Abstract
We present the results from three gravitational-wave searches for coalescing compact binaries with component masses above 1$\mathrm{M}_\odot$ during the first and second observing runs of the Advanced gravitational-wave detector network. During the first observing run (O1), from September $12^\mathrm{th}$, 2015 to January $19^\mathrm{th}$, 2016, gravitational waves from three binary black hole mergers were detected. The second observing run (O2), which ran from November $30^\mathrm{th}$, 2016 to August $25^\mathrm{th}$, 2017, saw the first detection of gravitational waves from a binary neutron star inspiral, in addition to the observation of gravitational waves from a total of seven binary black hole mergers, four of which we report here for the first time: GW170729, GW170809, GW170818 and GW170823. For all significant gravitational-wave events, we provide estimates of the source properties. The detected binary black holes have total masses between $18.6_{-0.7}^{+3.2}\mathrm{M}_\odot$, and $84.4_{-11.1}^{+15.8} \mathrm{M}_\odot$, and range in distance between $320_{-110}^{+120}$ Mpc and $2840_{-1360}^{+1400}$ Mpc. No neutron star - black hole mergers were detected. In addition to highly significant gravitational-wave events, we also provide a list of marginal event candidates with an estimated false alarm rate less than 1 per 30 days. From these results over the first two observing runs, which include approximately one gravitational-wave detection per 15 days of data searched, we infer merger rates at the 90% confidence intervals of $110\, -\, 3840$ $\mathrm{Gpc}^{-3}\,\mathrm{y}^{-1}$ for binary neutron stars and $9.7\, -\, 101$ $\mathrm{Gpc}^{-3}\,\mathrm{y}^{-1}$ for binary black holes assuming fixed population distributions, and determine a neutron star - black hole merger rate 90% upper limit of $610$ $\mathrm{Gpc}^{-3}\,\mathrm{y}^{-1}$.
Highlights
The first observing run (O1) of Advanced LIGO, which took place from September 12, 2015 until January 19, 2016, saw the first detections of gravitational waves (GWs) from stellar-mass binary black holes (BBHs) [1,2,3,4]
The second observing run (O2), which ran from November 30, 2016 to August 25, 2017, saw the first detection of gravitational waves from a binary neutron star inspiral, in addition to the observation of gravitational waves from a total of seven binary black hole mergers, four of which we report here for the first time: GW170729, GW170809, GW170818, and GW170823
Across the entirety of O1 and O2, the binary neutron star inspiral GW170817 remains the event with the highest network signal-to-noise ratio (SNR) and is assigned the most stringent possible bound on its false-alarm rate (FAR) by PyCBC and the highest value of L of any event in the combined O1 and O2 dataset by GstLAL
Summary
The first observing run (O1) of Advanced LIGO, which took place from September 12, 2015 until January 19, 2016, saw the first detections of gravitational waves (GWs) from stellar-mass binary black holes (BBHs) [1,2,3,4]. Gravitational waves from compact binaries carry information about the properties of the source such as the masses and spins These can be extracted via Bayesian inference by using theoretical models of the GW signal that describe the inspiral, merger, and ringdown of the final object for BBH [23,24,25,26,27,28,29,30] and the inspiral (and merger) for BNS [31,32,33]. We provide updated parameter estimates which exploit refined instrumental calibration, noise subtraction (for O2 data) [51,52], and updated amplitude power spectral density estimates [53,54] The observation of these GW events allows us to place constraints on the rates of stellar-mass BBH and BNS mergers in the Universe and probe their mass and spin distributions, putting them into astrophysical context. A variety of additional information on each event, data products including strain data and posterior samples, and postprocessing tools can be obtained from the accompanying data release [56] hosted by the Gravitational Wave Open Science Center [57]
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