17 research outputs found
Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA
We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star-black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of 105,106,107 Mpc3 for binary neutron star, neutron star-black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of 1+12−1(10+52−10) for binary neutron star mergers, of 0+19−0(1+91−1) for neutron star-black hole mergers, and 17+22−11(79+89−44) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers
A guide to LIGO-Virgo detector noise and extraction of transient gravitational-wave signals
The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellar-mass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitational-wave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data and methods used in the analyses. In this paper, we provide an overview of the detector noise properties and the data analysis techniques used to detect gravitational-wave signals and infer the source properties. We describe some of the checks that are performed to validate the analyses and results from the observations of gravitational-wave events. We also address concerns that have been raised about various properties of LIGO-Virgo detector noise and the correctness of our analyses as applied to the resulting data.The authors gratefully acknowledge the support of the United States National Science
Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced
LIGO as well as the Science and Technology Facilities Council (STFC) of the United
Kingdom, the Max-Planck-Society (MPS), and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and construction and operation of the GEO600
detector. Additional support for Advanced LIGO was provided by the Australian Research
Council. The authors gratefully acknowledge the Italian Istituto Nazionale di Fisica Nucleare
(INFN), the French Centre National de la Recherche Scientifique (CNRS) and the Foundation
for Fundamental Research on Matter supported by the Netherlands Organisation for Scientific
Research, for the construction and operation of the Virgo detector and the creation and support of the EGO consortium. The authors also gratefully acknowledge research support from
these agencies as well as by the Council of Scientific and Industrial Research of India, the
Department of Science and Technology, India, the Science & Engineering Research Board
(SERB), India, the Ministry of Human Resource Development, India, the Spanish Agencia
Estatal de Investigación, the Vicepresidència i Conselleria d’Innovació, Recerca i Turisme
and the Conselleria d’Educació i Universitat del Govern de les Illes Balears, the Conselleria
d’Educació, Investigació, Cultura i Esport de la Generalitat Valenciana, the National Science
Centre of Poland, the Swiss National Science Foundation (SNSF), the Russian Foundation for
Basic Research, the Russian Science Foundation, the European Commission, the European
Regional Development Funds (ERDF), the Royal Society, the Scottish Funding Council, the
Scottish Universities Physics Alliance, the Hungarian Scientific Research Fund (OTKA),
the Lyon Institute of Origins (LIO), the Paris Île-de-France Region, the National Research,
Development and Innovation Office Hungary (NKFIH), the National Research Foundation
of Korea, Industry Canada and the Province of Ontario through the Ministry of Economic
Development and Innovation, the Natural Science and Engineering Research Council Canada,
the Canadian Institute for Advanced Research, the Brazilian Ministry of Science, Technology,
Innovations, and Communications, the International Center for Theoretical Physics South
American Institute for Fundamental Research (ICTP-SAIFR), the Research Grants Council
of Hong Kong, the National Natural Science Foundation of China (NSFC), the Leverhulme
Trust, the Research Corporation, the Ministry of Science and Technology (MOST), Taiwan
and the Kavli Foundation. The authors gratefully acknowledge the support of the NSF, STFC,
INFN and CNRS for provision of computational resources. This article has been assigned the
document number LIGO-P1900004
Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network
Gravitational-wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar-mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational-wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event is detected in this search. Consequently, we place upper limits on the merger rate density for a family of intermediate mass black hole binaries. In particular, we choose sources with total masses M ¼ m1 þ m2 ∈ ½120; 800 M⊙ and mass ratios q ¼ m2=m1 ∈ ½0.1; 1.0. For the first time, this calculation is done using numerical relativity waveforms (which include higher modes) as models of the real emitted signal. We place a most stringent upper limit of 0.20 Gpc−3 yr−1 (in comoving units at the 90% confidence level) for equal-mass binaries with individual masses m1;2 ¼ 100 M⊙ and dimensionless spins χ1;2 ¼ 0.8 aligned with the orbital angular momentum of the binary. This improves by a factor of ∼5 that reported after Advanced LIGO’s first observing run.The authors gratefully acknowledge the support of the United States National Science Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced LIGO as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the MaxPlanck-Society (MPS), and the State of Niedersachsen/ Germany for support of the construction of Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. The authors gratefully acknowledge the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS), and the Foundation for Fundamental Research on Matter supported by the Netherlands Organisation for Scientific Research, for the construction and operation of the Virgo detector and the creation and support of the EGO consortium. The authors also gratefully acknowledge research support from these agencies as well as by the Council of Scientific and Industrial Research of India, the Department of Science and Technology, India, the Science & Engineering Research Board, India, the Ministry of Human Resource Development, India, the Spanish Agencia Estatal de Investigación, the Vicepresid`encia i Conselleria d’Innovació, Recerca i Turisme and the Conselleria d’Educació i Universitat del Govern de les Illes Balears, the Conselleria d’Educació, Investigació, Cultura i Esport de la Generalitat Valenciana, the National Science Centre of Poland, the Swiss National Science Foundation, the Russian Foundation for Basic Research, the Russian Science Foundation, the European Commission, the European Regional Development Funds, the Royal Society, the Scottish Funding Council, the Scottish Universities Physics Alliance, the Hungarian Scientific Research Fund, the Lyon Institute of Origins, the Paris Île-de-France Region, the National Research, Development and Innovation Office Hungary, the National Research Foundation of Korea, Industry Canada and the Province of Ontario through the Ministry of Economic Development and Innovation, the Natural Science and Engineering Research Council Canada, the Canadian Institute for Advanced Research, the Brazilian Ministry of Science, Technology, Innovations, and Communications, the International Center for Theoretical Physics South American Institute for Fundamental Research, the Research Grants Council of Hong Kong, the National Natural Science Foundation of China, the Leverhulme Trust, the Research Corporation, the Ministry of Science and Technology, Taiwan, and the Kavli Foundation
Search for Gravitational-wave Signals Associated with Gamma-Ray Bursts during the Second Observing Run of Advanced LIGO and Advanced Virgo
We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of <9.38 10-6 (modeled) and 3.1 10-4 (unmodeled). We do not find any significant evidence for gravitational-wave signals associated with the other gamma-ray bursts analyzed, and therefore we report lower bounds on the distance to each of these, assuming various source types and signal morphologies. Using our final modeled search results, short gamma-ray burst observations, and assuming binary neutron star progenitors, we place bounds on the rate of short gamma-ray bursts as a function of redshift for z ≤ 1. We estimate 0.07-1.80 joint detections with Fermi-GBM per year for the 2019-20 LIGO-Virgo observing run and 0.15-3.90 per year when current gravitational-wave detectors are operating at their design sensitivities
Optically targeted search for gravitational waves emitted by core-collapse supernovae during the first and second observing runs of advanced LIGO and advanced Virgo
We present the results from a search for gravitational-wave transients associated with core-collapse supernovae observed within a source distance of approximately 20 Mpc during the first and second observing runs of Advanced LIGO and Advanced Virgo. No significant gravitational-wave candidate was detected. We report the detection efficiencies as a function of the distance for waveforms derived from multidimensional numerical simulations and phenomenological extreme emission models. The sources with neutrino-driven explosions are detectable at the distances approaching 5 kpc, and for magnetorotationally driven explosions the distances are up to 54 kpc. However, waveforms for extreme emission models are detectable up to 28 Mpc. For the first time, the gravitational-wave data enabled us to exclude part of the parameter spaces of two extreme emission models with confidence up to 83%, limited by coincident data coverage. Besides, using ad hoc harmonic signals windowed with Gaussian envelopes, we constrained the gravitational-wave energy emitted during core collapse at the levels of 4.27×10⁻⁴ M⊙c2 and 1.28×10⁻¹ M⊙c² for emissions at 235 and 1304 Hz, respectively. These constraints are 2 orders of magnitude more stringent than previously derived in the corresponding analysis using initial LIGO, initial Virgo, and GEO 600 data.The authors gratefully acknowledge the support of the
United States National Science Foundation (NSF) for the
construction and operation of the LIGO Laboratory and
Advanced LIGO as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the
Max-Planck-Society, and the State of Niedersachsen/
Germany for support of the construction of Advanced
LIGO and construction and operation of the GEO600
detector. Additional support for Advanced LIGO was
provided by the Australian Research Council. The authors
gratefully acknowledge the Italian Istituto Nazionale di
Fisica Nucleare (INFN), the French Centre National de la
Recherche Scientifique (CNRS), and the Foundation for
Fundamental Research on Matter supported by the
Netherlands Organisation for Scientific Research for
the construction and operation of the Virgo detector and
the creation and support of the European Gravitational
Observatory consortium. The authors also gratefully
acknowledge research support from these agencies as well
as by the Council of Scientific and Industrial Research of
India; the Department of Science and Technology, India;
the Science & Engineering Research Board, India; the
Ministry of Human Resource Development, India; the
Spanish Agencia Estatal de Investigación; the
Vicepresid`encia i Conselleria d’Innovació; Recerca i
Turisme and the Conselleria d’Educació i Universitat del
Govern de les Illes Balears; the Conselleria d’Educació,
Investigació, Cultura i Esport de la Generalitat Valenciana;
the National Science Centre of Poland; the Swiss National
Science Foundation; the Russian Foundation for Basic
Research; the Russian Science Foundation; the European
Commission; the European Regional Development Funds;
the Royal Society; the Scottish Funding Council; the
Scottish Universities Physics Alliance; the Hungarian
Scientific Research Fund; the Lyon Institute of Origins;
the Paris Île-de-France Region; the National Research,
Development and Innovation Office Hungary; the National
Research Foundation of Korea; Industry Canada and the
Province of Ontario through the Ministry of Economic
Development and Innovation; the Natural Science and Engineering Research Council Canada; the Canadian
Institute for Advanced Research; the Brazilian Ministry
of Science, Technology, Innovations, and
Communications; the International Center for Theoretical
Physics South American Institute for Fundamental
Research; the Research Grants Council of Hong Kong;
the National Natural Science Foundation of China; the
Leverhulme Trust; the Research Corporation; the Ministry
of Science and Technology, Taiwan; and the Kavli
Foundation. The authors gratefully acknowledge the support of the NSF, STFC, INFN and CNRS for provision of
computational resources. Research by D. J. S. is supported
by NSF Grants No. AST-1821987, No. AST-1821967,
No. AST-1813708, and No. AST-1813466. We thank the
Las Cumbres Observatory and its staff for its continuing
support of the ASAS-SN project. ASAS-SN is supported
by the Gordon and Betty Moore Foundation through Grant
No. GBMF5490 to the Ohio State University and NSF
Grant No. AST-1515927. Development of ASAS-SN has
been supported by NSF Grant No. AST-0908816, the Mt.
Cuba Astronomical Foundation, the Center for Cosmology
and AstroParticle Physics at the Ohio State University, the
Chinese Academy of Sciences South America Center for
Astronomy, the Villum Foundation, and George Skestos.
K. Z. S. and C. S. K. are supported by NSF Grants
No. AST-1515876, No. AST-1515927, and No. AST1814440. Support for J. L. P. is provided in part by
FONDECYT through Grant No. 1191038 and by the
Ministry of Economy, Development, and Tourism’s
Millennium Science Initiative through Grant
No. IC120009, awarded to The Millennium Institute of
Astrophysics, MAS. Research by S. V. is supported by NSF
Grant No. AST-1813176. We are thankful to the National
Science Foundation for support under Grant No. PHY
1806165. This document has been assigned LIGO
Laboratory document number LIGO-P1700177
Model comparison from LIGO-Virgo data on GW170817's binary components and consequences for the merger remnant
GW170817 is the very first observation of gravitational waves originating from the coalescence of two compact objects in the mass range of neutron stars, accompanied by electromagnetic counterparts, and offers an opportunity to directly probe the internal structure of neutron stars. We perform Bayesian model selection on a wide range of theoretical predictions for the neutron star equation of state. For the binary neutron star hypothesis, we find that we cannot rule out the majority of theoretical models considered. In addition, the gravitational-wave data alone does not rule out the possibility that one or both objects were low-mass black holes. We discuss the possible outcomes in the case of a binary neutron star merger, finding that all scenarios from prompt collapse to long-lived or even stable remnants are possible. For long-lived remnants, we place an upper limit of 1.9 kHz on the rotation rate. If a black hole was formed any time after merger and the coalescing stars were slowly rotating, then the maximum baryonic mass of non-rotating neutron stars is at most , and three equations of state considered here can be ruled out. We obtain a tighter limit of for the case that the merger results in a hypermassive neutron star
Tests of General Relativity with GW170817
The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary
neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for
the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this
Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian
coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are
obtained; in combination with information from the observed electromagnetic counterpart we can also
constrain effects due to large extra dimensions. Finally, the polarization content of the gravitational wave
signal is studied. The results of all tests performed here show good agreement with GR.The authors gratefully acknowledge the support of the
United States National Science Foundation (NSF) for
the construction and operation of the LIGO Laboratory
and Advanced LIGO as well as the Science and Technology
Facilities Council (STFC) of the United Kingdom,
the Max-Planck-Society (MPS), and the State of
Niedersachsen/Germany for support of the construction
of Advanced LIGO and construction and operation of the
GEO600 detector. Additional support for Advanced LIGO
was provided by the Australian Research Council
GW170817: Measurements of Neutron Star Radii and Equation of State
On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitational-wave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimal-assumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were neutron stars that are described by the same equation of state and have spins within the range observed in Galactic binary neutron stars. Our analysis employs two methods: the use of equation-of-state-insensitive relations between various macroscopic properties of the neutron stars and the use of an efficient parametrization of the defining function p(rho) of the equation of state itself. From the LIGO and Virgo data alone and the first method, we measure the two neutron star radii as R-1 = 10.8(-1.7)(+2.0) km for the heavier star and R-2 = 10.7(-1.5)(+2.1) km for the lighter star at the 90% credible level. If we additionally require that the equation of state supports neutron stars with masses larger than 1.97 M-circle dot as required from electromagnetic observations and employ the equation-of-state parametrization, we further constrain R-1 = 11.9(-1.4)(+1.4) km and R-2 = 11.9(-1.4)(+1.4) km at the 90% credible level. Finally, we obtain constraints on p(rho) at supranuclear densities, with pressure at twice nuclear saturation density measured at 3.5(-1.7)(+2.7) x 10(34) dyn cm(-2) at the 90% level.The authors gratefully acknowledge the support of the
U.S. National Science Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced
LIGO as well as the Science and Technology Facilities
Council (STFC) of the United Kingdom, the Max-PlanckSociety (MPS), and the State of Niedersachsen/Germany
for support of the construction of Advanced LIGO and
construction and operation of the GEO600 detector.
Additional support for Advanced LIGO was provided by
the Australian Research Council. The authors gratefully
acknowledge the Italian Istituto Nazionale di Fisica
Nucleare (INFN), the French Centre National de la
Recherche Scientifique (CNRS) and the Foundation for
Fundamental Research on Matter supported by the
Netherlands Organisation for Scientific Research, for
the construction and operation of the Virgo detector and
the creation and support of the EGO consortium. The
authors also gratefully acknowledge research support
from these agencies as well as by the Council of
Scientific and Industrial Research of India, the
Department of Science and Technology, India, the
Science & Engineering Research Board (SERB), India,
the Ministry of Human Resource Development, India, the
Spanish Agencia Estatal de Investigación, the Vicepresid`encia i Conselleria d’Innovació, Recerca i
Turisme and the Conselleria d’Educació i Universitat del
Govern de les Illes Balears, the Conselleria d’Educació,
Investigació, Cultura i Esport de la Generalitat Valenciana,
the National Science Centre of Poland, the Swiss National
Science Foundation (SNSF), the Russian Foundation for
Basic Research, the Russian Science Foundation, the
European Commission, the European Regional
Development Funds (ERDF), the Royal Society, the
Scottish Funding Council, the Scottish Universities
Physics Alliance, the Hungarian Scientific Research
Fund (OTKA), the Lyon Institute of Origins (LIO), the
Paris Île-de-France Region, the National Research,
Development and Innovation Office Hungary (NKFI),
the National Research Foundation of Korea, Industry
Canada and the Province of Ontario through the
Ministry of Economic Development and Innovation, the
Natural Science and Engineering Research Council
Canada, the Canadian Institute for Advanced Research,
the Brazilian Ministry of Science, Technology, Innovations,
and Communications, the International Center for
Theoretical Physics South American Institute for
Fundamental Research (ICTP-SAIFR), the Research
Grants Council of Hong Kong, the National Natural
Science Foundation of China (NSFC), the Leverhulme
Trust, the Research Corporation, the Ministry of Science
and Technology (MOST), Taiwan and the Kavli
Foundation. The authors gratefully acknowledge the support of the NSF, STFC, MPS, INFN, CNRS and the State of
Niedersachsen/Germany for provision of computational
resources
Multi-messenger Observations of a Binary Neutron Star Merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 {{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}⊙ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.The AST3 project is supported by the National Basic Research Program (973 Program) of China (Grant Nos. 2013CB834901, 2013CB834900, 2013CB834903), and the Chinese Polar Environment Comprehensive Investigation & Assessment Program (grant No. CHINARE2016-02-03-05). The construction of the AST3 telescopes has received fundings from Tsinghua University, Nanjing University, Beijing Normal University, University of New South Wales, and Texas A&M University, the Australian Antarctic Division, and the National Collaborative Research Infrastructure Strategy (NCRIS) of Australia. It has also received funding from Chinese Academy of Sciences through the Center for Astronomical Mega-Science and National Astronomical Observatory of China (NAOC).The collaboration between LIGO/Virgo and EVN/e-MERLIN is part of a project that has received funding from the European Unions Horizon 2020 research and innovation programme under grant agreement No. 653477.B.C., V.C., A.G., and W.S.P. gratefully acknowledge NASA funding through contract NNM13AA43C. M.S.B., R.H., P.J., C.A.M., S.P., R.D.P., M.S., and P.V. gratefully acknowledge NASA funding from cooperative agreement NNM11AA01A. E.B. is supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASA. D.K., C.A.W.H., C.M. H., and J.R. gratefully acknowledge NASA funding through the Fermi-GBM project. Support for the German contribution to GBM was provided by the Bundesministerium für Bildung und Forschung (BMBF) via the Deutsches Zentrum für Luft und Raumfahrt (DLR) under contract number 50 QV 0301. A. v.K. was supported by the Bundesministeriums für Wirtschaft und Technologie (BMWi) through DLR grant 50 OG 1101. S. M.B. acknowledges support from Science Foundation Ireland under grant 12/IP/1288.Part of the funding for GROND was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). “We acknowledge the excellent help in obtaining GROND data from Angela Hempel, Markus Rabus and Régis Lachaume on La Silla.
Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-based Cross-correlation Search in Advanced LIGO Data
We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using data from the first Advanced LIGO observing run. The search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specified coherence time, which can be adjusted to trade off sensitivity against computational cost. A search was conducted over the frequency range 25–, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates and simulated signal injections. The most stringent upper limit was set at , with comparable limits set across the most sensitive frequency range from 100 to . At this frequency, the 95% upper limit on the signal amplitude h 0 is marginalized over the unknown inclination angle of the neutron star's spin, and assuming the best orientation (which results in circularly polarized gravitational waves). These limits are a factor of 3–4 stronger than those set by other analyses of the same data, and a factor of ~7 stronger than the best upper limits set using data from Initial LIGO science runs. In the vicinity of , the limits are a factor of between 1.2 and 3.5 above the predictions of the torque balance model, depending on the inclination angle; if the most likely inclination angle of 44° is assumed, they are within a factor of 1.7