Observing gravitational-wave transient GW150914 with minimal assumptions

Abstract

The gravitational-wave signal GW150914 was first identified on September 14, 2015, by searches forshort-duration gravitational-wave transients. These searches identify time-correlated transients in multipledetectors with minimal assumptions about the signal morphology, allowing them to be sensitive togravitational waves emitted by a wide range of sources including binary black hole mergers. Over theobservational period from September 12 to October 20, 2015, these transient searches were sensitive tobinary black hole mergers similar to GW150914 to an average distance of ∼600 Mpc. In this paper, wedescribe the analyses that first detected GW150914 as well as the parameter estimation and waveformreconstruction techniques that initially identified GW150914 as the merger of two black holes.We find thatthe reconstructed waveform is consistent with the signal from a binary black hole merger with a chirp massof ∼30 M⊙ and a total mass before merger of ∼70 M⊙ in the detector frame.