A. Singer
California Institute of Technology
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Physical Review D | 2017
B. Abbott; R. Abbott; M. R. Abernathy; R. Adhikari; S. Anderson; K. Arai; M. C. Araya; J. C. Barayoga; B. Barish; B. K. Berger; G. Billingsley; J. K. Blackburn; R. Bork; A. F. Brooks; C. Cahillane; T. Callister; C. Cepeda; R. Chakraborty; T. Chalermsongsak; P. Couvares; D. C. Coyne; V. Dergachev; R. W. P. Drever; P. Ehrens; T. Etzel; S. E. Gossan; K. E. Gushwa; E. K. Gustafson; E. D. Hall; A. W. Heptonstall
In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector’s differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector’s gravitational-wave response. The gravitational-wave response model is determined by the detector’s opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 days of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10° in phase across the relevant frequency band, 20 Hz to 1 kHz.
Physical Review D | 2017
B. Abbott; R. Abbott; R. Adhikari; A. Ananyeva; S. Anderson; S. Appert; K. Arai; M. C. Araya; J. C. Barayoga; B. C. Barish; B. K. Berger; G. Billingsley; J. K. Blackburn; R. Bork; A. F. Brooks; S. Brunett; C. Cahillane; T. A. Callister; C. B. Cepeda; P. Couvares; D. C. Coyne; R. W. P. Drever; P. Ehrens; J. Eichholz; T. Etzel; J. Feicht; E. M. Fries; S. E. Gossan; K. E. Gushwa; E. K. Gustafson
We report on an all-sky search for periodic gravitational waves in the frequency band 20–475 Hz and with a frequency time derivative in the range of [−1.0,+0.1]×10−8 Hz/s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our galaxy. This search uses the data from Advanced LIGO’s first observational run, O1. No periodic gravitational wave signals were observed, and upper limits were placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude h0 are ∼4×10−25 near 170 Hz. For a circularly polarized source (most favorable orientation), the smallest upper limits obtained are ∼1.5×10−25. These upper limits refer to all sky locations and the entire range of frequency derivative values. For a population-averaged ensemble of sky locations and stellar orientations, the lowest upper limits obtained for the strain amplitude are ∼2.5×10−25.
Physical Review D | 2017
B. Abbott; R. Abbott; R. Adhikari; A. Ananyeva; S. Anderson; S. Appert; K. Arai; M. C. Araya; J. C. Barayoga; B. C. Barish; B. K. Berger; G. Billingsley; J. K. Blackburn; R. Bork; A. F. Brooks; S. Brunett; C. Cahillane; T. A. Callister; C. B. Cepeda; P. Couvares; D. C. Coyne; Ronald W. P. Drever; P. Ehrens; J. Eichholz; T. Etzel; J. Feicht; E. M. Fries; S. E. Gossan; K. E. Gushwa; E. K. Gustafson
During their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100 M⊙, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93 Gpc^(−3) yr^(−1) in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits.