DOCSLIB.ORG

Full White Paper

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

LIGO SCIENTIFIC COLLABORATION VIRGO COLLABORATION Document Type LIGO–T1400054 VIR-0176A-14 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics (2014-2015 edition) The LSC-Virgo Search Groups, the Data Analysis Software Working Group, the Detector Characterization Working Group and the Computing Committee WWW: http://www.ligo.org/ and http://www.virgo.infn.it Processed with LATEX on 2014/11/21 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics Contents 1 The LSC-Virgo White Paper on Data Analysis 4 1.1 Searches for Signals from Compact Binary Coalescences . .5 1.2 Searches for Generic Transients, or Bursts . .7 1.3 Searches for Continuous Wave Signals . .9 1.4 Searches for Stochastic Gravitational Wave Backgrounds . 11 1.5 Characterization of the Detectors and their Data . 13 1.6 Data Calibration . 15 1.7 Hardware Injections . 16 1.8 Computing and Software . 17 2 Previous Accomplishments (2013-2014) 19 2.1 Burst Working Group . 19 2.2 Compact Binary Coalescences Working Group . 19 2.3 Continuous Waves Group . 20 2.4 Stochastic Group . 21 2.5 Detector Characterization . 21 3 Search Plans for the Advanced Detector Era 23 3.1 All-Sky Burst Search . 24 3.2 Search For Binary Neutron Star Coalescences . 29 3.3 Search for Stellar-Mass Binary Black Hole Coalescences . 37 3.4 Search For Neutron Star – Black Hole Coalescences . 45 3.5 Search for GRB Sources of Transient Gravitational Waves . 57 3.6 Search for Intermediate Mass Black Hole Binary Coalescences . 64 3.7 All-sky Searches for Isolated Spinning Neutron Stars . 69 3.8 Targeted Searches for Gravitational Waves from Known Pulsars . 77 3.9 Search for an Isotropic Stochastic Gravitational Wave Background . 82 3.10 Directional Search for Persistent Gravitational Waves . 88 3.11 Directed Searches for Gravitational Waves from Isolated Neutron Stars . 94 3.12 Directed Searches for Scorpius X-1 and Other Known Binary Stars . 100 3.13 Search for transients from Cosmic Strings . 110 3.14 All-sky Searches for Spinning Neutron Stars in Binary Systems . 114 3.15 Search for Eccentric Binary Black Holes . 120 3.16 Search for Intermediate-mass-ratio Coalescences . 125 3.17 High-energy Neutrino Multimessenger Analysis . 131 3.18 Searches For Transient Gravitational Waves From Isolated Neutron Stars . 136 3.19 Gravitational-Waves from Galactic and Near-Extragalactic Core-Collapse Supernovae . 143 3.20 Search for transients in coincidence with Fast Radio Bursts . 149 3.21 Contributions of long transient gravitational waves to the stochastic background search . 152 4 Ongoing searches on Initial Detector Data and activities not ready for a Search Plan 156 4.1 Burst Working Group . 156 4.2 Compact Binary Coalescences Working Group . 166 4.3 Continuous Waves Group . 168 4.4 Stochastic Group . 194 2 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics 5 Characterization of the Detectors and Their Data 200 5.1 LSC Detector Characterization . 200 References 214 3 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics 1 The LSC-Virgo White Paper on Data Analysis Gravitational-wave searches and astrophysics in the LIGO Scientific Collaboration (LSC) and Virgo collab- oration are organized into four LSC-Virgo working groups: compact binary coalescences (CBC), generic transients (Burst), continuous waves (CW) and stochastic gravitational-wave background (SGWB). Each of these groups pursues distinct astrophysical sources of gravitational waves with different methods. Joint teams formed from the members of two or more working groups exist, where the science suggests over- lap between sources or methods. In addition to these astrophysics groups, the Detector Characterization group, which also collaborates with the detector commissioning teams, works to improve search sensitivity by identifying and mitigating instrumental noise sources that limit the sensitivity to astrophysical signals. The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics describes the goals, status, and plans of the data analysis teams in the LSC and Virgo, as well as plans and status of Detector Characteri- zation, calibration and development and maintenance of software tools and the management of software and computing resources. This document, which is revised and updated every year, is intended to facilitate the understanding of the science that we are pursuing, the prioritization of our objectives, the development plan and resource needs. The 2014-2015 version offers a significant re-structure from previous year, resulting from discussions in the LSC-Virgo Data Analysis Council, with four components: 1. Chapter 1 is the executive summary for this white paper, outlining for each search group a mission statement and a ranked list of priorities both in terms of scientific targets and tasks in preparation for Advanced LIGO and Advanced Virgo. 2. Chapter 2 lists papers and milestones from the period May 2013-May 2014. 3. Chapter 3 is a collection of search plans for Advanced LIGO and Advanced Virgo, with details on developments and resources. The plans can also be read as standalone documents and will be updated on a 6-month timescale. 4. Chapter 4 includes ongoing analysis on initial detector data or exploratory work that do not yet fit the search plan template. We refer to the Advanced Detector Era (ADE) as the epoch of Advanced LIGO and Advanced Virgo science data acquisition, currently scheduled to start in the second half of 2015. The schedule of science run is formulated by the LSC-Virgo Joint Running Plan Committee, which includes representatives from the laboratories, the commissioning teams and search groups, and the plans are formulated according to the schedule outlined in the document "Prospects for Localization of Gravitational Wave Transients by the Advanced LIGO and Advanced Virgo Observatories" (arXiv:1304.0670). −2 2 Estimated EGW = 10 M c Number % BNS Localized Run Burst Range (Mpc) BNS Range (Mpc) of BNS within Epoch Duration LIGO Virgo LIGO Virgo Detections 5 deg2 20 deg2 2015 3 months 40 – 60 – 40 – 80 – 0.0004 – 3 – – 2016–17 6 months 60 – 75 20 – 40 80 – 120 20 – 60 0.006 – 20 2 5 – 12 2017–18 9 months 75 – 90 40 – 50 120 – 170 60 – 85 0.04 – 100 1 – 2 10 – 12 2019+ (per year) 105 40 – 80 200 65 – 130 0.2 – 200 3 – 8 8 – 28 2022+ (India) (per year) 105 80 200 130 0.4 – 400 17 48 Table 1: Summary of a plausible observing schedule, expected sensitivities, and source localization with the advanced LIGO and Virgo detectors, which will be strongly dependent on the detectors’ commissioning progress. Extracted from arXiv:1304.0670 4 The LSC-Virgo White Paper on Gravitational Wave Searches and Astrophysics 1.1 Searches for Signals from Compact Binary Coalescences The inspiral and merger of a binary containing stellar-mass compact objects (i.e., neutron stars and black holes) generates gravitational waves which sweep upward in frequency and amplitude through the sensitive band of ground-based gravitational-wave detectors. The highly relativistic speeds and strongly- curved spacetimes of compact object mergers generate gravitational waves that will reveal the physics of strong-field gravity. The gravitational waves from mergers involving black holes will allow us to explore General Relativity and the nature of gravity. With densities of matter inaccessible to terrestrial experiments, mergers involving neutron stars hold the key to understanding the equation of state of nuclear matter. This is a crucial piece of fundamental physics missing from our understanding of the universe. Compact object mergers may also explain the origin and distribution of rare heavy elements and reveal the engine powering gamma-ray bursts. Measuring the masses and spins of a population of compact objects in the universe can help explain how stellar collapse forms neutron stars and black holes. At design sensitivity, Advanced LIGO will be able to detect binary neutron star (BNS) mergers to a maximum distance of 400 Mpc, neutron star–black hole (NSBH) binaries to 1 Gpc, and stellar-mass binary black holes (BBHs)∼ at distances over 2 Gpc. LIGO and Virgo conduct their∼ searches jointly giving us a three-detector network that can be used to localize sources on the sky. A wide variety of electromagnetic counterparts are expected to accompany the gravitational waves from compact object mergers, ranging from radio, through optical to x-rays and gamma-rays. The joint observation of a source by LIGO, Virgo, high- energy satellites, optical, and radio observatories will be a watershed event in astrophysics. The scientific program of the LSC/Virgo Compact Binary Coalescence (CBC) Group is designed to identify gravitational wave signals from compact binary sources in the detector data, measure the waveform parameters, and use detected signals study the nature of gravity and the astrophysics of nature’s most com- pact objects. Detection and parameter measurement of CBC signals is carried out by the joint LSC-Virgo CBC working group. The CBC group’s science program requires accurate modeling of gravitational wave sources to maximize detection rates, and to accurately measure parameters. The CBC group has an active collaboration with the theoretical astrophysics, source modeling and numerical relativity communities to address these challenges. The LSC charter states that the mission of the LSC is to detect gravitational waves, use them to explore the fundamental physics of gravity, and develop gravitational wave observations as a tool of astronomical discovery. We prioritize CBC tasks both in view of this mission statement and in terms of their chronological importance in the advanced detector era. Accordingly, highest priority is given to the ability to detect the most probable CBC sources with the LIGO and Virgo detectors, followed by science with the first detections (high priority), and finally the detection of sources which in the current astrophysical paradigm may have a low rate within the detectors’ volume reach, but whose discovery would nevertheless be of great astrophysical importance (priority).
Recommended publications
  • String Theory. Volume 1, Introduction to the Bosonic String

    String Theory. Volume 1, Introduction to the Bosonic String

    This page intentionally left blank String Theory, An Introduction to the Bosonic String The two volumes that comprise String Theory provide an up-to-date, comprehensive, and pedagogic introduction to string theory. Volume I, An Introduction to the Bosonic String, provides a thorough introduction to the bosonic string, based on the Polyakov path integral and conformal field theory. The first four chapters introduce the central ideas of string theory, the tools of conformal field theory and of the Polyakov path integral, and the covariant quantization of the string. The next three chapters treat string interactions: the general formalism, and detailed treatments of the tree-level and one loop amplitudes. Chapter eight covers toroidal compactification and many important aspects of string physics, such as T-duality and D-branes. Chapter nine treats higher-order amplitudes, including an analysis of the finiteness and unitarity, and various nonperturbative ideas. An appendix giving a short course on path integral methods is also included. Volume II, Superstring Theory and Beyond, begins with an introduction to supersym- metric string theories and goes on to a broad presentation of the important advances of recent years. The first three chapters introduce the type I, type II, and heterotic superstring theories and their interactions. The next two chapters present important recent discoveries about strongly coupled strings, beginning with a detailed treatment of D-branes and their dynamics, and covering string duality, M-theory, and black hole entropy. A following chapter collects many classic results in conformal field theory. The final four chapters are concerned with four-dimensional string theories, and have two goals: to show how some of the simplest string models connect with previous ideas for unifying the Standard Model; and to collect many important and beautiful general results on world-sheet and spacetime symmetries.
  • Stephen Hawking: 'There Are No Black Holes' Notion of an 'Event Horizon', from Which Nothing Can Escape, Is Incompatible with Quantum Theory, Physicist Claims

    Stephen Hawking: 'There Are No Black Holes' Notion of an 'Event Horizon', from Which Nothing Can Escape, Is Incompatible with Quantum Theory, Physicist Claims

    NATURE | NEWS Stephen Hawking: 'There are no black holes' Notion of an 'event horizon', from which nothing can escape, is incompatible with quantum theory, physicist claims. Zeeya Merali 24 January 2014 Artist's impression VICTOR HABBICK VISIONS/SPL/Getty The defining characteristic of a black hole may have to give, if the two pillars of modern physics — general relativity and quantum theory — are both correct. Most physicists foolhardy enough to write a paper claiming that “there are no black holes” — at least not in the sense we usually imagine — would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape. In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, “There is no escape from which only temporarily holds matter and energy prisoner before eventually a black hole in classical releasing them, albeit in a more garbled form. theory, but quantum theory enables energy “There is no escape from a black hole in classical theory,” Hawking told Nature. Peter van den Berg/Photoshot and information to Quantum theory, however, “enables energy and information to escape from a escape.” black hole”. A full explanation of the process, the physicist admits, would require a theory that successfully merges gravity with the other fundamental forces of nature.
  • Philippa Hartley Title Abstract

    Philippa Hartley Title Abstract

    Philippa Hartley Title Cosmic telescopes: witnessing the emission mechanism of radio quiet quasars Abstract The quasar model has reached relative maturity: we know that light is emitted at great power across the electromagnetic spectrum from the active nuclei of distant galaxies, where violent accretion processes release huge amounts of energy from gravitational stores. We observe that, in some quasars, matter falling onto the central black hole is funnneled into dramatic jets, emitting radio light across galactic distances. Over cosmic history the quasar population peaked in unison with star formation activity, leading us to suspect the role of quasars in the quenching of star-formation. Missing from the picture, however, is a full understanding of how such feedback processes manifest in the vast majority of quasars: those objects with very little radio emission. In these 'radio-quiet' quasars, jets appear to be absent, and it is possible that the faint radio signal that we do detect is the result either of smaller-scale AGN activity, of continued star formation, or of both. Only by undestanding the source of this very faint emission can we fully understand the quasar stage of galaxy evolution. This talk presents findings using strong gravitational lenses as 'cosmic telescopes' that magnify distant source structure, allowing us to resolve these intriguing objects to the sub-parsec scale. Philippa Hartley SKA Organisation, Jodrell Bank Observatory, Cheshire, SK11 9FT, UK +44 (0)161 306 9600 · [email protected] RESEARCH INTERESTS
  • Anomalies, Dualities, and Topology of D = 6 N = 1 Superstring Vacua

    Anomalies, Dualities, and Topology of D = 6 N = 1 Superstring Vacua

    RU-96-16 NSF-ITP-96-21 CALT-68-2057 IASSNS-HEP-96/53 hep-th/9605184 Anomalies, Dualities, and Topology of D =6 N =1 Superstring Vacua Micha Berkooz,1 Robert G. Leigh,1 Joseph Polchinski,2 John H. Schwarz,3 Nathan Seiberg,1 and Edward Witten4 1Department of Physics, Rutgers University, Piscataway, NJ 08855-0849 2Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030 3California Institute of Technology, Pasadena, CA 91125 4Institute for Advanced Study, Princeton, NJ 08540 Abstract We consider various aspects of compactifications of the Type I/heterotic Spin(32)/Z2 theory on K3. One family of such compactifications in- cludes the standard embedding of the spin connection in the gauge group, and is on the same moduli space as the compactification of arXiv:hep-th/9605184v1 25 May 1996 the heterotic E8 × E8 theory on K3 with instanton numbers (8,16). Another class, which includes an orbifold of the Type I theory re- cently constructed by Gimon and Polchinski and whose field theory limit involves some topological novelties, is on the moduli space of the heterotic E8 × E8 theory on K3 with instanton numbers (12,12). These connections between Spin(32)/Z2 and E8 × E8 models can be demonstrated by T duality, and permit a better understanding of non- perturbative gauge fields in the (12,12) model. In the transformation between Spin(32)/Z2 and E8 × E8 models, the strong/weak coupling duality of the (12,12) E8 × E8 model is mapped to T duality in the Type I theory. The gauge and gravitational anomalies in the Type I theory are canceled by an extension of the Green-Schwarz mechanism.
  • N O T I C E This Document Has Been Reproduced From

    N O T I C E This Document Has Been Reproduced From

    N O T I C E THIS DOCUMENT HAS BEEN REPRODUCED FROM MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE P993-198422 International Collogium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas (4th) Held at the National institute of Standards and Technology Gaithersburg, Maryland on September 14-17, 1992 (U.S.) National inst. of Standards and Technology (PL) Gaithersburg, MD Apr 93 US. DEPARTMENT OF COMMERCE Ndioul Techcical IMermeNON Service B•11G 2-10i1A2 2 MIST-1 /4 U.S. VZPARTMENT OF COMMERCE (REV. NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY M GONTSOLw1N^BENN O4" COMM 4M /. MANUSCRIPT REVIEW AND APPROVAL "KIST/ p-850 ^' THIS NSTRUCTWNS: ATTACH ORIGINAL OF FORM TO ONE (1) COPY OF MANUSCIIN IT AND SEINE TO: PUBLICATIOM OATS NUMBER PRINTED PAGES April 1993 199 HE SECRETAIIY, APPROPRIATE EDITO RIAL REVIEW BOARD. ITLE AND SUBTITLE (CITE NN PULL) 4rh International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas -- POSTER PAPERS :ONTIEACT OR GRANT NUMBER TYPE OF REPORT AND/OR PERIOD COMM UTHOR(S) (LAST %,TAME, POST NNITIAL, SECOND INITIAL) PERFORM" ORGANIZATION (CHECK (IQ ONE SOX) EDITORS XXX MIST/GAITHERSBUIIG Sugar, Jack and Leckrone, B:;vid INST/BODUM JILA BOIRDE11 "ORATORY AND DIVISION NAMES (FIRST MOST AUTHOR ONLY) Physics Laboratory/Atomic Physics Division 'PONSORING ORGANIZATION NAME AND COMPLETE ADDRESS TREET, CITY. STATE. ZNh ^y((S/ ,T AiL7A - -ASO IECOMMENDsO FOR MIST PUBLICATION JOVIAMAL OF RESEMICM (MIST JRES) CIONOGRAPK (MIST MN) LETTER CIRCULAR J. PHYS. A CHEM.
  • Eternal Inflation and Its Implications

    Eternal Inflation and Its Implications

    IOP PUBLISHING JOURNAL OF PHYSICS A: MATHEMATICAL AND THEORETICAL J. Phys. A: Math. Theor. 40 (2007) 6811–6826 doi:10.1088/1751-8113/40/25/S25 Eternal inflation and its implications Alan H Guth Center for Theoretical Physics, Laboratory for Nuclear Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA E-mail: [email protected] Received 8 February 2006 Published 6 June 2007 Online at stacks.iop.org/JPhysA/40/6811 Abstract Isummarizetheargumentsthatstronglysuggestthatouruniverseisthe product of inflation. The mechanisms that lead to eternal inflation in both new and chaotic models are described. Although the infinity of pocket universes produced by eternal inflation are unobservable, it is argued that eternal inflation has real consequences in terms of the way that predictions are extracted from theoretical models. The ambiguities in defining probabilities in eternally inflating spacetimes are reviewed, with emphasis on the youngness paradox that results from a synchronous gauge regularization technique. Although inflation is generically eternal into the future, it is not eternal into the past: it can be proven under reasonable assumptions that the inflating region must be incomplete in past directions, so some physics other than inflation is needed to describe the past boundary of the inflating region. PACS numbers: 98.80.cQ, 98.80.Bp, 98.80.Es 1. Introduction: the successes of inflation Since the proposal of the inflationary model some 25 years ago [1–4], inflation has been remarkably successful in explaining many important qualitative and quantitative properties of the universe. In this paper, I will summarize the key successes, and then discuss a number of issues associated with the eternal nature of inflation.
  • 2000 Annual Report

    2000 Annual Report

    2001 ANNUAL REPORT ALFRED P. SLOAN FOUNDATION 1 CONTENTS 2001 Grants and Activities Science and Technology 5 Fellowships 5 Sloan Research Fellowships 5 Direct Support of Research 9 Neuroscience 9 Computational Molecular Biology 9 Limits to Knowledge 10 Marine Science 11 Other Science and Science Policy 15 History of Science and Technology 16 Standard of Living and Economic Performance 17 Industries 17 Industry Centers 17 Human Resources/Jobs/Income 21 Globalization 21 Business Organizations 22 Economics Research and Other Work 24 Nonprofit Sectors 26 Universities 26 Assessment of Government Performance 26 Work, Workforce and Working Families 30 Centers on Working Families 30 Workplace Structure and Opportunity 31 Working Families and Everyday Life 34 Education and Careers in Science and Technology 36 Scientific and Technical Careers 36 Anytime, Anyplace Learning 36 Professional Master’s Degrees 42 Information about Careers 47 Entry and Retention 48 Science and Engineering Education 48 Education for Minorities and Women 49 Minorities 49 Women 53 Public Understanding of Science and Technology 55 Books 55 Sloan Technology Book Series 57 Radio 58 2 Public Television 59 Commercial Television and Films 60 Theater 61 General 63 Selected National Issues and The Civic Program 64 Selected National Issues 64 September 11 64 Bioterrorism 66 Energy 68 Federal Statistics 69 Public Policy Research 69 The Civic Program 71 Additional Grants 73 2001 Financial Report Financial Review 75 Auditors’ Report 76 Balance Sheets 77 Statements of Activities 78 Statements of Cash Flows 79 Notes to Financial Statements 80 Schedules of Management and Investment Expenses 83 3 2001 GRANTS AND ACTIVITIES 4 SCIENCE AND TECHNOLOGY FELLOWSHIPS Sloan Research Fellowships $4,160,000 The Sloan Research Fellowship Program aims to stimulate fundamental research by young scholars with outstanding promise to contribute significantly to the advancement of knowledge.
  • Analytic Approaches to the Study of Small Scale Structure on Cosmic String Networks

    Analytic Approaches to the Study of Small Scale Structure on Cosmic String Networks

    UNIVERSITY of CALIFORNIA Santa Barbara Analytic Approaches to the Study of Small Scale Structure on Cosmic String Networks A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Physics by Jorge V. Rocha arXiv:0812.4020v1 [gr-qc] 20 Dec 2008 Committee in charge: Professor Joseph Polchinski, Chair Professor Tommaso Treu Professor Donald Marolf September 2008 The dissertation of Jorge V. Rocha is approved: Professor Tommaso Treu Professor Donald Marolf Professor Joseph Polchinski, Chair August 2008 Analytic Approaches to the Study of Small Scale Structure on Cosmic String Networks Copyright 2008 by Jorge V. Rocha iii To my parents, Carlos and Isabel iv Acknowledgements In writing these lines I think of the people without whom I would not be writing these lines. To the person who taught me the inner workings of science, Joe Polchinski, I am deeply grateful. Thank you, Joe, for sharing your knowledge and insight with me, for showing me the way whenever I got off track and for your powerful educated guesses. Over these years I have also had the opportunity of collaborating with Florian Dubath. For this and for his enthusiasm I am thankful. I was fortunate enough to have Don Marolf and Tommaso Treu as committee members. I learned much about physics from Don, and always with a good feeling about it. I am grateful for your constructive criticism as well. From Tommaso I appreciate him always keeping an open door for me and also showing so much interest. I thank both of you for all that.
  • Prospects for Weak Lensing Studies with New Radio Telescopes

    Prospects for Weak Lensing Studies with New Radio Telescopes

    PROSPECTS FOR WEAK LENSING STUDIES WITH NEW RADIO TELESCOPES MICHAEL L. BROWN Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL I consider the prospects for performing weak lensing studies with the new generation of radio telescopes that are coming online now and in the future. I include a description of a proposed technique to use polarization observations in radio weak lensing analyses which could prove extremely useful for removing a contaminating signal from intrinsic alignments. Ultimately, the Square Kilometre Array promises to be an exceptional instrument for performing weak lensing studies due to the high resolution, large area surveys which it will perform. In the nearer term, the e-MERLIN instrument in the UK offers the high sensitivity and sub-arcsec resolution required to prove weak lensing techniques in the radio band. I describe the Su- perCLASS survey – a recently accepted e-MERLIN legacy programme which will perform a pioneering radio weak lensing analysis of a supercluster of galaxies. 1 Weak lensing in the radio band Weak gravitational lensing is the coherent distortion in the images of faint background galaxies due to gravitational light deflection caused by intervening (dark) matter distributions. On the very largest scales, the effect traces the large scale structure of the Universe and is known as cosmic shear. The vast majority of weak lensing surveys to date have been conducted in the optical bands since large numbers of background galaxies are required in order to measure the small (∼ a few %) distortions. However, a new generation of powerful radio facilities is now imminent which makes weak lensing in the radio band a viable alternative.
  • Arxiv:1411.0399V2 [Astro-Ph.HE] 16 Mar 2016 to the X-Ray Luminosity Indicate That PSR J1745-2900 Is Not a Rotation-Powered Pulsar but a Magnetar

    Arxiv:1411.0399V2 [Astro-Ph.HE] 16 Mar 2016 to the X-Ray Luminosity Indicate That PSR J1745-2900 Is Not a Rotation-Powered Pulsar but a Magnetar

    Draft version March 17, 2016 Preprint typeset using LATEX style emulateapj v. 5/2/11 THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A* Geoffrey C. Bower1, Adam Deller2, Paul Demorest3, Andreas Brunthaler4, Heino Falcke5,2,4, Monika Moscibrodzka5, Ryan M. O'Leary6, Ralph P. Eatough4, Michael Kramer4,7, K.J. Lee4, Laura Spitler4, Gregory Desvignes4, Anthony P. Rushton8,9, Sheperd Doeleman10,11, Mark J. Reid11 Draft version March 17, 2016 ABSTRACT We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic Center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 ± 11 km s−1 at position angle 22 ± 2 deg East of North at a projected separation of 0.097 pc from Sgr A*. Given the unknown radial velocity, this transverse velocity measurement does not conclusively prove that the pulsar is bound to Sgr A*; however, the probability of chance alignment is very small. We do show that the velocity and position is consistent with a bound orbit originating in < −1 the clockwise disk of massive stars orbiting Sgr A* and a natal velocity kick of ∼ 500 km s . An origin among the isotropic stellar cluster is possible but less probable. If the pulsar remains radio-bright, multi-year astrometry of PSR J1745-2900 can detect its acceleration and determine the full three- dimensional orbit. We also demonstrate that PSR J1745-2900 exhibits the same angular broadening as Sgr A* over a wavelength range of 3.6 cm to 0.7 cm, further confirming that the two sources share the same interstellar scattering properties.
  • Rotation Velocities of Red and Blue Field Horizontal-Branch Stars

    Rotation Velocities of Red and Blue Field Horizontal-Branch Stars

    Rotation Velocities of Red and Blue Field Horizontal-Branch Stars Bradford B. Behr McDonald Observatory 1 University Station, C1400 Austin TX 78712–0259 [email protected] ABSTRACT We present measurements of the projected stellar rotation velocities (v sin i) of a sample of 45 candidate field horizontal-branch (HB) stars spanning a wide range of effective temperature, from red HB stars with Teff ≃ 5000K to blue HB stars with Teff of 17000K. Among the cooler blue HB stars (Teff = 7500– 11500 K), we confirm prior studies showing that although a majority of stars rotate at v sin i < 15 km s−1, there exists a subset of “fast rotators” with v sin i as high as 30–35kms−1. All but one of the red HB stars in our sample have v sin i < 10 km s−1, and no analogous rotation bimodality is evident. We also identify a narrow-lined hot star (Teff ≃ 16000 K) with enhanced photospheric metal abundances and helium depletion, similar to the abundance patterns found among hot BHB stars in globular clusters, and four other stars that may also belong in this category. We discuss details of the spectral line fitting procedure that we use to deduce v sin i, and explore how measurements of field HB star rotation may shed light on the issue of HB star rotation in globular clusters. arXiv:astro-ph/0307232v1 11 Jul 2003 Subject headings: stars: horizontal-branch, stars: rotation, stars: abundances 1. Introduction and motivation The horizontal branch (HB) stars found in globular clusters exhibit a variety of photo- metric and spectroscopic characteristics which are not well explained by canonical models of stellar evolution.
  • High Neutron Star Birth Velocities and Gravitational Radiation During Supernova Explosions

    High Neutron Star Birth Velocities and Gravitational Radiation During Supernova Explosions

    A&A manuscript no. (will be inserted by hand later) ASTRONOMY AND Your thesaurus codes are: ASTROPHYSICS 01 (02.07.2; 08.14.1; 08.19.4) 19.5.2018 High Neutron Star Birth Velocities and Gravitational Radiation during Supernova Explosions S.N.Nazin1 and K.A. Postnov1,2 1 Sternberg Astronomical Institute, Moscow University, 119899 Moscow, Russia 2 Faculty of Physics, Moscow University, 117234 Moscow, Russia Received ... 1996, accepted ..., 1996 Abstract. Assuming the observed pulsar velocities to precessing binary pulsar orbit in PSR J0045-7319 in the originate during asymmetric collapse of stellar cores, we SMC (Kaspi et al. 1996). The collapse asymmetry result- compute the amplitude of gravitational waves emitted ing in the kick velocity of a neutron star at birth may during type II and Ib supernova explosions and their de- be due to different reasons. For example, recent calcula- tection rate from within a distance of 30 Mpc. At the tions of Burrows & Hayes (1996) has shown the ability rms-level of advanced laser interferometers h 10−22 at of neutrino anisotropic emission to produce kick velocities frequencies 300 1000 Hz the expected rate is about≈ 1 per of 400-500 km/s, as observed (see also Imshennik 1992; year. − Bisnovatyi-Kogan 1993). One of the consequences of Lyne and Lorimer’s result Key words: Gravitational waves — Stars: neutron — was a recognition that the kick velocity imparted to a neu- Supernovae: general tron star at birth has a power-law asymptotic form at high velocities (Lipunov, Postnov & Prokhorov 1996a,b). Using direct Monte-Carlo calculations of binary star evolution (the so-called “Scenario Machine”), they found that the Supernova explosions are among the most violent Lyne-Lorimer pulsar transverse velocities are best repro- events known in nature.