Status of the LIGO detectors
TL;DR: All three LIGO detectors have reached sensitivities within a factor of 2 of design over a wide range of frequencies, achieving sky-averaged detection range (SNR > 8) of more than 10 Mpc for inspiral binary neutron stars with masses of 1.4 Msol with the best instrument as discussed by the authors.
Abstract: All three LIGO detectors have reached sensitivities within a factor of 2 of design over a wide range of frequencies. A sky-averaged detection range (SNR > 8) of more than 10 Mpc for inspiral binary neutron stars with masses of 1.4 Msol has been achieved with the best instrument. The fourth LIGO science run taking data for 30 days has been completed earlier this year with a triple coincidence duty cycle greater than 50%. A commissioning effort to scale up the cavity powers to design sensitivity as well as preparations for an extended science run is underway. The data from the first two science runs were fully analysed and results are summarized.
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TL;DR: In this paper, Kalogera et al. presented an up-to-date summary of the rates for all types of compact binary coalescence sources detectable by the initial and advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo.
Abstract: We present an up-to-date, comprehensive summary of the rates for all types of compact binary coalescence sources detectable by the initial and advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo. Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters and are still uncertain. The most confident among these estimates are the rate predictions for coalescing binary neutron stars which are based on extrapolations from observed binary pulsars in our galaxy. These yield a likely coalescence rate of 100 Myr−1 per Milky Way Equivalent Galaxy (MWEG), although the rate could plausibly range from 1 Myr−1 MWEG−1 to 1000 Myr−1 MWEG−1 (Kalogera et al 2004 Astrophys. J. 601 L179; Kalogera et al 2004 Astrophys. J. 614 L137 (erratum)). We convert coalescence rates into detection rates based on data from the LIGO S5 and Virgo VSR2 science runs and projected sensitivities for our advanced detectors. Using the detector sensitivities derived from these data, we find a likely detection rate of 0.02 per year for Initial LIGO–Virgo interferometers, with a plausible range between 2 × 10−4 and 0.2 per year. The likely binary neutron–star detection rate for the Advanced LIGO–Virgo network increases to 40 events per year, with a range between 0.4 and 400 per year.
1,011 citations
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TL;DR: LCGT as discussed by the authors is the first detector with an advanced technique for employing a cryogenic mirror in order to first detect a gravitational wave, and after detection, the detector will serve as an astronomical tool to observe the Universe through gravitational wave radiation.
Abstract: LCGT shall be planned to be the first-generation detector with an advanced technique for employing a cryogenic mirror in order to firstly detect a gravitational wave, and after detection, the detector will serve as an astronomical tool to observe the Universe through gravitational wave radiation. In collaborative observation with the LIGO, GEO and Virgo projects, LCGT desires to contribute to the enterprise of detecting gravitational wave events by earlier funding. This paper summarizes the LCGT project.
248 citations
TL;DR: In this article, the authors review the current knowledge of the coalescence rates and the mass and spin distributions of merging neutron-star and black-hole binaries and emphasize the bi-directional connection between gravitational-wave astronomy and conventional astrophysics.
Abstract: As the ground-based gravitational-wave telescopes LIGO, Virgo and GEO 600 approach the era of first detections, we review the current knowledge of the coalescence rates and the mass and spin distributions of merging neutron-star and black-hole binaries. We emphasize the bi-directional connection between gravitational-wave astronomy and conventional astrophysics. Astrophysical input will make possible informed decisions about optimal detector configurations and search techniques. Meanwhile, rate upper limits, detected merger rates and the distribution of masses and spins measured by gravitational-wave searches will constrain astrophysical parameters through comparisons with astrophysical models. Future developments necessary to the success of gravitational-wave astronomy are discussed.
177 citations
TL;DR: In this article, the authors perform an end-to-end simulation that focuses on the detection and identification of binary mergers in the strong-field gravity regime, and demonstrate how construction of low-latency GW volumes in conjunction with local universe galaxy catalogs can solve the problem of false positives.
Abstract: Combined gravitational-wave (GW) and electromagnetic (EM) observations of compact binary mergers should enable detailed studies of astrophysical processes in the strong-field gravity regime. Networks of GW interferometers have poor angular resolution on the sky and their EM signatures are predicted to be faint. Therefore, a challenging goal will be to unambiguously pinpoint the EM counterparts to GW mergers. We perform the first comprehensive end-to-end simulation that focuses on: i) GW sky localization, distance measures and volume errors with two compact binary populations and four different GW networks, ii) subsequent detectability by a slew of multiwavelength telescopes and, iii) final identification of the merger counterpart amidst a sea of possible astrophysical false-positives. First, we find that double neutron star (NS) binary mergers can be detected out to a maximum distance of 400 Mpc (or 750 Mpc) by three (or five) detector GW networks respectively. NS -- black-hole (BH) mergers can be detected a factor of 1.5 further out. The sky localization uncertainties for NS-BH mergers are 50--170 sq. deg. (or 6--65 sq. deg.) for a three (or five detector) GW network respectively. Second, we quantify relative fractions of optical counterparts that are detectable by different size telescopes. Third, we present five case studies to illustrate the diversity of challenges in secure identification of the EM counterpart at low and high Galactic latitudes. For the first time, we demonstrate how construction of low-latency GW volumes in conjunction with local universe galaxy catalogs can help solve the problem of false positives.
172 citations
TL;DR: In this paper, a conceptual design for a 2-band xylophone configuration for a third-generation GW observatory, composed of a high-power, high-frequency interferometer and a cryogenic low-power low-frequency instrument, is presented.
Abstract: Achieving the demanding sensitivity and bandwidth, envisaged for third-generation gravitational wave (GW) observatories, is extremely challenging with a single broadband interferometer. Very high optical powers (megawatts) are required to reduce the quantum noise contribution at high frequencies, while the interferometer mirrors have to be cooled to cryogenic temperatures in order to reduce thermal noise sources at low frequencies. To resolve this potential conflict of cryogenic test masses with high thermal load, we present a conceptual design for a 2-band xylophone configuration for a third-generation GW observatory, composed of a high-power, high-frequency interferometer and a cryogenic low-power, low-frequency instrument. Featuring inspiral ranges of 3200 Mpc and 38 000 Mpc for binary neutron stars and binary black holes coalesences, respectively, we find that the potential sensitivity of xylophone configurations can be significantly wider and better than what is possible in a single broadband interferometer.
169 citations
References
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TL;DR: The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy.
Abstract: The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics of gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998.
2,032 citations
"Status of the LIGO detectors" refers background in this paper
...The LIGO gravitational wave detectors are Michelson interferometers which deploy arm cavities and power-recycling [1, 2]....
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TL;DR: The idea of gravitational waves was already implicit in the 1905 special theory of relativity, with its finite limiting speed for information transfer as mentioned in this paper, and the explicit formulation for gravitational waves in general relativity was put forward by Einstein in 1916 and 1918.
Abstract: The idea of gravitational waves was already implicit in the 1905 special theory of relativity, with its finite limiting speed for information transfer. The explicit formulation for gravitational waves in general relativity was put forward by Einstein in 1916 and 1918. He showed that the acceleration of masses generates time‐dependent gravitational fields that propagate away from their sources at the speed of light as warpages of spacetime. Such a propagating warpage is called a gravitational wave. Large detectors on opposite sides of the country are about to start monitoring the cosmos for the gravitational waves that general relativity tells us should be emanating from catastrophic astrophysical events.
367 citations
21 Jan 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis.
Abstract: For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.
268 citations
TL;DR: In this paper, conditions on the background fields from requiring finiteness, conformal invariance, anomally cancellation and unbroken supersymmetry are derived and compared, and consistency between these conditions fixes an ambiguity in the torsion Bianchi identity.
259 citations