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  • richardmitnick 1:54 pm on January 18, 2022 Permalink | Reply
    Tags: "There are 40 billion billions of Black Holes in the Universe!", A remarkable amount-around 1% of the overall ordinary (baryonic) matter of the Universe-is locked up in stellar mass black holes., , , , , , How many black holes are out there in the Universe? This is one of the most relevant and pressing questions in modern astrophysics and cosmology., Multi-messenger astrophysics, , With a new computational approach SISSA researchers have been able to make the fascinating calculation.   

    From The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati](IT): “There are 40 billion billions of Black Holes in the Universe!” 

    1

    From The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati](IT)

    1.18.22

    Nico Pitrelli
    pitrelli@sissa.it
    T +39 040 3787462
    M +39 339 1337950

    Donato Ramani
    ramani@sissa.it
    T +39 040 3787513
    M +39 342 8022237

    There are 40 billion billions of Black Holes in the Universe!

    1
    Image by PIxabay

    With a new computational approach SISSA researchers have been able to
    make the fascinating calculation. Moreover, according to their work, around
    1% of the overall ordinary (baryonic) matter is locked up in stellar mass
    black holes. Their results have just been published in the prestigious The
    Astrophysical Journal
    .

    How many black holes are out there in the Universe? This is one of the most
    relevant and pressing questions in modern astrophysics and cosmology. The
    intriguing issue has recently been addressed by the SISSA Ph.D. student Alex
    Sicilia, supervised by Prof. Andrea Lapi and Dr. Lumen Boco, together with other
    collaborators from SISSA and from other national and international institutions. In
    a first paper of a series just published in The Astrophysical Journal, the authors have investigated the demographics of stellar mass black holes, which are black
    holes with masses between a few to some hundred solar masses, that originated
    at the end of the life of massive stars. According to the new research, a
    remarkable amount around 1% of the overall ordinary (baryonic) matter of
    the Universe is locked up in stellar mass black holes. Astonishingly, the
    researchers have found that the number of black holes within the
    observable Universe (a sphere of diameter around 90 billions light years) at
    present time is about 40 trillions, 40 billion billions (i.e., about 40 x 1018, i.e.
    4 followed by 19 zeros!).

    A new method to calculate the number of black holes

    As the authors of the research explain: “This important result has been obtained
    thanks to an original approach which combines the state-of-the-art stellar and
    binary evolution code SEVN developed by SISSA researcher Dr. Mario Spera to
    empirical prescriptions for relevant physical properties of galaxies, especially the
    rate of star formation, the amount of stellar mass and the metallicity of the
    interstellar medium (which are all important elements to define the number and
    the masses of stellar black holes). Exploiting these crucial ingredients in a self-
    consistent approach, thanks to their new computation approach, the researchers
    have then derived the number of stellar black holes and their mass distribution
    across the whole history of the Universe. Alex Sicilia, first author of the study,
    comments: “The innovative character of this work is in the coupling of a detailed
    model of stellar and binary evolution with advanced recipes for star formation and
    metal enrichment in individual galaxies. This is one of the first, and one of the
    most robust, ab initio computation of the stellar black hole mass function across
    cosmic history.”

    What’s the origin of most massive stellar black holes?

    The estimate of the number of black holes in the observable Universe is not the
    only issue investigated by the scientists in this piece of research. In collaboration
    with Dr. Ugo Di Carlo and Prof. Michela Mapelli from The University of Padua [Università degli Studi di Padova](IT),they
    have also explored the various formation channels for black holes of different
    masses, like isolated stars, binary systems and stellar clusters. According to their
    work, the most massive stellar black holes originate mainly from dynamical
    events in stellar clusters. Specifically, the researchers have shown that such
    events are required to explain the mass function of coalescing black holes as
    estimated from gravitational wave observations by the LIGO/Virgo collaboration.

    Caltech/MIT Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    Lumen Boco, co-author of the paper, comments: “Our work provides a robust
    theory for the generation of light seeds for (super)massive black holes at high
    redshift, and can constitute a starting point to investigate the origin of ‘heavy
    seeds’, that we will pursue in a forthcoming paper.

    A multidisciplinary work carried out in the context of “BiD4BESt – Big Data
    Application for Black Hole Evolution Studies”

    Prof. Andrea Lapi, Sicilia’s supervisor and coordinator of the Ph.D. in
    Astrophysics and Cosmology at SISSA, adds: “This research is really
    multidisciplinary, covering aspects of, and requiring expertise in stellar
    astrophysics, galaxy formation and evolution, gravitational wave and multi-messenger astrophysics; as such it needs collaborative efforts from various
    members of the SISSA Astrophysics and Cosmology group, and a strong
    networking with external collaborators.”

    Alex Sicilia’s work occurs in the context of a prestigious Innovative Training
    Network Project “BiD4BESt – Big Data Application for Black Hole Evolution
    Studies” co-PIed by Prof. Andrea Lapi from SISSA (H2020-MSCAITN-2019
    Project 860744), that has been funded by the European Union with about 3.5
    million Euros overall; it involves several academic and industrial partners, to
    provide Ph.D. training to 13 early stage researchers in the area of black hole
    formation and evolution, by exploiting advanced data science techniques.

    See the full article here.

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    2
    International School for Advanced Studies, Trieste. Credit: Mike Peel (http://www.mikepeel.net)

    The International School for Advanced Studies [Scuola Internazionale Superiore di Studi Avanzati] (IT) (SISSA) is an international, state-supported, post-graduate-education and research institute, located in Trieste, Italy.

    SISSA is active in the fields of mathematics, physics, and neuroscience, offering both undergraduate and post-graduate courses. Each year, about 70 PhD students are admitted to SISSA based on their scientific qualifications. SISSA also runs master’s programs in the same areas, in collaboration with both Italian and other European universities.

    History

    SISSA was founded in 1978, as a part of the reconstruction following the Friuli earthquake of 1976. Although the city of Trieste itself did not suffer any damage, physicist Paolo Budinich asked and obtained from the Italian government to include in the interventions the institution of a new, post-graduate teaching and research institute, modeled on the Scuola Normale Superiore di Pisa(IT). The school became operative with a PhD course in theoretical physics, and Budinich himself was appointed as general director. In 1986, Budinich left his position to Daniele Amati, who at the time was at the head of the theoretical division at The European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire](CH)[CERN]. Under his leadership, SISSA expanded its teaching and research activity towards the field of neuroscience, and instituted a new interdisciplinary laboratory aiming at connecting humanities and scientific studies. From 2001 to 2004, the director was the Italian geneticist Edoardo Boncinelli, who fostered the development of the existing research areas. Other directors were appointed in the following years, which saw the strengthening of SISSA collaboration with other Italian and European universities in offering master’s degree programs in the three areas of the School (mathematics, physics and neuroscience). The physicist Stefano Ruffo, the current director, was appointed in 2015. He signed a partnership with the International Centre for Genetic Engineering and Biotechnology to set up a new PhD program in Molecular Biology, with teaching activity organized by both institutions.

    Organization

    SISSA houses the following research groups:

    Astroparticle Physics
    Astrophysics
    Condensed Matter
    Molecular and Statistical Biophysics
    Statistical Physics
    Theoretical Particle Physics
    Cognitive Neuroscience
    Neurobiology
    Molecular Biology
    Applied Mathematics
    Geometry
    Mathematical Analysis
    Mathematical Physics

    In addition, there is the Interdisciplinary Laboratory for Natural and Humanistic Sciences (now LISNU – Laboratorio Interdisciplinare Scienze Naturali e Umanistiche), which is endowed with the task of making connections between science, humanities, and the public. It currently offers a course in Scientific Communication and Scientific journalism.

    SISSA also enjoys special teaching and scientific links with the International Centre for Theoretical Physics, the International Centre for Genetic Engineering and Biotechnology and the Elettra Synchrotron Light Laboratory.

     
  • richardmitnick 9:26 am on October 30, 2021 Permalink | Reply
    Tags: "Taming The Data Deluge", , , , , , Brain imaging neuroscience, , , , , , , Multi-messenger astrophysics, , , ,   

    From Kavli MIT Institute For Astrophysics and Space Research : “Taming The Data Deluge” 

    KavliFoundation

    http://www.kavlifoundation.org/institutes

    MIT Kavli Institute for Astrophysics and Space Research.

    From Kavli MIT Institute For Astrophysics and Space Research

    October 29, 2021

    Sandi Miller | Department of Physics

    An oncoming tsunami of data threatens to overwhelm huge data-rich research projects on such areas that range from the tiny neutrino to an exploding supernova, as well as the mysteries deep within the brain.

    2
    Left to right: Erik Katsavounidis of MIT’s Kavli Institute, Philip Harris of the Department of Physics, and Song Han of the Department of Electrical Engineering and Computer Science are part of a team from nine institutions that secured $15 million in National Science Foundation funding to set up the Accelerated AI Algorithms for Data-Driven Discovery (A3D3) Institute. Photo: Sandi Miller.

    When LIGO picks up a gravitational-wave signal from a distant collision of black holes and neutron stars, a clock starts ticking for capturing the earliest possible light that may accompany them: time is of the essence in this race.

    Caltech /MIT Advanced aLigo

    Data collected from electrical sensors monitoring brain activity are outpacing computing capacity. Information from the Large Hadron Collider (LHC)’s smashed particle beams will soon exceed 1 petabit per second.

    To tackle this approaching data bottleneck in real-time, a team of researchers from nine institutions led by The University of Washington (US), including The Massachusetts Institute of Technology (US), has received $15 million in funding to establish the Accelerated AI Algorithms for Data-Driven Discovery (A3D3) Institute. From MIT, the research team includes Philip Harris, assistant professor of physics, who will serve as the deputy director of the A3D3 Institute; Song Han, assistant professor of electrical engineering and computer science, who will serve as the A3D3’s co-PI; and Erik Katsavounidis, senior research scientist with the MIT Kavli Institute for Astrophysics and Space Research.

    Infused with this five-year Harnessing the Data Revolution Big Idea grant, and jointly funded by the Office of Advanced Cyberinfrastructure, A3D3 will focus on three data-rich fields: multi-messenger astrophysics, high-energy particle physics, and brain imaging neuroscience. By enriching AI algorithms with new processors, A3D3 seeks to speed up AI algorithms for solving fundamental problems in collider physics, neutrino physics, astronomy, gravitational-wave physics, computer science, and neuroscience.

    “I am very excited about the new Institute’s opportunities for research in nuclear and particle physics,” says Laboratory for Nuclear Science Director Boleslaw Wyslouch. “Modern particle detectors produce an enormous amount of data, and we are looking for extraordinarily rare signatures. The application of extremely fast processors to sift through these mountains of data will make a huge difference in what we will measure and discover.”

    The seeds of A3D3 were planted in 2017, when Harris and his colleagues at DOE’s Fermi National Accelerator Laboratory (US) and The European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN] decided to integrate real-time AI algorithms to process the incredible rates of data at the LHC. Through email correspondence with Han, Harris’ team built a compiler, HLS4ML, that could run an AI algorithm in nanoseconds.

    “Before the development of HLS4ML, the fastest processing that we knew of was roughly a millisecond per AI inference, maybe a little faster,” says Harris. “We realized all the AI algorithms were designed to solve much slower problems, such as image and voice recognition. To get to nanosecond inference timescales, we recognized we could make smaller algorithms and rely on custom implementations with Field Programmable Gate Array (FPGA) processors in an approach that was largely different from what others were doing.”

    A few months later, Harris presented their research at a physics faculty meeting, where Katsavounidis became intrigued. Over coffee in Building 7, they discussed combining Harris’ FPGA with Katsavounidis’s use of machine learning for finding gravitational waves. FPGAs and other new processor types, such as graphics processing units (GPUs), accelerate AI algorithms to more quickly analyze huge amounts of data.

    “I had worked with the first FPGAs that were out in the market in the early ’90s and have witnessed first-hand how they revolutionized front-end electronics and data acquisition in big high-energy physics experiments I was working on back then,” recalls Katsavounidis. “The ability to have them crunch gravitational-wave data has been in the back of my mind since joining LIGO over 20 years ago.”

    Two years ago they received their first grant, and the University of Washington’s Shih-Chieh Hsu joined in. The team initiated the Fast Machine Lab, published about 40 papers on the subject, built the group to about 50 researchers, and “launched a whole industry of how to explore a region of AI that has not been explored in the past,” says Harris. “We basically started this without any funding. We’ve been getting small grants for various projects over the years. A3D3 represents our first large grant to support this effort.”

    “What makes A3D3 so special and suited to MIT is its exploration of a technical frontier, where AI is implemented not in high-level software, but rather in lower-level firmware, reconfiguring individual gates to address the scientific question at hand,” says Rob Simcoe, director of MIT Kavli Institute for Astrophysics and Space Research and the Francis Friedman Professor of Physics. “We are in an era where experiments generate torrents of data. The acceleration gained from tailoring reprogrammable, bespoke computers at the processor level can advance real-time analysis of these data to new levels of speed and sophistication.”

    The Huge Data from the Large Hadron Collider

    With data rates already exceeding 500 terabits per second, the LHC processes more data than any other scientific instrument on earth. Its future aggregate data rates will soon exceed 1 petabit per second, the biggest data rate in the world.

    “Through the use of AI, A3D3 aims to perform advanced analyses, such as anomaly detection, and particle reconstruction on all collisions happening 40 million times per second,” says Harris.

    The goal is to find within all of this data a way to identify the few collisions out of the 3.2 billion collisions per second that could reveal new forces, explain how Dark Matter is formed, and complete the picture of how fundamental forces interact with matter. Processing all of this information requires a customized computing system capable of interpreting the collider information within ultra-low latencies.

    “The challenge of running this on all of the 100s of terabits per second in real-time is daunting and requires a complete overhaul of how we design and implement AI algorithms,” says Harris. “With large increases in the detector resolution leading to data rates that are even larger the challenge of finding the one collision, among many, will become even more daunting.”

    The Brain and the Universe

    Thanks to advances in techniques such as medical imaging and electrical recordings from implanted electrodes, neuroscience is also gathering larger amounts of data on how the brain’s neural networks process responses to stimuli and perform motor information. A3D3 plans to develop and implement high-throughput and low-latency AI algorithms to process, organize, and analyze massive neural datasets in real time, to probe brain function in order to enable new experiments and therapies.

    With Multi-Messenger Astrophysics (MMA), A3D3 aims to quickly identify astronomical events by efficiently processing data from gravitational waves, gamma-ray bursts, and neutrinos picked up by telescopes and detectors.

    The A3D3 researchers also include a multi-disciplinary group of 15 other researchers, including project lead the University of Washington, along with The California Institute of Technology (US), Duke University (US), Purdue University (US), The University of California-San Diego (US), The University of Illinois-Urbana-Champaign (US), The University of Minnesota (US), and The University of Wisconsin-Madison (US). It will include neutrinos research at The University of Wisconsin IceCube Neutrino Observatory(US) and The Fermi National Accelerator Laboratory DUNE/LBNF experiment (US), and visible astronomy at The Zwicky Transient Facility (US), and will organize deep-learning workshops and boot camps to train students and researchers on how to contribute to the framework and widen the use of fast AI strategies.

    “We have reached a point where detector network growth will be transformative, both in terms of event rates and in terms of astrophysical reach and ultimately, discoveries,” says Katsavounidis. “‘Fast’ and ‘efficient’ is the only way to fight the ‘faint’ and ‘fuzzy’ that is out there in the universe, and the path for getting the most out of our detectors. A3D3 on one hand is going to bring production-scale AI to gravitational-wave physics and multi-messenger astronomy; but on the other hand, we aspire to go beyond our immediate domains and become the go-to place across the country for applications of accelerated AI to data-driven disciplines.”

    Science paper:
    Hardware-accelerated Inference for Real-Time Gravitational-Wave Astronomy

    See the full article here .


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    Mission Statement

    The mission of the MIT Kavli Institute (MKI) for Astrophysics and Space Research is to facilitate and carry out the research programs of faculty and research staff whose interests lie in the broadly defined area of astrophysics and space research. Specifically, the MKI will

    Provide an intellectual home for faculty, research staff, and students engaged in space- and ground-based astrophysics
    Develop and operate space- and ground-based instrumentation for astrophysics
    Engage in technology development
    Maintain an engineering and technical core capability for enabling and supporting innovative research
    Communicate to students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of MKI’s research.

    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

    To date, The Kavli Foundation has made grants to establish Kavli Institutes on the campuses of 20 major universities. In addition to the Kavli Institutes, nine Kavli professorships have been established: three at Harvard University, two at University of California, Santa Barbara, one each at University of California, Los Angeles, University of California, Irvine, Columbia University, Cornell University, and California Institute of Technology.

    The Kavli Institutes:

    The Kavli Foundation’s 20 institutes focus on astrophysics, nanoscience, neuroscience and theoretical physics.

    Astrophysics

    The Kavli Institute for Particle Astrophysics and Cosmology at Stanford University
    The Kavli Institute for Cosmological Physics, University of Chicago
    The Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology
    The Kavli Institute for Astronomy and Astrophysics at Peking University
    The Kavli Institute for Cosmology at the University of Cambridge
    The Kavli Institute for the Physics and Mathematics of the Universe at the University of Tokyo

    Nanoscience

    The Kavli Institute for Nanoscale Science at Cornell University
    The Kavli Institute of Nanoscience at Delft University of Technology in the Netherlands
    The Kavli Nanoscience Institute at the California Institute of Technology
    The Kavli Energy NanoSciences Institute at University of California, Berkeley and the Lawrence Berkeley National Laboratory
    The Kavli Institute for NanoScience Discovery at the University of Oxford

    Neuroscience

    The Kavli Institute for Brain Science at Columbia University
    The Kavli Institute for Brain & Mind at the University of California, San Diego
    The Kavli Institute for Neuroscience at Yale University
    The Kavli Institute for Systems Neuroscience at the Norwegian University of Science and Technology
    The Kavli Neuroscience Discovery Institute at Johns Hopkins University
    The Kavli Neural Systems Institute at The Rockefeller University
    The Kavli Institute for Fundamental Neuroscience at the University of California, San Francisco

    Theoretical physics

    Kavli Institute for Theoretical Physics at the University of California, Santa Barbara
    The Kavli Institute for Theoretical Physics China at the University of Chinese Academy of Sciences

     
  • richardmitnick 9:05 am on February 27, 2020 Permalink | Reply
    Tags: , , , , , Multi-messenger astrophysics,   

    From ARC Centres of Excellence for Gravitational Wave Discovery via phys.org: “Future space detector LISA could reveal the secret life and death of stars” 

    arc-centers-of-excellence-bloc

    From ARC Centres of Excellence for Gravitational Wave Discovery

    via


    phys.org

    1
    Artist’s illustration of an ‘isolated neutron star’—one without associated supernova remnants, binary companions or radio pulsations. Credit: Casey Reed – Penn State University

    A team of astrophysicists led by Ph.D. student Mike Lau, from the ARC Centre of Excellence in Gravitational Wave Discovery (OzGrav), recently predicted that gravitational waves of double neutron stars may be detected by the future space satellite LISA. The results were presented at the 14th annual Australian National Institute for Theoretical Astrophysics (ANITA) science workshop 2020. These measurements may help decipher the life and death of stars.

    Lau, first author of the paper, compares his team to astro-paleontologists: “Like learning about a dinosaur from its fossil, we piece together the life of a binary star from their double neutron star fossils.”

    A neutron star is the remaining ‘corpse’ of a huge star after the supernova explosion that occurs at the end of its life. A double neutron star, a system of two neutron stars orbiting each other, produces periodic disturbances in the surrounding space-time, much like ripples spreading on a pond surface. These ‘ripples’ are called gravitational waves, and made headlines when the LIGO/Virgo Collaboration detected them for the first time in 2015. These gravitational waves formed when a pair of black holes spiraled too close together and merged.

    However, scientists still haven’t found a way to measure the gravitational waves given off when two neutron stars or black holes are still far apart in their orbit. These weaker waves hold valuable information about the lives of stars and could reveal the existence of entirely new object populations in our Galaxy.

    The recent study [below] shows that the Laser Interferometer Space Antenna (LISA) could potentially detect these gravitational waves from double neutron stars.

    ESA/NASA eLISA

    ESA/NASA eLISA space based, the future of gravitational wave research

    LISA is a space-borne gravitational-wave detector that is scheduled for launch in 2034, as part of a mission led by the European Space Agency. It’s made of three satellites linked by laser beams, forming a triangle that will orbit the Sun. Passing gravitational waves will stretch and squeeze the 40 million-kilometer laser arms of this triangle. The highly sensitive detector will pick up the slowly-oscillating waves—these are currently undetectable by LIGO and Virgo.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Using computer simulations to model a population of double neutron stars, the team predicts that in four years of operation, LISA will have measured the gravitational waves emitted by dozens of double neutron stars as they orbit each other. Their results were published in the Monthly Notices of the Royal Astronomical Society.

    A supernova explosion kicks the neutron star it forms and makes the initial circular orbit oval-shaped. Usually, gravitational wave emission rounds off the orbit—that is the case for double neutron stars detected by LIGO and Virgo. But LISA will be able to detect double neutron stars when they’re still far apart, so it may be possible to catch a glimpse of the oval orbit.

    How oval the orbit is, described as the eccentricity of the orbit, can tell astronomers a lot about what the two stars looked like before they became double neutron stars. For example, their separation and how strongly they were ‘kicked’ by the supernova.

    The understanding of binary stars—stars that are born as a pair—is plagued with many uncertainties. Scientists hope that by the 2030s, LISA’s detection of double neutron stars will shed some light on their secret lives.

    See the full article here .

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    About Science X in 100 words
    Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
    Mission 12 reasons for reading daily news on Science X Organization Key editors and writersinclude 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

    OzGrav

    THE ARC CENTRE of excellence FOR GRAVITATIONAL WAVE DISCOVERY
    A new window of discovery.
    A new age of gravitational wave astronomy.
    One hundred years ago, Albert Einstein produced one of the greatest intellectual achievements in physics, the theory of general relativity. In general relativity, spacetime is dynamic. It can be warped into a black hole. Accelerating masses create ripples in spacetime known as gravitational waves (GWs) that carry energy away from the source. Recent advances in detector sensitivity led to the first direct detection of gravitational waves in 2015. This was a landmark achievement in human discovery and heralded the birth of the new field of gravitational wave astronomy. This was followed in 2017 by the first observations of the collision of two neutron-stars. The accompanying explosion was subsequently seen in follow-up observations by telescopes across the globe, and ushered in a new era of multi-messenger astronomy.

    The mission of the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) is to capitalise on the historic first detections of gravitational waves to understand the extreme physics of black holes and warped spacetime, and to inspire the next generation of Australian scientists and engineers through this new window on the Universe.

    OzGrav is funded by the Australian Government through the Australian Research Council Centres of Excellence funding scheme, and is a partnership between Swinburne University (host of OzGrav headquarters), the Australian National University, Monash University, University of Adelaide, University of Melbourne, and University of Western Australia, along with other collaborating organisations in Australia and overseas.

    ________________________________________________________

    The objectives for the ARC Centres of Excellence are to to:

    undertake highly innovative and potentially transformational research that aims to achieve international standing in the fields of research envisaged and leads to a significant advancement of capabilities and knowledge
    link existing Australian research strengths and build critical mass with new capacity for interdisciplinary, collaborative approaches to address the most challenging and significant research problems
    develope relationships and build new networks with major national and international centres and research programs to help strengthen research, achieve global competitiveness and gain recognition for Australian research
    build Australia’s human capacity in a range of research areas by attracting and retaining, from within Australia and abroad, researchers of high international standing as well as the most promising research students
    provide high-quality postgraduate and postdoctoral training environments for the next generation of researchers
    offer Australian researchers opportunities to work on large-scale problems over long periods of time
    establish Centres that have an impact on the wider community through interaction with higher education institutes, governments, industry and the private and non-profit sector.

     
  • richardmitnick 1:52 pm on February 22, 2020 Permalink | Reply
    Tags: , , , , Black Hole convergence, , LIGO/VIRO, Multi-messenger astrophysics   

    From AAS NOVA: “Gravitational Waves After Galaxy Collisions” 

    AASNOVA

    From AAS NOVA

    21 February 2020
    Susanna Kohler

    1
    A new study explores whether the collision of very small galaxies could lead to the merging black holes detected in gravitational waves. [NASA/ESA]

    Thanks to the Laser Interferometer Gravitational-wave Observatory (LIGO), we now know that black holes in our distant universe sometimes find each other in a dramatic inspiral and collision, releasing a burst of gravitational-wave emission that we can detect here on Earth.

    But what happened earlier in these black holes’ lives to bring them to this point? A new study explores the possibility that LIGO’s black holes once lay at the centers of very small galaxies — until those galaxies collided.

    2
    Simulated iconic image of two merging black holes, viewed face-on. LIGO has announced the detection of ten of these events so far. [SXS Lensing]

    Central Lurkers

    Since we discovered the first wiggles in spacetime signifying the distant merger of two black holes, LIGO has announced around ten confident detections of gravitational waves from black hole–black hole collisions — with the prospect of many more discoveries in the future.

    Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2018

    But how did these black holes find each other? A team of scientists led by Christopher Conselice (University of Nottingham, UK) has proposed a picture that hinges on the central black holes we believe lie at the heart of most, if not all, galaxies.

    The team proposes that very low-mass dwarf galaxies contain central black holes of less than 100 solar masses. The mergers of pairs of these tiny galaxies ultimately lead to the inspirals and mergers of their central black holes — possibly accounting for the majority of LIGO’s detections of black hole–black hole collisions.

    Testing Feasibility

    Conselice and collaborators test this scenario by breaking it down into multiple steps.

    4
    The relationship between black hole mass and host galaxy stellar mass (black solid line; blue dashed lines show uncertainties), extrapolated down to low masses. Red lines indicate the masses of LIGO-detected black holes. [Conselice et al. 2020]

    1.Can you get central black holes of the right mass?
    We’ve observed a relationship between galaxy mass and central black hole mass. By extrapolating this relationship to low masses, we find that ultradwarf galaxies can have central black holes of less than 100 solar masses — consistent with the LIGO-observed black holes of 10–70 solar masses.
    2. Will these ultradwarf galaxies merge frequently enough?
    Mergers of galaxies occurred more frequently in the early universe than they do today. Cosmological models indicate that galaxies don’t merge frequently enough today to reproduce LIGO’s observations — but at a redshift of z ~ 1.5 or higher, ultradwarf galaxies could merge often enough to match LIGO-measured gravitational-wave event rates.
    3.Will the black holes collide fast enough after the galaxies merge?
    If the galaxies merged at a redshift of z > 1.5, the central black holes would have to sink to the middle of the merger, inspiral, and collide on timescales of 6–8 billion years to match LIGO observations. This is feasible if the black holes are embedded in a massive star cluster at the galaxy center.

    A Future Hunt for Hosts

    Conselice and collaborators’ calculations show that merging ultradwarf galaxies in the distant universe could, conceivably, account for LIGO’s black hole–black hole merger detections.

    5
    An example of a dwarf spheroidal galaxy. The smallest dwarfs are far too faint to detect at high redshifts with current technology. [ESO/Digitized Sky Survey 2]

    In the future, we can hope to test this theory by better pinpointing the hosts of gravitational-wave events. If we find that the black-hole collisions all originate from bright, massive galaxies, then the ultradwarf-merger theory is out. But if we can’t spot the hosts, this might be because they’re ultradwarfs that are too small and faint to detect.

    The field of gravitational-wave astronomy is still only just coming of age, and theoretical work like this study shows how just how much we can hope to learn in the future!

    Citation

    “LIGO/Virgo Sources from Merging Black Holes in Ultradwarf Galaxies,” Christopher J. Conselice et al 2020 ApJ 890 8.
    https://iopscience.iop.org/article/10.3847/1538-4357/ab5dad

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 7:40 am on January 20, 2020 Permalink | Reply
    Tags: "Astronomers Detect a Burst of Gravitational Waves From The Direction of Betelgeuse", , , , , , , Multi-messenger astrophysics   

    From MIT Caltech Advanced aLIGO via Science Alert: “Astronomers Detect a Burst of Gravitational Waves From The Direction of Betelgeuse” 

    MIT Caltech Caltech Advanced aLigo new bloc

    From MIT Caltech Advanced aLIGO

    via

    ScienceAlert

    Science Alert

    1
    Betelgeuse captured in 2010. (Rogelio Bernal Andreo/Wikimedia Commons/CC BY-SA 3.0)

    20 JAN 2020
    EVAN GOUGH

    Gravitational waves [below] are caused by calamitous events in the Universe. Neutron stars that finally merge after circling each other for a long time can create them, and so can two black holes that collide with each other. But sometimes there’s a burst of gravitational waves that doesn’t have a clear cause.

    One such burst was detected by LIGO/VIRGO on January 14, and it came from the same region of sky that hosts the star Betelgeuse. Yeah, Betelgeuse, aka Alpha Orionis. The star that has been exhibiting some dimming behaviour recently, and is expected to go supernova at some point in the future.

    Might the two be connected?

    Betelgeuse is a red supergiant star in the constellation Orion. It left the main sequence about one million years ago and has been a red supergiant for about 40,000 years. Eventually, Betelgeuse will have burned enough of its hydrogen that its core will collapse, and it will explode as a supernova.

    Recently, Betelgeuse dimmed. That set off all kinds of speculation that it might be getting ready to go supernova. Astrophysicists quickly poured water on that idea. There’s no exact number, but it’s estimated that Betelgeuse won’t go supernova for another 100,000 years. But when a star dims, there’s clearly something going on.

    Is this new burst of gravitational waves connected to Betelgeuse’s recent dimming? To its future supernova explosion?

    Astronomers understand that Betelgeuse is a variable star, and its brightness can fluctuate. Stars like Betelgeuse aren’t just static entities. It’s a semi-regular variable star that shows both periodic and non-periodic changes in its brightness.

    The kind of gravitational waves that LIGO detected are called burst waves. It’s possible that a supernova could produce them, but Betelgeuse hasn’t gone supernova and won’t for a long time.

    Some think that the detection of gravitational waves in Betelgeuse’s direction is unrelated to the star itself. In fact, the detection of the burst waves may not have even been real.

    Christopher Berry is an astrophysicist studying gravitational waves at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics.

    On Twitter he spoke up about the gravitational burst waves.

    Andy Howell from Las Cumbres Observatory studies supernova and dark energy. He had something to say on Twitter too, and appeared to be having fun with the whole thing. He even walked outside to check up on Betelgeuse after the detection of the burst gravitational waves.

    3

    So there you have it. No supernova for now, anyway. The burst gravitational waves may just be a glitch, and Betelgeuse’s dimming is well-understood and not a threat.

    One day Betelgeuse will explode, and our night sky will change forever. But for us here on Earth, that supernova poses no problem.

    An exploding star is an awesome event. And it produces a cataclysm of deadly radiation. X-rays, ultraviolet radiation, and even stellar material are ejected with great force. The deadliest radiation is gamma rays, and Betelgeuse likely won’t even produce any of those when it blows.

    But in any case, we’re about 700 light years away from Betelgeuse, and that’s way too much distance for us to worry.

    The biggest fallout is that the Orion constellation will change forever. And there’ll be a new object to study in the sky: a supernova remnant.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    See the full article here .

    The Collaborations

    LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available at https://my.ligo.org/census.php.

    The Virgo collaboration consists of more than 300 physicists and engineers belonging to 28 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; 11 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in the Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with IFAE and the Universities of Valencia and Barcelona; two in Belgium with the Universities of Liege and Louvain; Jena University in Germany; and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef. A list of the Virgo Collaboration can be found at http://public.virgo-gw.eu/the-virgo-collaboration/. More information is available on the Virgo website at http://www.virgo-gw.eu.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    ESA/eLISA the future of gravitational wave research

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

     
  • richardmitnick 2:12 pm on January 7, 2020 Permalink | Reply
    Tags: "LIGO-Virgo Network Catches Another Neutron Star Collision", , , , , , , , Multi-messenger astrophysics   

    From MIT Caltech Advanced aLIGO and Advanced Virgo: “LIGO-Virgo Network Catches Another Neutron Star Collision” 

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    From MIT Caltech Advanced aLIGO and Advanced Virgo

    January 6, 2020

    Caltech
    Whitney Clavin
    wclavin@caltech.edu

    MIT
    Abigail Abazorius
    abbya@mit.edu
    617-253-2709

    Virgo
    Livia Conti
    livia.conti@pd.infn.it

    NSF
    Josh Chamot
    jchamot@nsf.gov
    703-292-4489

    1
    Artist’s rendition of two colliding neutron stars. Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

    On April 25, 2019, the LIGO Livingston Observatory picked up what appeared to be gravitational ripples from a collision of two neutron stars. LIGO Livingston is part of a gravitational-wave network that includes LIGO (the Laser Interferometer Gravitational-wave Observatory), funded by the National Science Foundation (NSF), and the European Virgo detector. Now, a new study confirms that this event was indeed likely the result of a merger of two neutron stars. This would be only the second time this type of event has ever been observed in gravitational waves.

    The first such observation, which took place in August of 2017, made history for being the first time that both gravitational waves and light were detected from the same cosmic event. The April 25 merger, by contrast, did not result in any light being detected. However, through an analysis of the gravitational-wave data alone, researchers have learned that the collision produced an object with an unusually high mass.

    “From conventional observations with light, we already knew of 17 binary neutron star systems in our own galaxy and we have estimated the masses of these stars,” says Ben Farr, a LIGO team member based at the University of Oregon. “What’s surprising is that the combined mass of this binary is much higher than what was expected.”

    “We have detected a second event consistent with a binary neutron star system and this is an important confirmation of the August 2017 event that marked an exciting new beginning for multi-messenger astronomy two years ago,” says Jo van den Brand, Virgo Spokesperson and professor at Maastricht University, and Nikhef and VU University Amsterdam in the Netherlands. Multi-messenger astronomy occurs when different types of signals are witnessed simultaneously, such as those based on gravitational waves and light.

    The study, submitted to The Astrophysical Journal Letters, is authored by an international team comprised of the LIGO Scientific Collaboration and the Virgo Collaboration, the latter of which is associated with the Virgo gravitational-wave detector in Italy. The results were presented at a press briefing today, January 6, at the 235th meeting of the American Astronomical Society in Honolulu, Hawaii.

    One of two science papers:
    GW190425

    On January 6, 2020, the LIGO Scientific Collaboration and the Virgo Collaboration announced the discovery of a second binary neutron star merger, labeled GW190425. This is the first confirmed gravitational-wave detection based on data from a single observatory. No electromagnetic counterpart was found. This system is notable for having a total mass that exceeds that of known galactic neutron star binaries.
    Publications & Documents

    Publication: GW190425: Observation of a compact binary coalescence with total mass ∼3.4 Msun

    The other paper hasn’t been accepted or published yet and may be a while.

    Neutron stars are the remnants of dying stars that undergo catastrophic explosions as they collapse at the end of their lives. When two neutron stars spiral together, they undergo a violent merger that sends gravitational shudders through the fabric of space and time.

    LIGO became the first observatory to directly detect gravitational waves in 2015; in that instance, the waves were generated by the fierce collision of two black holes. Since then, LIGO and Virgo have registered dozens of additional candidate black hole mergers.

    The August 2017 neutron star merger was witnessed by both LIGO detectors, one in Livingston, Louisiana, and one in Hanford, Washington, together with a host of light-based telescopes around the world (neutron star collisions produce light, while black hole collisions are generally thought not to do so). This merger was not clearly visible in the Virgo data, but that fact provided key information that ultimately pinpointed the event’s location in the sky.

    The April 2019 event was first identified in data from the LIGO Livingston detector alone. The LIGO Hanford detector was temporarily offline at the time, and, at a distance of more than 500 million light-years, the event was too faint to be visible in Virgo’s data. Using the Livingston data, combined with information derived from Virgo’s data, the team narrowed the location of the event to a patch of sky more than 8,200 square degrees in size, or about 20 percent of the sky. For comparison, the August 2017 event was narrowed to a region of just 16 square degrees, or 0.04 percent of the sky.

    “This is our first published event for a single-observatory detection,” says Caltech’s Anamaria Effler, a scientist who works at LIGO Livingston. “But Virgo made a valuable contribution. We used information about its non-detection to tell us roughly where the signal must have originated from.”

    The LIGO data reveal that the combined mass of the merged bodies is about 3.4 times the mass of our sun. In our galaxy, known binary neutron star systems have combined masses up to only 2.9 times that of sun. One possibility for the unusually high mass is that the collision took place not between two neutron stars, but a neutron star and a black hole, since black holes are heavier than neutron stars. But if this were the case, the black hole would have to be exceptionally small for its class. Instead, the scientists believe it is much more likely that LIGO witnessed a shattering of two neutron stars.

    “What we know from the data are the masses, and the individual masses most likely correspond to neutron stars. However, as a binary neutron star system, the total mass is much higher than any of the other known galactic neutron star binaries,” says Surabhi Sachdev, a LIGO team member based at Penn State. “And this could have interesting implications for how the pair originally formed.”

    Neutron star pairs are thought to form in two possible ways. They might form from binary systems of massive stars that each end their lives as neutron stars, or they might arise when two separately formed neutron stars come together within a dense stellar environment. The LIGO data for the April 25 event do not indicate which of these scenarios is more likely, but they do suggest that more data and new models are needed to explain the merger’s unexpectedly high mass.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    See the full article here .

    The Collaborations

    LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available at https://my.ligo.org/census.php.

    The Virgo collaboration consists of more than 300 physicists and engineers belonging to 28 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; 11 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in the Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with IFAE and the Universities of Valencia and Barcelona; two in Belgium with the Universities of Liege and Louvain; Jena University in Germany; and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef. A list of the Virgo Collaboration can be found at http://public.virgo-gw.eu/the-virgo-collaboration/. More information is available on the Virgo website at http://www.virgo-gw.eu.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    ESA/eLISA the future of gravitational wave research

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

     
  • richardmitnick 10:17 am on December 29, 2019 Permalink | Reply
    Tags: , , , , , , Multi-messenger astrophysics, ,   

    From particlebites: “Dark Photons in Light Places” 

    particlebites bloc

    From particlebites

    December 29, 2019
    Amara McCune

    Title: “Searching for dark photon dark matter in LIGO O1 data”

    Author: Huai-Ke Guo, Keith Riles, Feng-Wei Yang, & Yue Zhao

    Reference: https://www.nature.com/articles/s42005-019-0255-0

    There is very little we know about dark matter save for its existence.

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

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

    Coma cluster via NASA/ESA Hubble

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


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


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

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

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

    Dark Matter Research

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

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

    CMB per ESA/Planck

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

    Dark Matter Particle Explorer China

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

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


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

    Its mass(es), its interactions, even the proposition that it consists of particles at all is mostly up to the creativity of the theorist. For those who don’t turn to modified theories of gravity to explain the gravitational effects on galaxy rotation and clustering that suggest a massive concentration of unseen matter in the universe (among other compelling evidence), there are a few more widely accepted explanations for what dark matter might be. These include weakly-interacting massive particles (WIMPS), primordial black holes, or new particles altogether, such as axions or dark photons.

    In particle physics, this latter category is what’s known as the “hidden sector,” a hypothetical collection of quantum fields and their corresponding particles that are utilized in theorists’ toolboxes to help explain phenomena such as dark matter. In order to test the validity of the hidden sector, several experimental techniques have been concocted to narrow down the vast parameter space of possibilities, which generally consist of three strategies:

    1.Direct detection: Detector experiments look for low-energy recoils of dark matter particle collisions with nuclei, often involving emitted light or phonons.
    2.Indirect detection: These searches focus on potential decay products of dark matter particles, which depends on the theory in question.
    3.Collider production: As the name implies, colliders seek to produce dark matter in order to study its properties. This is reliant on the other two methods for verification.

    The first detection of gravitational waves from a black hole merger in 2015 ushered in a new era of physics, in which the cosmological range of theory-testing is no longer limited to the electromagnetic spectrum.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

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

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

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/NASA eLISA space based, the future of gravitational wave research

    Bringing LIGO (the Laser Interferometer Gravitational-Wave Observatory) to the table, proposals for the indirect detection of dark matter via gravitational waves began to spring up in the literature, with implications for primordial black hole detection or dark matter ensconced in neutron stars. Yet a new proposal, in a paper by Guo et. al., [Scientific Reports-Communication Physics] suggests that direct dark matter detection with gravitational waves may be possible, specifically in the case of dark photons.

    Dark photons are hidden sector particles in the ultralight regime of dark matter candidates. Theorized as the gauge boson of a U(1) gauge group, meaning the particle is a force-carrier akin to the photon of quantum electrodynamics, dark photons either do not couple or very weakly couple to Standard Model particles in various formulations. Unlike a regular photon, dark photons can acquire a mass via the Higgs mechanism. Since dark photons need to be non-relativistic in order to meet cosmological dark matter constraints, we can model them as a coherently oscillating background field: a plane wave with amplitude determined by dark matter energy density and oscillation frequency determined by mass. In the case that dark photons weakly interact with ordinary matter, this means an oscillating force is imparted. This sets LIGO up as a means of direct detection due to the mirror displacement dark photons could induce in LIGO detectors.

    3
    Figure 1: The experimental setup of the Advanced LIGO interferometer. We can see that light leaves the laser and is reflected between a few power recycling mirrors (PR), split by a beam splitter (BS), and bounced between input and end test masses (ITM and ETM). The entire system is mounted on seismically-isolated platforms to reduce noise as much as possible. Source: https://arxiv.org/pdf/1411.4547.pdf

    LIGO consists of a Michelson interferometer, in which a laser shines upon a beam splitter which in turn creates two perpendicular beams. The light from each beam then hits a mirror, is reflected back, and the two beams combine, producing an interference pattern. In the actual LIGO detectors, the beams are reflected back some 280 times (down a 4 km arm length) and are split to be initially out of phase so that the photodiode detector should not detect any light in the absence of a gravitational wave. A key feature of gravitational waves is their polarization, which stretches spacetime in one direction and compresses it in the perpendicular direction in an alternating fashion. This means that when a gravitational wave passes through the detector, the effective length of one of the interferometer arms is reduced while the other is increased, and the photodiode will detect an interference pattern as a result.

    LIGO has been able to reach an incredible sensitivity of one part in 10^{23} in its detectors over a 100 Hz bandwidth, meaning that its instruments can detect mirror displacements up to 1/10,000th the size of a proton. Taking advantage of this number, Guo et. al. demonstrated that the differential strain (the ratio of the relative displacement of the mirrors to the interferometer’s arm length, or h = \Delta L/L) is also sensitive to ultralight dark matter via the modeling process described above. The acceleration induced by the dark photon dark matter on the LIGO mirrors is ultimately proportional to the dark electric field and charge-to-mass ratio of the mirrors themselves.

    Once this signal is approximated, next comes the task of estimating the background. Since the coherence length is of order 10^9 m for a dark photon field oscillating at order 100 Hz, a distance much larger than the separation between the LIGO detectors at Hanford and Livingston (in Washington and Louisiana, respectively), the signals from dark photons at both detectors should be highly correlated. This has the effect of reducing the noise in the overall signal, since the noise in each of the detectors should be statistically independent. The signal-to-noise ratio can then be computed directly using discrete Fourier transforms from segments of data along the total observation time. However, this process of breaking up the data, known as “binning,” means that some signal power is lost and must be corrected for.

    4
    Figure 2: The end result of the Guo et. al. analysis of dark photon-induced mirror displacement in LIGO. Above we can see a plot of the coupling of dark photons to baryons as a function of the dark photon oscillation frequency. We can see that over further Advanced LIGO runs, up to O4-O5, these limits are expected to improve by several orders of magnitude. Source: https://www.nature.com/articles/s42005-019-0255-0

    In applying this analysis to the strain data from the first run of Advanced LIGO, Guo et. al. generated a plot which sets new limits for the coupling of dark photons to baryons as a function of the dark photon oscillation frequency. There are a few key subtleties in this analysis, primarily that there are many potential dark photon models which rely on different gauge groups, yet this framework allows for similar analysis of other dark photon models. With plans for future iterations of gravitational wave detectors, further improved sensitivities, and many more data runs, there seems to be great potential to apply LIGO to direct dark matter detection. It’s exciting to see these instruments in action for discoveries that were not in mind when LIGO was first designed, and I’m looking forward to seeing what we can come up with next!

    Learn More:

    An overview of gravitational waves and dark matter: https://www.symmetrymagazine.org/article/what-gravitational-waves-can-say-about-dark-matter
    A summary of dark photon experiments and results: https://physics.aps.org/articles/v7/115
    Details on the hardware of Advanced LIGO: https://arxiv.org/pdf/1411.4547.pdf
    A similar analysis done by Pierce et. al.: https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.121.061102

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    What is ParticleBites?

    ParticleBites is an online particle physics journal club written by graduate students and postdocs. Each post presents an interesting paper in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

    The papers are accessible on the arXiv preprint server. Most of our posts are based on papers from hep-ph (high energy phenomenology) and hep-ex (high energy experiment).

    Why read ParticleBites?

    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. With each brief ParticleBite, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in particle physics.

    Who writes ParticleBites?

    ParticleBites is written and edited by graduate students and postdocs working in high energy physics. Feel free to contact us if you’re interested in applying to write for ParticleBites.

    ParticleBites was founded in 2013 by Flip Tanedo following the Communicating Science (ComSciCon) 2013 workshop.

    2
    Flip Tanedo UCI Chancellor’s ADVANCE postdoctoral scholar in theoretical physics. As of July 2016, I will be an assistant professor of physics at the University of California, Riverside

    It is now organized and directed by Flip and Julia Gonski, with ongoing guidance from Nathan Sanders.

     
  • richardmitnick 7:37 am on October 30, 2019 Permalink | Reply
    Tags: "NSF invests in cyberinfrastructure institute to harness cosmic data", Cyberinfrastructure, Multi-messenger astrophysics, SCIMMA-Scalable Cyberinfrastructure Institute for Multi-Messenger Astrophysics, ,   

    From University of Washington: “NSF invests in cyberinfrastructure institute to harness cosmic data” 

    U Washington

    From University of Washington

    The National Science Foundation awarded the University of Wisconsin-Milwaukee and nine collaborating organizations, including the University of Washington, $2.8 million for a two-year “conceptualization phase” of the Scalable Cyberinfrastructure Institute for Multi-Messenger Astrophysics.

    1
    The night sky at Palouse Falls in southeastern Washington.Mark Stone/University of Washington

    SCIMMA’s goal is to develop algorithms, databases and computing and networking cyberinfrastructure to help scientists interpret multi-messenger observations. Multi-messenger astrophysics combines observations of light, gravitational waves and particles to understand some of the most extreme events in the universe. For example, the observation of both gravitational waves and light from the collision of two neutron stars in 2017 helped explain the origin of heavy elements, allowed an independent measurement of the expansion of the universe and confirmed the association between neutron-star mergers and gamma-ray bursts.

    The institute would facilitate global collaborations, thus transcending the capabilities of any single existing institution or team. It is directed by Patrick Brady, a professor of physics at the University of Wisconsin-Milwaukee and director of the Center for Gravitation, Cosmology and Astrophysics. One of three co-principal investigators on the project is Mario Jurić, a UW associate professor of astronomy and senior data science fellow at the UW eScience Institute.

    As part of SCIMMA, UW researchers will work to develop a “transient alert” system that will alert researchers around the world about cosmic events picked up, for example, by astronomical observatories.

    “These events could include phenomena like collisions between black holes and neutron stars detected via gravitational waves, exploding supernovae detected by neutrino emissions, and other energetic phenomena detected in visible wavelengths of light,” said Jurić, who is also a faculty member with the UW DIRAC Institute. “UW researchers have demonstrated these technologies as part of the Zwicky Transient Facility project, where the UW-built ZTF Alert Distribution System transmitted more than 100 million alerts over the past two years.”

    Zwicky Transient Facility (ZTF) instrument installed on the 1.2m diameter Samuel Oschin Telescope at Palomar Observatory in California. Courtesy Caltech Optical Observatories

    Caltech Palomar Samuel Oschin 48 inch Telescope, located in San Diego County, California, United States, altitude 1,712 m (5,617 ft)

    W researchers will also help develop a prototype remote analysis platform, which will allow scientists to analyze archived multi-messenger astrophysics using future resources provided by SCIMMA, said Jurić.

    SCIMMA’s two-year conceptualization phase began Sept. 1. Among its goals are enabling seamless co-analysis of disparate datasets by supporting the interoperability of software and data services. In addition, over the next two years SCIMMA will develop education and training curricula designed to enhance the STEM workforce, according to an announcement by the NSF.

    “Multi-messenger astrophysics is a data-intensive science in its infancy that is already transforming our understanding of the universe,” said Brady. “The promise of multi-messenger astrophysics, however, can be realized only if sufficient cyberinfrastructure is available to rapidly handle, combine and analyze the very large-scale distributed data from all types of astronomical measurements. The conceptualization phase of SCIMMA will balance rapid prototyping, novel algorithm development and software sustainability to accelerate scientific discovery over the next decade and more.”

    Additional project collaborators include Columbia University; the Center for Advanced Computing and Department of Astronomy at Cornell University; Las Cumbres Observatory, a California-based network of observatories; Michigan State University; Pennsylvania State University; the University of California, Santa Barbara; the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign; and the Texas Advanced Computing Center at the University of Texas at Austin.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    u-washington-campus
    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
    So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 9:49 am on October 2, 2019 Permalink | Reply
    Tags: , , , Collision between a black hole and a neutron star?, , , Multi-messenger astrophysics,   

    From Symmetry: “Chasing gravitational waves” 

    Symmetry Mag
    From Symmetry<

    10/01/19
    Diana Kwon

    1
    A. Tonita, L. Rezzolla/Goethe University of Frankfurt​, &​ F. Pannarale/Sapienza University of Rome

    When LIGO and Virgo detected the echoes that likely came from a collision between a black hole and a neutron star, dozens of physicists began a hunt for the signal’s electromagnetic counterpart.

    Around mid-afternoon on August 14, a pulse passed simultaneously through the laser beams of three enormous gravitational-wave detectors, the twin locations of the Laser Interferometer Gravitational-Wave Observatory, or LIGO, in Louisiana and Washington, and the Virgo detector in Italy.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Almost immediately, alerts beeped smartphones, tablets and laptops to life around the globe. Many of the physicists who saw this notification immediately dropped what they were doing and dashed to their computers to investigate.

    What they soon hoped to find was the first optical evidence that they were detecting a collision between a black hole and a neutron star.

    Scientists may have detected violent collision between neutron star, black hole

    An ear on the universe

    All objects with mass—including stars, planets and even humans—emit gravitational waves when they change speed or direction. But most gravitational waves are much too weak to detect. Even highly sensitive instruments like LIGO and Virgo, which are akin to microphones that hear signals from all directions, can only identify very “loud” gravitational waves caused by exceptionally massive objects that are accelerating rapidly.

    So far, the gravitational waves detected have all come from compact binaries, or two massive objects spiraling around and smashing into one another. There are three different types of pairings in a compact binary—two black holes, two neutron stars, or a neutron star and a black hole.

    Since black holes are more massive than neutron stars, their clashes generate the loudest gravitational waves. Because of this, they are the easiest to find. After their first two observing runs, the LIGO-Virgo collaboration announced official detections of 10 colliding black hole pairs.

    Neutron star-neutron star mergers, called kilonovae, are the quietest of the three. In October 2017, scientists announced the first observation of such a collision.

    It was the first successful use of LIGO-Virgo in multi-messenger astronomy, in which cosmological phenomena are examined through multiple types of signals, such as gravitational waves and electromagnetic sources like X-rays, radio waves and light.

    LIGO and Virgo send out an alert each time they hear an interesting signal to allow scientists at other observatories to immediately point their instruments at the spot in the sky where the signal most likely originated to collect as much data as possible about the source.

    The alert that went out after the neutron star merger mobilized scientists at telescopes around the world, including the DECam, a US Department of Energy-funded instrument mounted onto the National Science Foundation-funded 4-meter Blanco Telescope in Chile; the Very Large Array in New Mexico; and the Fermi Gamma-Ray Space Telescope orbiting our planet. Together, their observations helped provide evidence for a long-standing hypothesis that heavy elements such as gold and uranium were formed in the cosmic explosions that occur when two neutron stars crash.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Timeline of the Inflationary Universe WMAP

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

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

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

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

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    “That event was unbelievably exciting and scientifically rich,” says Daniel Holz, an astrophysicist at the University of Chicago and a member of both LIGO and DES-GW. “The thrill of being part of that was incredible.”

    LIGO and Virgo have released dozens of public alerts about potential detections since the beginning of their third observing run this April. To date, these include potential observations of 20 binary black holes, 4 binary neutron stars, and 2 neutron star-black holes—but none of the these has been seen with a separate electromagnetic signal.

    Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2018

    Masses in the Stellar Graveyard LIGO Virgo| Frank Elavsky | Northwestern

    The alerts are sent out almost immediately after the detectors pick up on a promising signal. In addition to identifying the potential candidate and its location on the sky, the notifications include a false alarm rate that portrays the likelihood that the proposed event was real. As researchers conduct further analyses on the data, the collaboration publishes updated estimates. If the signal turns out to be mere noise, they release a retraction.

    A needle in a haystack

    After the alert this August, the Slack channel for DES-GW, a group of scientists who use DECam to search for the optical counterparts of gravitational waves, was abuzz with chatter.

    At first, the gravitational wave was only classified as a “mass gap” detection, a signal from a pair of objects that was between the mass of the lightest black hole and the heaviest neutron star. This suggested the gravitational wave came from a new type of source, says Antonella Palmese, a postdoc at Fermilab and a member of DES-GW. But it could have been a merger between two unusually small black holes, in which case, it would be invisible to an instrument like DECam.

    After further analysis of the gravitational wave data, LIGO and Virgo scientists were able to categorize the signal as most likely a clash between a black hole and a neutron star. Although the collaboration hasn’t yet announced an official detection, their alert classified the event with greater than 99% confidence. It was their clearest gravitational-wave signal from a black hole-neutron star merger yet.

    “The moment when we got really excited and were all over our laptops was when we received the classification that it was a black hole-neutron star merger,” Palmese says. “In that case, you might expect the material from the neutron star to emit some electromagnetic counterpart that we can observe from our telescopes.”

    Once they received the classification, the group immediately got to work analyzing the information provided from the gravitational wave observatories and making plans to take data of their own with DECam as soon as possible. “We had to jump into action right away to try to do the observation,” says Marcelle Soares-Santos, an astrophysicist at Brandeis University who was at home when she received the first LIGO-Virgo message on her phone. “We managed to be on the sky in less than 24 hours.”

    According to the alert, the slice of sky that the signal could have originated from was tiny, providing astronomers with a clear target at which to point their instruments.

    “It was clear from the beginning that this event was special,” Soares-Santos says. “Several of us ended up staying up multiple nights because we were observing the same area of the sky multiple times.”

    Continuing the chase

    To identify optical counterparts of the source, DES-GW scientists look for transients: short-lived bursts of electromagnetic energy. Over the course of seven observing nights, DES-GW identified approximately 23 potential sources for the gravitational waves. Over the last few weeks, the group has been examining each of these to try to rule out the possibility that they are other celestial objects.

    One of the most common contaminants in these candidates are supernovae. Physicists can identify whether an object is a supernova by observing how long it takes to disappear. Unlike a black hole-neutron star merger, which would fade quickly, the aftermath of these stellar explosions usually remains in the sky for around a month or more.

    Finding the optical counterpart of the black hole-neutron star collision would be exciting for several reasons. First of all, this would be the first detection of such an event, so it could help reveal how such a process happens—whether the neutron star is ripped apart by a black hole or swallowed in one fell swoop. By observing this process, physicists could learn about the material that neutron stars are made of, which is the densest matter in the universe. These mergers may also help researchers better understand which elements are generated during this process.

    At this point, enough time has passed that it’s unlikely that DES-GW will identify the optical counterpart to the gravitational waves produced from this likely neutron star-black hole collision. Still, even without the detection, the data gathered at electromagnetic instruments can be helpful. For example, it suggests that instead of colliding, the neutron star may simply have been swallowed by the black hole instead, leaving no visible signs.

    More observations of neutron star-black hole mergers will be necessary to determine how, exactly, this process is happening. Scientists don’t yet know for sure when LIGO-Virgo will hear another gravitational wave coming from this type of event. But there are still several months to go during the current observing run, so physicists are anticipating another detection that will be worth pursuing.

    “This was the most exciting event this season so far,” Soares-Santos says. “But I wouldn’t bet it’s the last.”

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 9:24 am on March 1, 2019 Permalink | Reply
    Tags: , , , , , , Multi-messenger astrophysics,   

    From “Physics”: “Synopsis: How to Test a Space-Based Gravitational-Wave Detector” 

    Physics LogoAbout Physics

    Physics Logo 2

    From “Physics”

    February 28, 2019
    Christopher Crockett

    Researchers propose a device to verify the performance of the laser-based equipment that will fly on the Laser Interferometer Space Antenna.


    ESA/NASA eLISA space based, the future of gravitational wave research


    The gold-platinum alloy cubes, of central importance to the upcoming LISA mission, have already been built and tested in the proof-of-concept LISA Pathfinder mission

    The European Space Agency is moving ahead with plans to launch a gravitational-wave detector called “LISA” into space. LISA, which stands for Laser Interferometer Space Antenna, will listen for gravitational waves that are currently undetectable from ground-based facilities such as the Laser Interferometer Gravitational-Wave Observatory. Catching these subtle spacetime ripples will require instrumentation with phenomenally stringent precision. Now, researchers have developed a device to test a core piece of LISA’s laser-based technology and ensure that it meets the requisite performance requirements.

    1
    D. Penkert/Max Planck Institute for Gravitational Physics

    Max Planck Institute for Gravitational Physics


    The planned LISA detector consists of three spacecrafts flying in triangle formation. Incoming gravitational waves will change the 2.5 million kilometers between each spacecraft by a few trillionths of a meter. To track those changes, the spacecraft will look for phase shifts in the laser light they receive from their two companions, a feat requiring precise measuring instruments with exceptionally low noise and low distortion.

    To test the precision of LISA’s phase-shift-measuring hardware, Thomas Schwarze and colleagues at the Max Planck Institute for Gravitational Physics in Germany built and trialed a calibration device. Their device consists of three lasers whose beams interfere with each other in such a way that their phases—after being extracted by a prototype of LISA’s phase-measuring hardware—should cancel each other out. Any nonzero value reported reflects noise or distortion introduced by the phase-measuring hardware.

    Others have suggested using three-laser setups to test LISA’s detectors, but the team’s device introduces an order of magnitude less noise than other proposals. With further refinements to their setup—such as swapping out photodetectors for models with lower noise—the team envisions that they could reduce measurement noise further. Doing that, they say, could enable their setup to serve as a critical performance check for LISA’s hardware.

    This research is published in Physical Review Letters.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments (physics@aps.org).

     
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