Search for Gravitational Waves Associated With Gamma-Ray Bursts During Ligo Science Run 6 and Virgo Science Runs 2 and 3

Abstract

We present the results of a search for gravitational waves associated with 154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments in 2009-2010, during the sixth LIGO science run and the second and third Virgo science runs. We perform two distinct searches: a modeled search for coalescences of either two neutron stars or a neutron star and black hole, and a search for generic, unmodeled gravitational-wave bursts. We find no evidence for gravitational-wave counterparts, either with any individual GRB in this sample or with the population as a whole. For all GRBs we place lower bounds on the distance to the progenitor, under the optimistic assumption of a gravitational-wave emission energy of 10 −2 M c 2 at 150 Hz, with a median limit of 17 Mpc. For short-hard GRBs we place exclusion distances on binary neutron star and neutron-star-black-hole progenitors, using astrophysically motivated priors on the source parameters, with median values of 16 Mpc and 28 Mpc, respectively. These distance limits, while significantly larger than for a search that is not aided by GRB satellite observations, are not large enough to expect a coincidence with a GRB. However, projecting these exclusions to the sensitivities of Advanced LIGO and Virgo, which should begin operation in 2015, we find that the detection of gravitational waves associated with GRBs will become quite possible.

Methods and results of a search for gravitational waves associated with gamma-ray bursts using the GEO 600, LIGO, and Virgo detectors

“…5. To test the sample of GRBs for a population of subthreshold GW signals, we use a weighted binomial test to check that the distribution of p-values is compatible with the uniform distribution expected from the null hypothesis (see Appendix A of [27] for details). The test yields a background probability of 19.3%, which indicates that the distribution is consistent with no GW events being present.…”

“…The coherent analysis algorithm used in this search is X-PIPELINE [67], and the overall search procedure follows that used in previous searches for generic GW signals during the S5-VSR1 [26] and S6-VSR2,3 [27] science runs. 1 Following the method of the S6-VSR2,3 search, we employ a circularly polarized GW signal model; this is motivated by our expectation that the rotation axis of the GRB central engine is likely pointed at the observer, to within ∼10°.…”

“…Second, and more significantly, an error in the sky location will lead to an erroneous time shift of the detector data vectors when synchronizing the arrival time of a GW 1 The most recent searches for short-duration GWs associated with GRBs have included a modeled search for CBC signals (either NS-NS or NS-BH) on the short GRBs included in the sample [27,32]. Due to the sensitivity of the GEO 600 detector at low frequencies (where most of the power of a CBC waveform is emitted) we did not perform a dedicated search for CBCs as part of our analysis.…”

“…Previously, searches for GWs associated with GRBs were performed on approximately 500 GRBs which occurred during times when at least two of the LIGO and Virgo detectors were collecting data [17,18,[25][26][27]. Related analyses have searched for extended-duration GW signals associated with long GRBs [28], and for GWs arising from the oscillation of neutron star f-modes in magnetars and soft gamma-ray repeaters [29][30][31].…”

Pair fireball precursors of neutron star mergers

“…Their limited durations allow for an unambiguous time association with the GW chirp (Abadie et al 2012), while extant satellites, including Swift, Fermi, and Integral, provide nearly continuous coverage of the hard X-ray and gamma-ray sky. Their major drawback, however, is that the relativistic jet is believed to be confined to a narrow solid angle; due to relativistic beaming, only observers within the opening angle of the jet observe the gamma-ray emission and its synchrotron X-ray and optical afterglow.…”