while CTAO is becoming a European Research Infrastructure Consortium (ERIC).

    “Both the SKA and CTA are pushing the boundaries of what’s possible technically, scientifically and logistically, and some of the challenges that brings are common to both projects,” says Simon Berry, Director of Strategy for the SKA. “This MOU formalises our relationship, so we can keep learning from each other’s experiences and share expertise for the benefit of both observatories.”

    “In this age of multi-messenger astronomy, building alliances with observatories across the spectrum are critical to achieving our common missions to expand our view and understanding of the Universe,” says Federico Ferrini, CTAO Managing Director. “The CTAO-SKAO partnership was an obvious fit due to our vast similarities, and we are looking forward to the collaboration.”

    While the respective telescopes will observe opposite ends of the spectrum, there are exciting areas of scientific synergy between them. Both radio and gamma rays are a probe of the violent and variable universe, including the study of active galactic nuclei, transient events such as gamma-ray bursts and fast radio bursts, accretion into compact objects and gravitational wave counterparts.

    As the flagship very high-energy gamma-ray observatory for the coming decades, CTA is one of several next-generation facilities targeting other wavelengths or cosmic messengers (detections that do not use photons, such as neutrinos or gravitational waves) which will be complementary to the SKA. Coordinated observations between such facilities can give a more complete picture of astronomical sources and phenomena, resulting in greatly enhanced scientific discoveries.

    See the full article here .

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    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA

    Murchison Widefield Array,SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)

    SKA Hera at SKA South Africa

    SKA Pathfinder – LOFAR location at Potsdam via Google Images

    About SKA

    The Square Kilometre Arraywill be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

    The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.

    Already supported by 10 member countries – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom – SKA Organisation has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. Construction of the SKA is set to start in 2018, with early science observations in 2020.

     
  • richardmitnick 5:29 pm on September 14, 2019 Permalink | Reply
    Tags: , , , , , , Čerenkov Telescope Array   

    From Symmetry: “A new way to study high-energy gamma rays” 

    From Symmetry

    09/03/19
    Jim Daley

    The Čerenkov Telescope Array will combine experimental and observatory-style approaches to investigate the universe’s highest energies.

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    They permeate the cosmos, whizzing through galaxies and solar systems at energies far higher than what even our most powerful particle accelerators can achieve. Emitted by sources such as far-distant quasars, or, closer to Earth, occasionally ejected from the remnants of supernovae, high-energy cosmic rays are believed to play a role in the evolution of galaxies and the growth of black holes.

    Exactly how cosmic rays originate remains a mystery. Now, an ambitious project—part observatory, part experiment—is preparing to investigate them by studying the gamma rays they produce at sensitivities never achieved before.

    The Čerenkov Telescope Array being built in Chile and Spain’s Canary Islands is the newest generation of ground-based gamma-ray detectors. CTA involves collaborators from 31 countries and comprises more than 100 telescopes of varying sizes. Its detectors will be 10 times more sensitive to gamma rays than existing instruments, which will allow scientists to investigate their properties at a breathtaking range of energy levels—from about 20 billion electronvolts up to 300 trillion electronvolts. This is far above current capabilities: Existing gamma-ray observatories’ energy ranges top out at about 50 trillion electronvolts.

    Rene Ong, an astrophysicist at UCLA and the co-spokesperson for the project, says that CTA is unique in that it will function as both an experiment—zeroing in to investigate specific points and topics of interest—and an observatory—creating an overall record of a portion of the night sky over time.

    It will be the first ground-based gamma-ray observatory, and users will be granted observatory access time for their own projects in a proposal-driven program. “CTA will operate like an astronomical facility with a mix of guest-observer time, dedicated time for major observation projects, and time reserved for the CTA observatory director,” he says.

    Part of what makes CTA an astronomical observatory is that it will make its data freely available, explains Ulisses Barres, an astrophysicist at the Brazilian Center for Physical Research who is leading part of that country’s contribution to CTA’s design and construction.

    Until now, very-high-energy gamma-ray band astronomy research has been conducted by “closed” research groups, which have reserved most or all of their data for their own use. CTA will not only make its data public; just like a typical observatory, it will also structure its data to make it accessible even to nonspecialists and people in other scientific fields.

    “That’s because CTA wants to kind of kick-start astronomy in the [high-energy gamma-ray] band in a new way,” Barres says. “People from other fields can request data from CTA in a competitive way and analyze it, pretty much like what an experimental telescope does.”

    Elisabete de Gouveia Dal Pino, an astrophysicist at the University of São Paulo and also one of the leaders of the CTA Consortium in Brazil, says the project’s design will allow scientists to investigate some of the most energetic events that occur anywhere in the universe. These events are theorized to come mostly from compact sources like supermassive black holes and supernovae explosions.

    “There is a whole slew of processes and particles that we can decipher [by] observing the universe in gamma rays,” Dal Pino says. Other wavelengths have already been probed and are well-developed fields of study, she explains. “This is the last energy band window that we are currently able to open on the universe right now.”

    CTA may also test physics beyond the Standard Model, Ong says. In particular, it will search for dark matter, which scientists think makes up 85% of the known matter in the universe but has yet to be detected, let alone fully understood. It’s possible that gamma rays are produced when dark matter particles bump into one another and self-annihilate.

    CTA’s dark matter program will attempt to discover the nature of this phenomenon by observing the galactic halo, a roughly spherical, thinly populated area that surrounds the visible galaxy and is believed to be home to these particles.

    For now, the project is still in its design and construction phase. Barres says he expects a “critical mass” of telescopes—enough to begin taking useable data—in the northern hemisphere by 2022. “We expect that by the middle of the next decade, CTA may already be fully operational,” he says. “For now, there is a lot of coordination to be done among the partner institutions.”

    See the full article here .


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    Please help promote STEM in your local schools.


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:22 am on October 2, 2017 Permalink | Reply
    Tags: , , , , , , Čerenkov Telescope Array   

    From astrobites: “The Science of the Next Generation” 

    Astrobites bloc

    Astrobites

    Oct 2, 2017
    Kelly Malone

    Title: Science with the Cherenkov Telescope Array
    Authors: The Cherenkov Telescope Array Consortium
    1
    Status: To be published in the International Journal of Modern Physics D, [open access]

    Today’s document shows the far-reaching goals of the next-generation gamma-ray experiment, the Cherenkov Telescope Array (CTA).

    Cherenkov Telescope Array, http://www.isdc.unige.ch/cta/ at Cerro Paranal, located in the Atacama Desert of northern Chile on Cerro Paranal at 2,635 m (8,645 ft) altitude, 120 km (70 mi) south of Antofagasta; and at at the Instituto de Astrofisica de Canarias (IAC), Roque de los Muchachos Observatory in La Palma, Spain

    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain

    HESS Cherenko Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg

    Gamma rays are important probes of cosmic rays, charged particles of which the origins and acceleration mechanisms are still unknown. Over the course of a hefty 211 pages and representing years of work, the authors explain the science goals of this experiment, which will greatly enhance our knowledge of the universe when it comes online in a few years.

    Gamma rays are the radiation at the far end of the electromagnetic spectrum. Gamma rays are created in the same astrophysical processes that create cosmic rays, but since they are electrically neutral, they do not bend in magnetic field lines on their journey to Earth and therefore point back to their sources. Astrophysical TeV gamma rays, which CTA will probe, were first detected in the late 1980s. Many experiments have been built in this energy range since then, but CTA will offer improvements in sensitivity and energy range over all of the current and past experiments.

    CTA will consist of two arrays of differently-sized telescopes (one in the Northern Hemisphere and one in the Southern Hemisphere) that will detect the Cherenkov radiation that is produced when a gamma ray interacts with molecules in our atmosphere. The Southern site, in Chile, will have 99 large, medium, and small-sized telescopes, while the Northern site, in Spain, will only have 19 medium and small ones. (This discrepancy is because the inner regions of our Galaxy, one of the key science targets, is only visible in the Southern hemisphere). These telescopes will look quite different from the conventional optical telescopes you may be used to. Veritas, one of the current generation experiments, has an explanation of their telescope design here.

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    Figure 1: The differential sensitivity of CTA, as compared to current gamma-ray experiments. The curves show the particle flux needed for a five sigma detection as a function of energy. A line further down the plot means that the experiment is sensitive to dimmer sources. (Source: Figure 1.1 from the document)

    As CTA will contain more telescopes than current telescope array, it is an immediate improvement. For example, the sensitivity will increase by an order of magnitude at 1 TeV, the angular resolution will improve (leading to the ability to image the tiny sources as well as details in larger ones) and the energy range will be from 20 GeV-300 TeV (HAWC, another gamma-ray experiment, currently has the highest energy range but maxes out around 100 TeV).

    HAWC High Altitude Cherenkov Gamma Ray Collaboration, Sierra Negra volcano near Puebla, Mexico

    Unlike other gamma-ray experiments, CTA will be an open observatory. This means that any scientist will be able to submit Guest Observer proposals to study sources of interest. Additionally, all data will become publicly available one year after it is collected. Approximately 40% of the observing time will be reserved for a Core Program of Key Science Projects, decided of a series of workshops over the years.

    The Key Science projects are far reaching and cover many areas of astrophysics: in-depth observations of the Galactic Centre and a survey of the Galactic Plane, studies of the Large Magellanic Cloud, robust programs for extragalactic sources and transients, searches for cosmic ray PeVatrons, and study galaxy clusters, and star forming systems are just some of the science that will be covered. Additionally, there will be a dark matter program and some opportunity to study other, non-gamma ray science.

    3
    Figure 2: A zoomed in portion a simulated galactic plane, showing what CTA might expect to observe. The plot covers 20 degrees in Galactic longitude (Source: Figure 1.2 from the paper)

    The questions that these science programs will answer will cover three broad themes that probe some of the biggest unknowns in our universe. Theme #1 is “Understanding the Origin and Role of Relativistic Cosmic Particles“. This is where the Collaboration will attempt to answer questions such as the sites and mechanisms of cosmic particle acceleration and the role these particles play in star formation and galaxy evolution. Theme #2, “Probing Extreme Environments“, will deal with the physical processes that occur close to neutron stars and black holes, including their jets, winds, and the explosions that are prone to happening in these environments. Theme #3, “Exploring Frontiers in Physics” deals with fundamental questions about the nature of dark matter, including whether axion-like particles exist and where quantum gravity affects how photons propagate through space.

    CTA will not be online for quite a few years- although the collaboration and idea has existed in some form for the better part of a decade, the sites were only chosen that year and much of the work in the last few years has been related to the telescope design. The project is currently in a “pre-construction” phase, with construction beginning next year, the first observations happening in 2021, and the construction finishing in 2024. When it does come online, though, it will greatly enhance our knowledge of gamma-ray astrophysics.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 2:08 pm on December 2, 2016 Permalink | Reply
    Tags: , , , , Čerenkov Telescope Array   

    From Symmetry: “Viewing our turbulent universe” 

    Symmetry Mag
    Symmetry

    12/02/16
    Liz Kruesi

    Construction has begun for the Cherenkov Telescope Array [CTA], a discovery machine that will study the highest energy objects and events across the entire sky.

    1
    Daniel Mazinkn, CTA Observatory

    Billions of light-years away, a supermassive black hole is spewing high-energy radiation, launching it far outside of the confines of its galaxy. Some of the gamma rays released by that turbulent neighborhood travel unimpeded across the universe, untouched by the magnetic fields threading the cosmos, toward our small, rocky, blue planet.

    We have space-based devices, such as the Fermi Gamma-ray Space Telescope, that can detect those messengers, allowing us to see into the black hole’s extreme environment or search for evidence of dark matter.

    NASA/Fermi Telescope
    NASA/Fermi Telescope

    But Earth’s atmosphere blocks gamma rays. When they meet the atmosphere, sequences of interactions with gas molecules break them into a shower of fast-moving secondary particles. Some of those generated particles—which could be, for example, fast-moving electrons and their antiparticles, positrons—speed through the atmosphere so quickly that they generate a faint flash of blue light, called Cherenkov radiation.

    A special type of telescope—large mirrors fitted with small reflective cones to funnel the faint light—can detect this blue flash in the atmosphere. Three observatories equipped with Cherenkov telescopes look at the sky during moonless hours of the night: VERITAS in Arizona has an array of four; MAGIC in La Palma, Spain, has two; and HESS in Namibia, Africa, has an array of five.

    CfA/VERITAS, AZ, USA
    CfA/VERITAS, AZ, USA

    MAGIC Cherenkov gamma ray telescope  on the Canary island of La Palma, Spain
    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain

    HESS Cherenko Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg
    HESS Cherenko Array, located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg

    All three observatories have operated for at least 10 years, revealing a gamma-ray sky to astrophysicists.

    “Those telescopes really have helped to open the window, if you like, on this particular region of the electromagnetic spectrum,” says Paula Chadwick, a gamma-ray astronomer at Durham University in the United Kingdom. But that new window has also hinted at how much more there is to learn.

    “It became pretty clear that what we needed was a much bigger instrument to give us much better sensitivity,” she says. And so gamma-ray scientists have been working since 2005 to develop the next-generation Cherenkov observatory: “a discovery machine,” as Stefan Funk of Germany’s Erlangen Centre for Astroparticle Physics calls it, that will reveal the highest energy objects and events across the entire sky. This is the Cherenkov Telescope Array (CTA), and construction has begun.

    Ironing out the details

    As of now, nearly 1400 researchers and engineers from 32 countries are members of the CTA collaboration, and membership continues to grow. “If we look at the number of CTA members as a function of time, it’s essentially a linear increase,” says CTA spokesperson Werner Hofmann.

    Technology is being developed in laboratories spread across the globe: in Germany, Italy, the United Kingdom, Japan, the United States (supported by the NSF—given the primarily astrophysics science mission of the CTA, it is not a part of the Department of Energy High Energy Physics program), and others. Those nearly 1400 researchers are collaborating and working together to gain a better understanding of how our universe works. “It’s the science that’s got everybody together, got everybody excited, and devoting so much of their time and energy to this,” Chadwick says.

    3
    G. Pérez, IAC, SMM

    The CTA will be split between two locations, with one array in the Northern Hemisphere and a larger one in the Southern Hemisphere. The dual location enables a view of the entire sky.

    CTA’s northern site will host four large telescopes (23 meters wide) and 15 medium telescopes (12 meters wide). The southern site will also host four large telescopes, plus 25 medium and 70 small telescopes (4 meters) that will use three different designs. The small telescopes are equipped to capture the highest energy gamma rays, which emanate, for example, from the center of our galaxy. That high-energy source is visible only from the Southern Hemisphere.

    In July 2015, the CTA Observatory (CTAO) council—the official governing body that acts on behalf of the observatory—chose their top locations in each hemisphere. And in 2016, the council has worked to make those preferences official. On September 19 the council and the Instituto de Astrofísica de Canarias signed an agreement stating that the Roque de los Muchachos Observatory on the Canary Island of La Palma would host the northern array and its 19 constituent telescopes. This same site hosts the current-generation Cherenkov array MAGIC.

    IAC

    Construction of the foundation is progressing at the La Palma site to prepare for a prototype of the large telescope. The telescope itself is expected to be complete in late 2017.

    “It’s an incredibly aggressive schedule,” Hofmann says. “With a bit of luck we’ll have the first of these big telescopes operational at La Palma a year from now.”

    While the large telescope prototype is being built on the La Palma site, the medium and small prototype telescopes are being built in laboratories across the globe and installed at observatories similarly scattered. The prototypes’ optical designs and camera technologies need to be tested in a variety of environments. For example, the team working on one of the small telescope designs has a prototype on the slope of Mount Etna in Sicily. There, volcanic ash sometimes batters the mirrors and attached camera, providing a test to ensure CTA telescopes and instruments can withstand the environment. Unlike optical telescopes, which sit in protective domes, Cherenkov telescopes are exposed to the open air.

    The CTAO council expects to complete negotiations with the European Southern Observatory before the end of 2016 to finalize plans for the southern array. The current plan is to build 99 telescopes in Chile.

    ESO Bloc Icon

    This year, the council also chose the location of the CTA Science Management Center, which will be the central point of data processing, software updates and science coordination. This building, which will be located at Deutsches Elektronen-Synchrotron (also known as DESY) outside of Berlin, has not yet been built, but Hofmann says that should happen in 2018.

    DESY

    The observatory is on track for the first trial observations (essentially, testing) in 2021 and the first regular observations beginning in 2022. How close the project’s construction stays to this outlined schedule depends on funding from nations across the globe. But if the finances remain on track, then in 2024, the full observatory should be complete, and its 118 telescopes will then look for bright flashes of Cherenkov light signaling a violent event or object in the universe.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:27 pm on December 11, 2015 Permalink | Reply
    Tags: , , , Čerenkov Telescope Array   

    From Symmetry: “The next gamma-ray eye on the sky” 

    Symmetry

    12/11/15
    Liz Kruesi

    Scientists have successfully tested the first prototype camera for the Cherenkov Telescope Array.

    1
    DESY/Milde Science Comm./Exozet

    Telescope arrays VERITAS, HESS and MAGIC have spied active supermassive black holes, the remnants of the explosions of massive stars, binary star systems, and galaxies actively churning out new stars.

    Veritas Telescope
    VERITAS

    HESS Cherenko Array
    HESS Cherenko Array

    MAGIC Telescope
    MAGIC

    This is possible thanks to what all of these cosmic objects have in common: They are all sources of high-energy gamma rays. VERITAS, HESS and MAGIC all look for the optical light produced when those gamma rays interact with Earth’s atmosphere.

    One gamma-ray source that continues to elude these powerful telescopes is the brightest electromagnetic event known to occur in the universe: a gamma-ray burst. But a new telescope array currently under development might be able to catch one.

    The Cherenkov Telescope Array, or CTA, will cover a substantially larger area on the ground, making it an enormous “bucket” to collect incoming gamma-ray-produced radiation.

    Cherenkov Telescope Array
    CTA

    It will also be able to collect data during almost twice as many hours per year as current arrays.

    The array will study the entire range of gamma-ray sources. It also has the capability to detect the annihilation signature of dark matter particles.

    “We’re really hoping to find something new, some new type of high-energy astrophysical phenomenon,” says Rene Ong, the CTA consortium co-spokesperson.

    Scientists successfully operated the first CTA prototype camera in late November. The full array is scheduled to start running in the 2020s.

    The usefulness of gamma rays

    Gamma rays are almost ideal messengers of high-energy particle astrophysics. They are created in the most energetic processes in the universe. And, like all other forms of light, they are electrically neutral and thus aren’t buffeted by galactic magnetic fields as they travel through space. This means scientists can use them to point back to their sources.

    The drawback is that these messengers can’t make it through Earth’s atmosphere. Instead, they interact and produce a shower of lower-energy particles.

    If some of those are traveling at a velocity faster than the speed of light in the gaseous medium of the atmosphere, they will create flashes of light peaking between blue and ultraviolet, akin to a sonic boom following a supersonic jet. This light is called Cherenkov radiation, and it’s what ground-based high-energy gamma-ray telescopes actually detect.

    VERITAS in Arizona, HESS in Namibia, and MAGIC on the Canary island of La Palma are arrays of optical telescopes that have been detecting this light for about a decade. VERITAS contains four of these scopes, HESS has five, and MAGIC has two. The weak light reflects off each segmented primary mirror and is funneled to a “camera.” Each telescope’s camera is made of hundreds to thousands of photomultiplier tubes which convert the incoming photons into electrical signals.

    With the next-generation CTA, scientists hope to catch a gamma-ray burst with a ground-based telescope array for the first time. They want to know the underlying physics of these blasts, the sources of which are thought to be located millions to billions of light-years away.

    Scientists have seen gamma-ray bursts with space-based instruments, such as the Fermi Gamma-Ray Space Telescope and Swift.

    NASA Fermi Telescope
    NASA/Fermi

    NASA SWIFT Telescope
    NASA/Swift

    But only a ground-based array could detect their highest-energy gamma rays, those above 100 billion electronvolts. And a large ground-based array such as the CTA, which will cover 10 square kilometers in the south and 1 square kilometer in the north, would be able to capture much more information.
    Building the CTA

    An international consortium of nearly 1300 researchers from 31 countries is working toward building the CTA. The array will focus on a wider gamma ray energy range than the currently operating instruments—seeing between 20 billion electronvolts and 300 trillion electronvolts—and will do so with 10 times the sensitivity.

    The CTA will consist of two detection sites on Earth, one in each hemisphere. At Cerro Paranal in Chile’s Atacama Desert, approximately 100 telescopes spread across an area of about 10 square kilometers will scan the Southern sky. On the Spanish island of La Palma, some 19 telescopes will watch the Northern sky. The CTA Observatory is in the final negotiations with representatives from both locations to finalize the agreements to host the arrays.

    Both the northern and southern arrays will each have four large telescopes, each 23 meters wide and spaced about 100 meters apart from one another, clustered toward the center of the array. Moving outward will be telescopes in the 10 to 12 meters range. The northern array will have 15 of these medium-sized telescopes, while the southern array will have 25. The Cerro Paranal location additionally will host approximately 70 4-meter-wide telescopes, farther out from the array’s center.

    The 70 small telescopes will use new detectors made of silicon. These have several advantages over the current design, says University of Oxford graduate student Andrea De Franco, “but the most sexy for us is they can resist bright night-sky background.”

    That means they can detect Cherenkov light even in bright moonlight, something VERITAS, HESS and MAGIC cannot do. This new technology will let the CTA observatory operate for about 16 to 17 percent of the hours in a year; current arrays can observe during only about 10 percent.

    Work in progress

    CTA is in the development phase right now, meaning the consortium members are developing and testing the hardware, verifying how to deploy and operate the instruments, and simulating the best layout of those telescopes at each site.

    In October, the CTA project began constructing the large telescope prototype at La Palma.

    Two medium-sized telescope prototypes are also under construction: A two-mirror design with a 10-meter primary mirror is being built in southern Arizona; a prototype of a single-mirror, 12-meter-wide design is in testing in Berlin, and its camera is nearly complete.

    All three small-sized prototypes are well underway. A single-mirror, 4-meter design has been constructed in Krakow, Poland; a two-mirror, 4-meter design is operational near Mount Etna, Italy; and another two-mirror, 4-meter design was just inaugurated December 1 outside of Paris.

    De Franco has spent the last two years building and testing the camera for the Paris-based prototype in addition to helping commission it before the inauguration. On November 26, he and his colleagues proved the design was working—even with the City of Light nearby. The camera recorded Cherenkov light, making it the first CTA prototype fully working and observing.

    De Franco says it’s more likely that the light was part of a particle shower caused by an incoming cosmic ray rather than a gamma ray. But even if it was, this detection marked yet another step forward along the path to build science’s next gamma-ray eye scouring the sky.

    The next step will be to construct and deploy the pre-production telescopes at the actual array sites.

    “Ideally, [each of these] is identical to the final production telescope,” says CTA Project Manager Christopher Townsley. “It’s just that we will always learn something from putting it in the desert.”

    Members of the CTA project expect to begin this phase in spring 2017, depending on the availability of funding.

    Once the pre-production telescopes are operational, data collection can begin, though it won’t be anywhere near the quality expected from the full observatory. According to the current timeline, most of the telescopes at both arrays will be complete in 2020 or 2021.

    At that point, the data will surpass what today’s best gamma-ray instruments can obtain. And CTA will only get better from there.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:13 pm on July 16, 2015 Permalink | Reply
    Tags: , , , , Čerenkov Telescope Array   

    From ESO: “Paranal Observatory First Choice to Host World’s Largest Array of Gamma-ray Telescopes” 


    European Southern Observatory

    16 July 2015
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Temp 0

    On 15 and 16 July 2015, the Cherenkov Telescope Array (CTA) Resource Board decided to enter into detailed contract negotiations for hosting the CTA’s southern hemisphere array within the grounds of the Paranal Observatory, one of ESO’s sites in Chile. Similar negotiations for a northern site on La Palma are also starting.

    2
    CTA Array

    The CTA project is an initiative to build the next generation of ground-based instruments designed for the detection of very high energy gamma-rays. Gamma rays are emitted by the hottest and most powerful objects in the Universe — such as supermassive black holes, supernovae and possibly remnants of the Big Bang. The array will provide valuable deeper insights into the high-energy Universe.

    Although gamma rays don’t make it to the Earth’s surface, the CTA’s mirrors and high-speed cameras will capture short-lived flashes of the characteristic eerie blue Cherenkov radiation that is produced when the gamma rays interact with the Earth’s atmosphere. Pinpointing the source of this radiation will allow each gamma ray to be traced back to its cosmic source.

    The CTA Resource Board is composed of representatives of ministries and funding agencies from Austria, Brazil, the Czech Republic, France, Germany, Italy, Namibia, the Netherlands, Japan, Poland, South Africa, Spain, Switzerland and the and the United Kingdom. After months of negotiations and careful consideration of extensive studies of the environmental conditions, simulations of the science performance and assessments of construction and operation costs the Board has decided to start contract negotiations with ESO. The Namibian and Mexican sites will be kept as viable alternatives.

    In order for the CTA to maximise its coverage of the night sky, the array will consist of about 100 telescopes on the Chile site in the southern hemisphere and about 20 telescopes at the northern site.

    The Chile site for the CTA is less than ten kilometres southeast of the location of the Very Large Telescope, within the grounds of ESO’s Paranal Observatory in the Atacama Desert. This is considered one of the driest and most isolated regions on Earth — an astronomical paradise. In addition to the ideal conditions for year-round observation, installing the CTA at the Paranal Observatory offers the CTA the opportunity to take advantage of the existing infrastructure (roads, accommodation, water, electricity, etc.) and access to established facilities and processes for the construction and operation of the telescope array.

    Currently in its pre-construction phase, determination of the array sites is a critical factor in the CTA construction project.

    More Information

    The CTA aims to build the world’s largest and most sensitive high-energy gamma-ray telescope array. Over 1000 scientists and engineers from five continents, 31 countries (Argentina, Armenia, Australia, Austria, Brazil, Bulgaria, Canada, Chile, Croatia, the Czech Republic, Finland, France, Germany, Greece, India, Ireland, Italy, Japan, Mexico, Namibia, the Netherlands, Norway, Poland, Slovenia, South Africa, Spain, Sweden, Switzerland, the United Kingdom, the United States of America and Ukraine) and over 170 research institutes participate in the CTA project. The CTA will serve as an open facility to a wide astrophysics community and provide a deep insight into the non-thermal, high-energy Universe. The CTA will detect high-energy radiation with unprecedented accuracy and approximately ten times the sensitivity of current instruments, providing novel insights into some of the most extreme and violent events in the Universe.

    See the full article here.

    Please help promote STEM in your local schools.
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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    LaSilla

    ESO VLT Interferometer
    VLT

    ESO Vista Telescope
    VISTA

    ESO VLT Survey telescope
    VLT Survey Telescope

    ALMA Array
    ALMA

    ESO E-ELT
    E-ELT

    ESO APEX
    Atacama Pathfinder Experiment (APEX) Telescope

     
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