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  • richardmitnick 4:32 pm on September 11, 2017 Permalink | Reply
    Tags: Caltech/MIT Advanced aLigo, ,   

    From Universe Today: “Gravitational Waves will let us see Inside Stars as Supernovae Happen” 

    universe-today

    Universe Today

    11 Sept , 2017
    Matt Williams

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    Artistic representation of the material around the supernova 1987A. Credit: ESO/L. Calçada

    On February 11th, 2016, scientists at the Laser Interferometer Gravitational-wave Observatory (LIGO) announced the first detection of gravitational waves.


    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

    This development, which confirmed a prediction made by Einstein’s Theory of General Relativity a century ago, has opened up new avenues of research for cosmologists and astrophysicists. Since that time, more detections have been made, all of which were said to be the result of black holes merging.

    However, according to a team of astronomers from Glasgow and Arizona, astronomers need not limit themselves to detecting waves caused by massive gravitational mergers. According to a study they recently produced, the Advanced LIGO, GEO 600, and Virgo gravitational-wave detector network could also detect the gravitational waves created by supernova. In so doing, astronomers will able to see inside the hearts of collapsing stars for the first time.

    The study, titled Inferring the Core-Collapse Supernova Explosion Mechanism with Three-Dimensional Gravitational-Wave Simulations, recently appeared online. Led by Jade Powell, who recently finished her PhD at the Institute for Gravitational Research at the University of Glasgow, the team argue that current gravitational wave experiments should be able to detect the waves created by Core Collapse Supernovae (CSNe).

    See the full article here .

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  • richardmitnick 11:23 am on September 4, 2017 Permalink | Reply
    Tags: , Caltech/MIT Advanced aLigo, , Constructive interference: CERN and gravitational waves   

    From CERN: “Constructive interference: CERN and gravitational waves” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    4 Sep 2017
    Stefania Pandolfi

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    Gravitational waves as emitted during a black hole merger. (Image credit: S. Ossokine, A. Buonanno, Max Planck Institute for Gravitational Physics, Simulating eXtreme Spacetimes project, D. Steinhauser, Airborne Hydro Mapping GmbH)

    What do gravitational waves – ripples in the fabric of space-time caused by violent energetic processes in the universe – have to do with particle physics? At first sight, not much. But on 1 September scientists from the gravitational-wave community and CERN met to identify technology parallels.

    As CERN works towards a major upgrade of the Large Hadron Collider (LHC), the High Luminosity LHC, gravitational wave scientists are also contemplating major upgrades to current facilities. These will enrich the vista of the universe opened up in February 2016 when the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo collaborations announced the long-awaited first detection of gravitational waves, 100 years after their prediction by Einstein’s theory of gravity: general relativity.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Gravitational waves were detected using large “interferometers”. These L-shaped tubes with 4-km-long arms contain a series of mirrors and lasers that are sensitive to any slight distortion in the apparatus caused by a passing gravitational wave.


    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

    Now the gravitational-wave community is exploring several technologies to improve the sensitivity of the current observatories.

    “Technological R&D and design efforts for third-generation gravitational detectors may have interesting overlaps both with CERN capabilities and possible future directions,” says Barry Barish of the California Institute of Technology, one of the founders of the LIGO experiment.

    Next-generation interferometers could have much longer arms, be located underground to reduce seismic noise, or be cooled to cryogenic temperatures to reduce thermal interference. Expertise in vacuum, cryogenics and control systems is therefore of particular relevance, as well as how to deal with large volumes of data. CERN can also offer insights into how to organise the large international collaborations necessary to design, build and operate tomorrow’s gravitational wave observatories.

    More precise observations of the gravitational fingerprints of the most energetic phenomena in our universe may also help CERN in its quest to understand the fundamental constituents of matter. Collisions of black holes or neutron stars and supernovae explosions, for example, could shed light on open questions such as the nature of dark matter, the limits of the validity of general relativity and the behaviour of matter at extreme densities and pressures.

    “Overall, we had a healthy exchange of ideas that opened the door to the exploration of possible further synergies and joint work,” said Barish.

    See the full article here.

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    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 3:32 pm on June 15, 2017 Permalink | Reply
    Tags: , , , Black Hole Mergers, Caltech/MIT Advanced aLigo, , ,   

    From Ethan Siegel: “Newest LIGO signal raises a huge question: do merging black holes emit light?” 

    Ethan Siegel
    June 15, 2017

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    There are many cases in the Universe, such as imploding stars or neutron star collisions, that are strongly suspected of creating high-energy bursts of electromagnetic energy. Black hole mergers aren’t supposed to be one of them, but the observational data may yet surprise us. Image credit: NASA / Skyworks Digital.

    Gravitational waves and electromagnetic ones don’t need to go together. But physics says it’s possible; what do the observations say?

    “The black holes collide in complete darkness. None of the energy exploding from the collision comes out as light. No telescope will ever see the event.”
    -Janna Levin

    Billions of years ago, two black holes much more massive than the Sun — 31 and 19 solar masses each — merged together in a distant galaxy far across the Universe. On January 4th of this year, those gravitational waves, traveling through the Universe at the speed of light, finally reached Earth, where they compressed and stretched our planet by the width of no more than a few atoms. Yet that was enough for the twin LIGO detectors in Washington and Louisiana to pick up the signal and reconstruct exactly what happened. For the third time ever, we had directly detected gravitational waves. Meanwhile, telescopes and observatories all over the world, including in orbit around Earth, were looking for an entirely different signal: for some type of light, or electromagnetic radiation, that these merging black holes might have produced.

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    Illustration of two black holes merging, of comparable mass to what LIGO has seen. The expectation is that there ought to be very little in the way of an electromagnetic signal emitted from such a merger, but the presence of strongly heated matter surrounding these objects could change that. Image credit:Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project (http://www.black-holes.org).

    According to our best models of physics, merging black holes aren’t supposed to emit any light at all. A massive singularity surrounded by an event horizon might emit gravitational waves, due to the changing curvature of space time as it orbits an inspirals with another giant mass, in line with General Relativity’s predictions. Because that gravitational energy, emitted as radiation, needs to come from somewhere, the final black hole post-merger is about two solar masses lighter than the sum of the originals that created it. This is completely in line with the other two mergers LIGO observed: where around 5% of the original masses were converted into pure energy, in the form of gravitational radiation.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


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

    ESA/eLISA the future of gravitational wave research

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    The masses of known binary black hole systems, including the three verified mergers and one merger candidate coming from LIGO. Image credit: LIGO/Caltech/Sonoma State (Aurore Simonnet).

    But if there’s anything outside of those black holes, such as an accretion disk, a firewall, a hard shell, a diffuse cloud, or any other possibility, the acceleration and heating of that material could conceivably create electromagnetic radiation traveling right alongside those gravitational waves. In the aftermath of the first LIGO detection, the Fermi Gamma-ray Burst Monitor made headlines as they claimed to detect a high energy burst of radiation coincident within a second of the gravitational wave signal.

    NASA/Fermi Telescope


    NASA/Fermi LAT

    Unfortunately, ESA’s Integral satellite not only failed to confirm Fermi’s results, but scientists working there uncovered a flaw in Fermi’s analysis of their data, completely discrediting their results.

    ESA/Integral

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    Artist’s impression of two merging black holes, with accretion disks. The density and energy of the matter here should be insufficient to create gamma ray or X-ray bursts, but you never know what nature holds. Image credit: NASA / Dana Berry (Skyworks Digital).

    The second merger held no such hints of electromagnetic signals, but that was less surprising: the black holes were of significantly lower mass, so any signal arising from them would be expected to be correspondingly lower in magnitude. But the third merger was large in mass again, more comparable to the first than the second. While Fermi has made no announcement, and Integral again reports a non-detection, there are two pieces of evidence that suggest there may have been an electromagnetic counterpart after all. The AGILE satellite from the Italian Space Agency detected a weak, short-lived event that occurred just half a second before the LIGO merger, while X-ray, radio and optical observations combined to identify a strange afterglow less than 24 hours after the merger.

    Italian Space Agency AGILE Spacecraft

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    Our galaxy’s supermassive black hole has witnessed some incredibly bright flares, but none as bright or long-lasting as XJ1500+0134. These transient events and afterglows do occur for quite some time, but if they’re associated with a gravitational merger, you’d expect the arrival time of the electromagnetic and gravitational wave signals to be concurrent. Image credit: NASA/CXC/Stanford/I. Zhuravleva et al.

    If either of these were connected to the black hole merger, it would be absolutely revolutionary. There is so little we presently know about black holes in general, much less merging black holes. We’ve never directly imaged one before, although the Event Horizon Telescope hopes to grab the first later this year.

    Event Horizon Telescope Array

    Event Horizon Telescope map

    The locations of the radio dishes that will be part of the Event Horizon Telescope array. Image credit: Event Horizon Telescope sites, via University of Arizona at https://www.as.arizona.edu/event-horizon-telescope.

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment (APEX)

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    We’ve only just this year determined that black holes don’t have hard shells encircling the event horizon, and even that evidence is only statistical. So when it comes to the possibility that black holes might have an electromagnetic counterpart, it’s important to keep an open mind, to look, and to go wherever the data takes us.

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    Distant, massive quasars show ultramassive black holes in their cores, and their electromagnetic counterparts are easy to detect. But it remains to be seen whether merging black holes, particularly of these lower-mass (under 100 Suns) mergers, emit anything detectable. Image credit: J. Wise/Georgia Institute of Technology and J. Regan/Dublin City University.

    Unfortunately, neither one of these observations provide the necessary data to take us to a place where we’d conclude that merging black holes really do have a light-emitting counterpart. It’s very difficult to get compelling evidence in the first place, since even the twin LIGO detectors, operating with their incredible precision, can’t pinpoint the location of a gravitational wave signal to better accuracy than a constellation or three. Since gravitational waves and electromagnetic waves both travel at the speed of light, it’s extraordinarily unlikely that there would be nearly a 24 hour delay between a gravitational wave signal and an electromagnetic signal; in addition, that transient event appears to occur at a distance far too great to be associated with the gravitational wave event.

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    The observational field-of-view of the AGILE observatory during the moment of the LIGO observations (in color), with the possible location of the gravitational wave source shown in the magenta outlines.

    But the AGILE observations may potentially provide a hint that something interesting is going on. At the moment that the gravitational wave event occurred, AGILE was pointed at a region of space that contains 36% of the candidate LIGO region. And they do claim an “excess of detected X-ray photons” coming from somewhere on the sky over the standard, average background. But when you look at the data yourself, you have to ask yourself: how compelling is this?

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    Three critical figures, showing the raw data of the alleged ‘signal’ along with the background of X-ray emissions observed by the AGILE satellite, from the recently submitted publication, AGILE Observations of the Gravitational Wave Source GW170104.

    Over a few seconds before-and-after the LIGO merger, they pulled out an interesting event that they identify as “E2” in the three charts above. After doing a full analysis, where they account for what they saw and what sort of random fluctuations and backgrounds just naturally occur, they can conclude that there’s about a 99.9% chance that something interesting happened. In other words, that they saw an actual signal of something, rather than a random fluctuation. After all, the Universe is full of objects that emit gamma rays and X-rays, and that’s what the background is made of. But was it related to the gravitational merger of these two black holes?

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    Computer simulation of two merging black holes producing gravitational waves. The big, unanswered question is whether there will be any sort of electromagnetic, light counterpart to this signal? Image credit: Werner Benger, cc by-sa 4.0.

    If it were, you’d expect other satellites to see it. The best we can conclude, so far, is that if black holes do have an electromagnetic counterpart, it’s one that’s:

    incredibly weak,
    that occurs mostly at lower energies,
    that doesn’t have a bright optical or radio or gamma-ray component,
    and that occurs with an offset to the actual emission of gravitational waves.

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    The 30-ish solar mass binary black holes first observed by LIGO are very difficult to form without direct collapse. Now that it’s been observed twice, these black hole pairs are thought to be quite common. But the question of electromagnetic emission from these mergers is not yet settled. Image credit: LIGO, NSF, A. Simonnet (SSU).

    Also, everything we see is perfectly consistent — and arguably, more consistent — with the notion that merging black holes don’t have any electromagnetic counterparts at all. But the truth about it all is that we don’t have sufficient data to decide just yet. With more gravitational wave detectors, more black hole mergers of high masses, better pinpointing of the location, and better all-sky coverage of transient events, we just might find out the answer to this. If the missions and observatories proposed to collect this data are successfully built, operated, and (where necessary) launched, then 15 years from now, we can expect to actually know the scientific answer for certain.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 12:46 pm on June 13, 2017 Permalink | Reply
    Tags: , , , , Caltech/MIT Advanced aLigo, , intermediate Palomar Transient Factory (iPTF), iPTF17cw, These aren’t the bursts you’re looking for   

    From astrobites: “These aren’t the bursts you’re looking for” 

    Astrobites bloc

    Astrobites

    Jun 13, 2017
    Amber Hornsby

    Title: iPTF17cw: An engine-driven supernova candidate discovered independent of a gamma-ray trigger
    Authors: A. Corsi et al.
    First Author’s Institution: Department of Physics and Astronomy, Texas Tech University, Texas
    1
    Status: Submitted to the Astrophysical Journal (ApJ) , open access

    Using the intermediate Palomar Transient Factory (iPTF), a broadlined type Ic supernova (Bl-Ic SN) was accidentally uncovered during follow up observations of the newest gravitational wave in town – GW170104.

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    7

    Further investigation of iPTF17cw suggests it is the first discovery of a candidate relativistic BL-Ic SN discovered independently of a gamma ray trigger. Today’s bite presents the discovery, classification and follow-up observations of this fascinating supernova.

    Coincidence?

    On the 4th of January 2017, the ripples in space-time created by two black holes merging were detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO).


    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

    This detection resulted in a call to scientists around the world for follow-up observations, with the aim of locating an elusive electromagnetic (EM) counterpart. Observations undertaken by the extensive iPTF, a fully-automated survey measuring a region almost 40 times the size of the full moon, revealed a candidate event.

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    Figure 2: The location of iPTF17cw, indicated by the star, superimposed on the likely origin of GW170104 as determined by LIGO. Black contours indicate the 90% credible region. Figure 1 in the paper.

    Dubbed iPTF17cw, the event originated outside of the 90% localisation area of the gravitational wave, shown above in Figure 1, allowing scientists to quickly rule out the two events as being related.

    Follow-up observations

    With the gravitational wave scenario ruled out, scientists moved towards the event being a SN. At the time of its discovery this SN had a magnitude of R = 19.5 mag, but was not visible during observations of the same field taken in December. Therefore several follow-up observations of the source were made to work out what had caused this burst of energy.

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    Figure 3: Light curves created after several follow up observations of iPTF17cw. Several similar supernovae light curves are also plotted. Figure 3 in the paper.

    The authors note several interesting features in their observations including the detection of crucial narrow emission lines, such as those created by hydrogen, allowing for a redshift of z=0.093 to be calculated. Several broadline features were also observed, causing the team to classify the supernova as a type Ic SN. Type Ic SNe are a subclass of SN described as engine-driven, meaning they’re commonly associated with Gamma Ray Bursts (GRBs).

    In the gap

    GRBs are short-lived, energetic explosions of gamma-rays which are the brightest known events in the universe. Their origin, however, is not well understood, but the most likely cause is a star collapsing to form a neutron star or black hole – a supernova! GRBs are relativistic because they eject particles at speeds comparable to the speed of light; as a result, they fade on timescales of a few days, whereas the afterglow of a SN is known for its longevity, shining brightly for hundreds of years.

    The link between GRBs and broadline type Ic supernovae has been established for over twenty years, yet it is still uncertain why some supernovae emit jets of energetic particles. This jet-like behaviour is observed in the X-ray and gamma ray regime, meaning beams must be directed towards Earth to be observed. Moreover, a small portion of SNe discovered to have relativistic jets lack GRB components. It is unclear whether these events could be a new population of events that exist somewhere in the gap between SNe and GRBs, or if we’ve just missed key observations due to technological barriers. To establish whether iPTF17cw is relativistic and associated with a GRB, the team moved towards multi-wavelength observations of the surrounding area.

    Multi-wavelength observations

    Using the Very Large Array (VLA) observations of the iPTF17cw were made over a 3 month period, yielding a faint point-like radio source at 6 GHz. Because of its point-like nature, it’s unlikely to be caused by star formation occurring in the host galaxy.

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

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    Figure 4: VLA observations of iPTF17cw, red point-like source in the centre, at 6 GHz. Figure 6 in the paper.

    The team then investigated the X-ray regime with the Swift Satellite and Chandra X-ray observatory to search for counterparts, but only detected X-rays with Chandra.

    NASA/SWIFT Telescope

    NASA/Chandra Telescope

    This was not a confident detection, yet its location is consistent with the optical and radio counterparts of the burst. Next, the Fermi and Swift catalogues were searched to find possible gamma-ray counterparts. A candidate match, a gamma-ray burst lasting 30s called GRB 161228, was uncovered.

    Analysis of multi-wavelength data suggests that GRB 161228 and iPTF17cw are likely to be related. The rate of Fermi GRBs falling within the region of GRB161228 was estimated to be 0.05 per month, meaning a chance coincidence of the events occurring but not being related has a probability of around 5%.

    Is this a new kind of SN?

    Most of the conclusions drawn for this SN rely heavily on comparisons with previous events, such as similarities in light curve shown in Figure 3. There are clear agreements between the engine-driven SN1998bw and relativistic SN2009bb, which further suggest iPTF17cw and GRB161228 are related.

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    Figure 4: VLA observations of iPTF17cw at 14 GHz. No detection was found. Figure 6 in the paper.

    Finally, this SN was not detected at 14 GHz radio frequencies, suggesting that the SN is relativistic because it faded very quickly at this more energetic frequency. This 14 would put this SN in a rare category: relativistic and discovered independently of gamma-rays. Follow-up observations with the VLA are crucial to confirm iPTF17cw’s relativistic nature by confirming that the SN has also faded at lower frequencies.

    Thanks to the iPTF many more BL-Ic SNe are now being discovered, and a greater sample will greatly improve our understanding of this weird phenomenon of engine-driven SNe. In fact the team expect to collect a sample of BL-Ic SNe in a year as large as the sample that has been collected over the last five years. It is only a matter of time before scientists conclude if a GRB counterpart is required, or if we have an extra category of events existing in the SN – GRB gap.

    Further investigation of iPTF17cw suggests it is the first discovery of a candidate relativistic BL-Ic SN discovered independently of a gamma ray trigger. Today’s bite presents the discovery, classification and follow-up observations of this fascinating supernova.

    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 7:56 pm on June 9, 2017 Permalink | Reply
    Tags: Caltech/MIT Advanced aLigo, , , SDSC- San Diego Supercomputer Center,   

    From Science Node: “XSEDE cuts through the noise” 

    Science Node bloc
    Science Node

    06 June, 2017
    Alisa Alering

    3
    Courtesy LIGO; Caltech; MIT; Sonoma State; Aurore Simonnet.

    Over two billion years ago, when multicellular life had only just begun to evolve on Earth, two black holes collided and merged to form a new black hole.

    With a mass 49 times that of our sun, the massive collision set off ripples in space-time that radiated from the event like waves from a stone thrown into a pond. Predicted by Albert Einstein in 1916 and known as gravitational waves, those ripples are still traveling.


    Surf’s up! The Extreme Science and Engineering Discovery Environment (XSEDE) provides the HPC resources required to pluck gravitational waves from the noise found on LIGO detectors. Courtesy XSEDE.

    Able to pass through dust, matter, or anything else without being distorted, gravitational waves carry unique information about cosmic events that can’t be obtained in any other way. When the waves reach Earth, they give astrophysicists a completely new way to explore the universe.

    The first such waves were detected on September 14, 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific Collaboration. In the months since, two more gravitational wave events have been confirmed, one in December 2015 and the most recent on January 4, 2017.


    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

    Signal from noise

    When gravitational waves pass by, they change the distance between objects. The change is so infinitesimal that it can’t be felt, or seen with a microscope. But incredibly sensitive scientific instruments—interferometers—can detect a change that is a thousand times smaller than a proton.

    The LIGO Scientific Collaboration, a body of more than 1,000 international scientists who collectively perform LIGO research, operates two interferometers located over 2000 miles apart in Washington and Louisiana, USA.

    Despite the sensitivity of the instruments, it’s not easy to detect a gravitational wave. When a signal is received, scientists must determine what it means and how likely it is to be noise or a real gravitational wave. Making that determination requires high-performance computing.

    Since 2013, LIGO has collaborated with the Extreme Science and Engineering Discovery Environment (XSEDE), a National Science Foundation (NSF)-funded cyberinfrastructure network that includes not just high-performance computing systems but also experts who help researchers move projects forward.

    Better, faster, cheaper

    In order to validate the discovery of a gravitational wave, researchers measure the significance of the signal by calculating a false alarm rate for the event.


    Making waves, taking names. The top part of the animation shows two black holes orbiting each other until they merge, and the lower part shows the two distinct gravitational waves emitted. Thanks to supercomputers at TACC and SDSC, researchers can pick out these waves from other detector noise. Courtesy Simulating eXtreme Spacetimes collaboration.

    TACC Maverick HP NVIDIA supercomputer

    TACC Lonestar Cray XC40 supercomputer

    Dell Poweredge U Texas Austin Stampede Supercomputer. Texas Advanced Computer Center 9.6 PF

    TACC HPE Apollo 8000 Hikari supercomputer

    TACC Maverick HP NVIDIA supercomputer

    SDSC Triton HP supercomputer

    SDSC Gordon-Simons supercomputer

    SDSC Dell Comet supercomputer

    Once confirmed, further supercomputer analysis is used to extract precise estimates of the physical properties of the event, including the masses of the colliding objects, position, orientation, and distance from the Earth, carefully checking millions of combinations of these characteristics and testing how well the predicted waveform matches the signal detected by LIGO.

    To draw larger conclusions about the nature of black holes requires careful modeling based on the received data. Each simulation can take from a week to one month to complete, depending upon the complexity.

    Such intensive data analysis requires large scale high-throughput computing with parallel workflows at the scale of tens of thousands of cores for long periods of time. LIGO has been allocated millions of hours on XSEDE’s high-performance computers, including Stampede at the Texas Advanced Computing Center (TACC) and Comet at the San Diego Supercomputer Center (SDSC).

    Over the first year of XSEDE’s collaboration with LIGO, XSEDE worked to increase the speed of the applications, making them 8-10x faster on average.

    “The strategic collaboration between the two NSF-funded projects allows for accelerated scientific discovery which also translates into cost-savings for LIGO on the order of tens of millions of dollars so far,” says Pedro Marronetti, Gravitational Physics program director at the NSF.

    Waves of the future

    LIGO plans to upgrade its observatories and improve the sensitivity of its detectors before the next observational period begins in late 2018. LIGO predicts that once its observatories reach their most sensitive state, they may able to detect as many as 40 gravitational waves per year.

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    More instruments like LIGO will soon be listening for waves around the world in Italy, Japan, and India. Scientists also hope to place interferometers in orbit in order to avoid interference from Earth noise.

    And that means much more computing power will be required to verify the signals and extract information about the nature and origins of our universe.

    See the full article here .

    Please help promote STEM in your local schools.
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    Science Node is an international weekly online publication that covers distributed computing and the research it enables.

    “We report on all aspects of distributed computing technology, such as grids and clouds. We also regularly feature articles on distributed computing-enabled research in a large variety of disciplines, including physics, biology, sociology, earth sciences, archaeology, medicine, disaster management, crime, and art. (Note that we do not cover stories that are purely about commercial technology.)

    In its current incarnation, Science Node is also an online destination where you can host a profile and blog, and find and disseminate announcements and information about events, deadlines, and jobs. In the near future it will also be a place where you can network with colleagues.

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  • richardmitnick 9:19 pm on June 6, 2017 Permalink | Reply
    Tags: , , , Caltech/MIT Advanced aLigo, , Latest Black Hole Collision Comes With a Twist, ,   

    From Quanta: “Latest Black Hole Collision Comes With a Twist” 

    Quanta Magazine
    Quanta Magazine

    June 1, 2017
    Natalie Wolchover

    1
    An illustration of a newly detected black-hole merger, whose gravitational-wave signal suggests that at least one of the black holes was misaligned with its orbital motion before merging with its partner. LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

    Once again, a gust of gravitational waves coming from the faraway collision of black holes has tickled the instruments of the Advanced Laser Interferometer Gravitational-Wave Observatory (Advanced LIGO), bringing the count of definitive gravitational-wave detections up to three. The new signal, detected in January and reported today in Physical Review Letters, deepens the riddle of how black holes come to collide.


    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

    Before Advanced LIGO switched on in the fall of 2015 and almost immediately detected gravitational waves from a black-hole merger, no one knew whether it would see merging black holes, merging neutron stars, black holes merging with neutron stars or none of the above. (As Albert Einstein figured out a century ago, pairs of dense, tightly orbiting objects are needed to generate ripples in the fabric of space-time, or gravitational waves.) But the three signals spotted by LIGO so far have all come from merging black holes, suggesting pairs of these ultradense, invisible objects abundantly populate the universe.

    Astronomers have since been struggling mightily to understand how black holes (which, for the most part, are remnants of collapsed stars) can wind up so close to each other, without having been close enough to have merged during their stellar lifetimes. It’s a puzzle that has forced experts to think anew about many aspects of stars.

    They’ll now have to think even harder.

    3
    Lucy Reading-Ikkanda for Quanta Magazine

    The LIGO team’s estimate for the abundance of black-hole mergers in the universe, based on its first two detections, favored one of two competing scenarios for how stars might end up colliding as black holes: The “common-envelope” and “chemically homogeneous” scenarios both involve pairs of massive stars that form near each other in the otherwise empty expanse of space, gravitationally collapse into black holes and collide. The methods differ in their details, but either is theoretically capable of producing enough black-hole mergers to account for Advanced LIGO’s signals. Scientists think it’s likely that one scenario is dominant in the universe and accounts for almost all observed events, since it would be strange for multiple scenarios to produce equal numbers of events in a fine-tuned balance.

    Meanwhile, the high rate of mergers disfavored a third scenario called “dynamical formation,” which has the black holes forming far apart inside a dense stellar cluster. According to this theory, over time, the black holes sink to the center of the cluster, perturbing one another’s orbits in complicated ways and, occasionally, entering tight enough orbits to collide. Considering the relative rareness of stellar clusters and dynamical collisions, the expected rate associated with this scenario seemed too low to account for Advanced LIGO’s data.

    That’s where the new gravitational-wave signal comes in. It originated from black holes weighing 31 times and 19 times the mass of the sun that merged roughly 3 billion light-years away. The signal also indicates that at least one of the black holes may have been spinning in a direction that was not aligned with the pair’s common axis of rotation. Black holes that formed and evolved from a close-knit pair of stars — as in the common-envelope and chemically homogeneous scenarios — would spin in the same direction as their common axis (if at all), so misaligned spins would disfavor these scenarios and favor dynamical formation in a stellar cluster, which does not require any connection between the black holes’ spins.

    The spin measurement is difficult to do and carries some uncertainty — it’s within the margin of error that the black holes weren’t spinning at all. “We’ll need more events to be able to statistically disentangle what is happening,” said Daniel Holz, an astrophysicist at the University of Chicago and a LIGO member who has worked on the common-envelope scenario. “If it turns out that there is significant support for high misaligned spins, then we do indeed face a conundrum,” he said. “The cluster model would be favored, but it’s not straightforward for it to produce the rates we are seeing.”

    Duncan Brown, a LIGO member and professor of physics at Syracuse University, told Quanta that it might be possible after all that multiple scenarios produce black-hole mergers. But he’s waiting for more statistics. “As LIGO’s sensitivity improves — we’re still a factor of three away from design sensitivity — and as we see more signals, we’ll get a much better understanding of the spins of the black hole population. [The new signal] contains hints of something interesting, but right now I’m looking forward to future detections before making a call.”

    See the full article here .

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    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 9:41 am on May 29, 2017 Permalink | Reply
    Tags: , , , Background of gravitational waves expected from binary black hole events like GW150914, , Caltech/MIT Advanced aLigo, ,   

    From LIGO: “Background of gravitational waves expected from binary black hole events like GW150914” 

    LSC LIGO Scientific Collaboration

    LIGO Scientific Collaboration

    5.29.17 Presentation
    No writer credit found


    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

    Introduction
    It is an amazing time in the field of gravitational-wave astronomy—the observation of gravitational waves by the Advanced LIGO detectors from a binary black hole merger is an event of tremendous scientific significance. A century ago, Einstein developed general relativity and predicted the existence of gravitational waves. This first direct detection of gravitational waves, the so-called “GW150914” event, is a confirmation of Einstein’s theory and is the first direct observation of a pair of black holes merging to form a single black hole. The observation of GW150914, and future observations of binary black hole mergers, will provide new insights about massive black holes in the relatively nearby part of our Universe.

    GW150914 will not be the only event of its type in the Universe. It can be expected that, on average, binary black hole mergers occur at some rate. When these mergers happen within a couple of billion light-years from the Earth, they will likely be directly observed by Advanced LIGO (and soon to come, Advanced Virgo, and ESA eLISA). Events that are further than this will just appear as random noise in the gravitational-wave detectors (like static on an old-fashioned TV), too small to be individually directly measured. However, it will be possible to observe the sum of binary black hole mergers that have happened throughout the history of our observable Universe.

    What is a gravitational-wave background?
    Gravitational waves are ripples in spacetime predicted by Einstein’s theory of general relativity. Gravitational waves are produced by accelerating objects of any size, including us humans. Most of these waves, however, are far too weak to experimentally detect. In general, we can only hope to observe gravitational waves produced by the most massive objects moving close to the speed of light, such as the binary black holes that produced GW150914.

    For every nearby, loud event like GW150914, there are many more that are too far away to be individually detected by Advanced LIGO. The gravitational waves from these distant binary black holes instead combine to create a relatively quiet “popcorn” background of gravitational waves. As a pair of black holes merges, it produces a short burst of gravitational waves lasting just a few tenths of a second. These mostly-quiet individual bursts are separated in time, and arrive at Earth at an average rate of about one every 15 minutes. Their exact arrival times, though, are randomly distributed, just like the random popping of individual kernels of popcorn.

    A popcorn background is an example of a broader category of gravitational-wave signal called a stochastic background. In general, stochastic backgrounds are formed by the combination of many unresolvable sources. Unresolvable sources are those which we cannot distinguish individually, either because they are too quiet (as in the case of a popcorn background described above) or because there are simply too many occurring at once. Detecting a stochastic background is something like listening to voices in a crowded room. Aside from the loudest people and those standing nearest to you, you can hear the remaining conversations blend together into a continuous hum.

    What can it tell us?
    Gravitational waves are expected to have been created throughout the history of the Universe. Depending on when they were produced, gravitational-wave backgrounds can be classified into two basic categories: cosmological and astrophysical. Cosmological backgrounds are predicted to have been produced by sources that existed in the very early Universe just a few seconds after the Big Bang, while astrophysical backgrounds are predicted to have been produced by systems of massive stars such as the neutron stars and black holes that we see today. Most likely, contributions to the gravitational-wave background from astrophysical sources will dominate cosmological ones. The gravitational-wave signal produced by a population of binary black holes like GW150914 is an example of an astrophysical background.

    The strength of the gravitational-wave background at different frequencies strongly depends on the type of sources that produce them. Thus, depending on the type of gravitational-wave background we detect, we may learn about the state of the Universe just a few moments after the Big Bang or how the Universe is evolving in more recent times. In addition, looking at whether the signal is stronger from certain directions on the sky or is uniformly spread out will give us information about the distribution of the sources that produced the background.

    What does GW150914 mean for a gravitational-wave background? Why is this interesting?
    GW150914 was a single event. Its gravitational waves were from the merger of two black holes, having masses of about 29 times and 36 times the mass of the Sun, forming a single black hole with a mass of about 62 times the Sun’s mass. The large component masses of the black holes making up GW150914 suggest that the unresolved popcorn signal from the population of binary black holes is probably stronger than most astrophysicists originally thought. This means we have a better chance of measuring this background with the Advanced LIGO and Virgo detectors. We will have to analyze the data for several years, but it may be possible to eventually measure the signal.

    How do we detect these gravitational waves?
    Although the individual signals from the binary black hole mergers have a characteristic shape, the signals from distant sources will be too weak to be individually detected and the arrival times of the popcorn-like bursts will be random. This means that the standard searches that look for single events like GW150914 won’t work for detecting the relatively quiet popcorn signal from the population of binary black hole mergers throughout the Universe. So we need to take a different approach (described below) to detect the waves from these unresolvable sources.

    It is hard to search for a weak random signal using data from a single detector because the detector noise itself is also random. So instead we compare (“correlate”) data from pairs of detectors, e.g., the two LIGO detectors in Hanford, WA and Livingston, LA. The random gravitational-wave signal will be the same (“correlated”) in both detectors, while the detector noise will not (since the detectors are widely separated and most noise sources due to the environment are local to the detectors). Thus we can use this similarity (“correlation”) to distinguish the gravitational-wave signal from unwanted detector noise.

    Moreover, by performing this correlation over the whole duration of the run (which could be months or years), we build up the signal relative to the noise by including the contribution of the events that occur (on average) once every 15 minutes. The more data we have to analyze, the better it is for this type of search.

    Estimating the gravitational-wave background based on what we’ve learned from GW150914
    A number of factors contribute to how many binary black hole systems will form in the Universe. An important long-term research question will be to try and describe how systems like GW150914 were created. For example, maybe the two original black holes in GW150914 evolved from a binary star system, where the two stars orbiting one another were very massive. Or perhaps the system was created in a globular cluster (a group of stars tightly bound together by gravity) where one could imagine many interactions taking place that would make initially small black holes evolve into larger ones. The most massive stars are short-lived and often produce black holes upon their death, so knowing the birth rate of massive stars is important. Star formation rates depend on the amount of matter present, and its constituents; was there just hydrogen and helium present when the star was formed, or were there other elements as well? Also, how long did the two black holes take to get close enough to collide? All of these ingredients contribute to the different binary black hole formation models that we considered.

    If we detect a stochastic gravitational-wave background in the future, we will not be able to distinguish between different models describing how these binary black hole systems were created. We will, however, be able to contribute to understanding how often these mergers happen in the far away Universe. Future measurements of individual mergering black holes will provide a better estimate of how often these types of events take place in the nearby Universe and more information on the masses of the black holes. Combining what we learn from a stochastic background with measurements from individual events may help distinguish between different formation pathways for binary black holes.

    Implications for the future
    The GW150914 event suggests that merger rates and masses of binary black holes are on the high end of the range of earlier predictions. This means that a gravitational-wave background due to merging black holes is expected to be larger as well. There are sizable uncertainties associated with the strength of this background, but detecting it may be within reach of the advanced detectors at their peak sensitivity. Looking to the future, the next generation of gravitational-wave detectors might be able combine measurements of a gravitational-wave background with measurements of individual black hole mergers to distinguish how black holes may come to orbit one another.

    Glossary

    Astrophysical background A stochastic background of gravitational waves produced by sources such as neutron stars and black holes.
    Black hole A region of space-time caused by an extremely compact mass where the gravity is so intense it prevents anything, including light, from leaving.
    Correlation The amount of similarity between two sets of data. For example, the comparison of data from pairs of gravitational-wave detectors in order to search for weak signals (like a stochastic background) that are shared (“correlated”) between the two instruments.
    Cosmological background A stochastic background of gravitational waves produced by sources such as those in the very early Universe in the instant after the Big Bang.
    Globular cluster A very dense group of stars bound together by gravity.
    Neutron star An extremely dense object which remains after the collapse of a massive star.
    Popcorn background The combination effects of bursts of gravitational waves from all binary black holes too distant to be directly observed. These bursts arrive at Earth at random times, like the popping of individual kernels of corn.
    Spacetime An interwoven continuum of space and time.
    Stochastic background A gravitational-wave signal formed from the combination of many individually unresolvable sources. Sources are unresolvable if they are too weak to be directly observed or if too many overlap at once, like conversations in a loud, crowded room.
    Stochastic Randomly determined; having a random pattern that may be analyzed statistically but may not be predicted precisely.

    Read more:

    Freely readable preprint of the publication describing the analysis
    Data used for this analysis
    Advanced LIGO
    Advanced Virgo

    See the full article here .

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    About the LSC

    The LIGO Scientific Collaboration (LSC) is a group of scientists seeking to make the first direct detection of gravitational waves, use them to explore the fundamental physics of gravity, and develop the emerging field of gravitational wave science as a tool of astronomical discovery. The LSC works toward this goal through research on, and development of techniques for, gravitational wave detection; and the development, commissioning and exploitation of gravitational wave detectors.

    The LSC carries out the science of the LIGO Observatories, located in Hanford, Washington and Livingston, Louisiana as well as that of the GEO600 detector in Hannover, Germany. Our collaboration is organized around three general areas of research: analysis of LIGO and GEO data searching for gravitational waves from astrophysical sources, detector operations and characterization, and development of future large scale gravitational wave detectors.

    Founded in 1997, the LSC is currently made up of more than 1000 scientists from dozens of institutions and 15 countries worldwide. A list of the participating universities.

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

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

    VIRGO Gravitational Wave interferometer, near Pisa, Italy
    VIRGO Gravitational Wave interferometer, near Pisa, Italy

     
  • richardmitnick 4:40 pm on May 28, 2017 Permalink | Reply
    Tags: , , , Caltech/MIT Advanced aLigo, , , ,   

    From Monash: “Monash University researchers uncover new Gravitational Waves characteristics” 

    Monash Univrsity bloc

    Monash University

    23 May 2017

    1
    A visualization of a supercomputer simulation of merging black holes sending out gravitational waves. Credit: NASA/C. Henze/phys.org

    Monash University researchers have identified a new concept – ‘orphan memory’ – which changes the current thinking around gravitational waves.

    The research, by the Monash Centre for Astrophysics, was published recently in Physical Review Letters.

    Einstein’s theory of general relativity predicts that cataclysmic cosmic explosions stretch the fabric of spacetime.

    The stretching of spacetime is called ‘gravitational waves.’ After such an event, spacetime does not return to its original state. It stays stretched out. This effect is called ‘memory.’

    The term ‘orphan’ alludes to the fact that the parent wave is not directly detectable.

    “These waves could open the way for studying physics currently inaccessible to our technology,” said Monash School of Physics and Astronomy Lecturer, Dr Eric Thrane, one of the authors of the study, together with Lucy McNeill and Dr Paul Lasky.

    “This effect, called ‘memory’ has yet to be observed,” said Dr Thrane.

    Gravitational-wave detectors such as LIGO only ‘hear’’ gravitational waves at certain frequencies, explains lead author Lucy McNeill.


    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

    “If there are exotic sources of gravitational waves out there, for example, from micro black holes, LIGO would not hear them because they are too high-frequency,” she said.

    “But this study shows LIGO can be used to probe the universe for gravitational waves that were once thought to be invisible to it.”

    Study co-author Dr Lasky said LIGO won’t be able to see the oscillatory stretching and contracting, but it will be able to detect the memory signature if such objects exist.

    The researchers were able to show that high-frequency gravitational waves leave behind a memory that LIGO can detect.

    “This realisation means that LIGO [or e/Lisa] may be able to detect sources of gravitational waves that no one thought it could,” said Dr Lasky.

    See the full article here .

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    Monash U campus

    Monash University (/ˈmɒnæʃ/) is an Australian public research university based in Melbourne, Australia. Founded in 1958, it is the second oldest university in the State of Victoria. Monash is a member of Australia’s Group of Eight and the ASAIHL, and is the only Australian member of the influential M8 Alliance of Academic Health Centers, Universities and National Academies. Monash is one of two Australian universities to be ranked in the The École des Mines de Paris (Mines ParisTech) ranking on the basis of the number of alumni listed among CEOs in the 500 largest worldwide companies.[6] Monash is in the top 20% in teaching, top 10% in international outlook, top 20% in industry income and top 10% in research in the world in 2016.[7]

    Monash enrolls approximately 47,000 undergraduate and 20,000 graduate students,[8] It also has more applicants than any university in the state of Victoria.

    Monash is home to major research facilities, including the Australian Synchrotron, the Monash Science Technology Research and Innovation Precinct (STRIP), the Australian Stem Cell Centre, 100 research centres[9] and 17 co-operative research centres. In 2011, its total revenue was over $2.1 billion, with external research income around $282 million.[10]

    The university has a number of centres, five of which are in Victoria (Clayton, Caulfield, Berwick, Peninsula, and Parkville), one in Malaysia.[11] Monash also has a research and teaching centre in Prato, Italy,[12] a graduate research school in Mumbai, India[13] and a graduate school in Jiangsu Province, China.[14] Since December 2011, Monash has had a global alliance with the University of Warwick in the United Kingdom.[15] Monash University courses are also delivered at other locations, including South Africa.

    The Clayton campus contains the Robert Blackwood Hall, named after the university’s founding Chancellor Sir Robert Blackwood and designed by Sir Roy Grounds.[16]

    In 2014, the University ceded its Gippsland campus to Federation University.[17] On 7 March 2016, Monash announced that it would be closing the Berwick campus by 2018.

     
  • richardmitnick 12:57 pm on May 25, 2017 Permalink | Reply
    Tags: , , , Caltech/MIT Advanced aLigo, , , N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey, , , NGC 6946 Fireworks Galaxy, SN 2017eaw   

    From Hubble: “Collapsing Star Gives Birth to a Black Hole” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    May 25, 2017
    Christopher Kochanek / Krzysztof Stanek
    Ohio State University, Columbus, Ohio
    614-292-5954 / 614-292-3433
    kochanek.1@osu.edu / stanek.32@osu.edu

    Scott Adams
    Caltech, Pasadena, California
    626-395-8676
    smadams@caltech.edu

    Pam Frost Gorder
    Ohio State University, Columbus, Ohio
    614-292-9475
    gorder.1@osu.edu

    Elizabeth Landau
    Jet Propulsion Laboratory, Pasadena, California
    818-354-6425
    elizabeth.r.landau@jpl.nasa.gov

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    1
    Massive Dying Star Goes Out With a Whimper Instead of a Bang

    Every second a star somewhere out in the universe explodes as a supernova. But some super-massive stars go out with a whimper instead of a bang. When they do, they can collapse under the crushing tug of gravity and vanish out of sight, only to leave behind a black hole. The doomed star, named N6946-BH1, was 25 times as massive as our sun. It began to brighten weakly in 2009. But, by 2015, it appeared to have winked out of existence. By a careful process of elimination, based on observations by the Large Binocular Telescope and the Hubble and Spitzer space telescopes, the researchers eventually concluded that the star must have become a black hole. This may be the fate for extremely massive stars in the universe.

    U Arizona Large Binocular Telescope, Mount Graham, Arizona, USA

    Astronomers have watched as a massive, dying star was likely reborn as a black hole. It took the combined power of the Large Binocular Telescope (LBT), and NASA’s Hubble and Spitzer space telescopes to go looking for remnants of the vanquished star, only to find that it disappeared out of sight.

    NASA/Spitzer Telescope

    It went out with a whimper instead of a bang.

    The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out—and then left behind a black hole.

    “Massive fails” like this one in a nearby galaxy could explain why astronomers rarely see supernovae from the most massive stars, said Christopher Kochanek, professor of astronomy at The Ohio State University and the Ohio Eminent Scholar in Observational Cosmology.

    As many as 30 percent of such stars, it seems, may quietly collapse into black holes — no supernova required.

    “The typical view is that a star can form a black hole only after it goes supernova,” Kochanek explained. “If a star can fall short of a supernova and still make a black hole, that would help to explain why we don’t see supernovae from the most massive stars.”

    He leads a team of astronomers who published their latest results in the Monthly Notices of the Royal Astronomical Society.

    Among the galaxies they’ve been watching is NGC 6946, a spiral galaxy 22 million light-years away that is nicknamed the “Fireworks Galaxy” because supernovae frequently happen there — indeed, SN 2017eaw, discovered on May 14th, is shining near maximum brightness now. Starting in 2009, one particular star, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence.

    After the LBT survey for failed supernovas turned up the star, astronomers aimed the Hubble and Spitzer space telescopes to see if it was still there but merely dimmed. They also used Spitzer to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud.

    All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole.

    It’s too early in the project to know for sure how often stars experience massive fails, but Scott Adams, a former Ohio State student who recently earned his Ph.D. doing this work, was able to make a preliminary estimate.

    “N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we’ve been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae,” he said.

    “This is just the fraction that would explain the very problem that motivated us to start the survey, that is, that there are fewer observed supernovae than should be occurring if all massive stars die that way.”

    To study co-author Krzysztof Stanek, the really interesting part of the discovery is the implications it holds for the origins of very massive black holes — the kind that the LIGO experiment detected via gravitational waves. (LIGO is the Laser Interferometer Gravitational-Wave Observatory.)


    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

    It doesn’t necessarily make sense, said Stanek, professor of astronomy at Ohio State, that a massive star could undergo a supernova — a process which entails blowing off much of its outer layers — and still have enough mass left over to form a massive black hole on the scale of those that LIGO detected.

    “I suspect it’s much easier to make a very massive black hole if there is no supernova,” he concluded.

    Adams is now an astrophysicist at Caltech. Other co-authors were Ohio State doctoral student Jill Gerke and University of Oklahoma astronomer Xinyu Dai. Their research was supported by the National Science Foundation.

    NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington, D.C. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

    The Large Binocular Telescope is an international collaboration among institutions in the United Sates, Italy and Germany.

    See the full article here .
    See the JPL-Caltech full article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

    AURA Icon

    NASA image

     
  • richardmitnick 10:51 am on May 22, 2017 Permalink | Reply
    Tags: Caltech/MIT Advanced aLigo, Hubble detects a supermassive black hole ejected from the galactic core,   

    From Manu Garcia: “Hubble detects a supermassive black hole ejected from the galactic core” 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    22/5/17
    Manu Garcia

    1
    The picture:
    The galaxy 3C186 , located about 8 billion light years from Earth is most likely the result of a merger of two galaxies. This is supported by the tidal tails arcuate generally produced by a gravitational pull between two colliding galaxies, identified by scientists. Merging galaxies also led to a fusion of the two supermassive black holes at their centers and the resulting black hole was expelled from its parent galaxy by gravitational waves created by the merger. The bright quasar, like a star, you can see in the center of the image. His previous host galaxy is the faint object, extended behind him. Photo credit: NASA, ESA, M. Chiaberge (STScI / ESA)

    An international team of astronomers using the Hubble Space Telescope has discovered a supermassive black hole that has been driven out of the center of the distant galaxy 3C186 .

    NASA/ESA Hubble Telescope

    The black hole was probably driven by the power of gravitational waves. This is the first time astronomers have found a supermassive black hole at such a great distance from its host galaxy ‘s center.

    Although other fugitives suspected black holes have been seen elsewhere, so far none has been confirmed. Now astronomers using the Hubble Space Telescope , NASA / ESA have detected a supermassive black hole with a mass a billion times the Sun, being expelled from its parent galaxy. ” We estimate that took the energy equivalent of 100 million supernovas exploding simultaneously to get rid of the black hole” describes Stefano Bianchi, co-author of the study, the Roma Tre University, Italy.

    Images taken by Hubble provided the first clue that the galaxy called 3C186 , was unusual. The images of the galaxy, located to 8 billion light years away, revealed a bright quasar, the energy signature of an active black hole located far from the galactic core. “Black holes reside at the centers of galaxies, so it is rare to see a quasar that is not in the center of the galaxy , ” says the team leader, Marco Chiaberge researcher ESA-AURA at the Institute of Sciences Space telescope, United States .

    The team calculated that the black hole has already traveled about 35,000 light years from the center of the host galaxy, it is more than the distance between the Sun and the center of the Milky Way. He continues his flight at a speed of 7.5 million kilometers per hour [1]. At this speed the black hole could travel from Earth to the moon in three minutes.

    Although we can not exclude other scenarios to explain the observations, the most plausible source of propulsive power is that this massive black hole was kicked gravity wave [2] triggered by the fusion of two massive black holes at the center of its host galaxy. This theory is supported by tidal tails arcuate identified by scientists, produced by a gravitational pull between two colliding galaxies.

    According to the theory presented by scientists, it is estimated that 2 billion years ago between 1 or two galaxies each with a central supermassive black hole merged. Black holes turned around each other in the center of the newly formed elliptical galaxy, creating gravitational waves that were dropped as water a lawn sprinkler [3]. As the two black holes did not have the same mass and rotational speed, gravitational waves emitted most strongly along one direction. When two black holes eventually merged, the anisotropic emission of gravitational waves generated kick that fired the resulting black hole outside the galactic center.

    “If our theory is correct, the observations provide strong evidence that supermassive black holes can merge,” says Stefano Bianchi on the importance of the discovery. “There is already evidence of black hole collisions for black holes of stellar mass, but the process that regulates supermassive black holes is more complex and still not fully understood.”

    Researchers are lucky enough to have captured this unique event because not all mergers of black holes produce gravitational waves unbalanced propelling a black hole outside the galaxy. The computer now want to secure a longer observation time with the Hubble , in combination with the Atacama Large Millimeter / submillimeter Array (ALMA) and other facilities, to more accurately measure the speed of the black hole and its disk surrounding gas within the nature of this rare object.

    notes:
    [1] As the black hole can not be observed directly, the mass and velocity of supermassive black holes were determined through spectroscopic analysis of its surrounding gas.

    [2] first predicted by Albert Einstein , gravitational waves are ripples in space which are created by the acceleration of massive objects. The corrugations are similar to concentric circles produced when a rock is thrown in a pond. In 2016, the Gravitational Wave Observatory ( LIGO ) helped astronomers to prove that there are detecting gravitational waves emanating from the merger of two black holes of stellar mass, which are several times more massive than the sun.


    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

    [3] The black holes approach with time as radiating gravitational energy.

    See the full article here .

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