Detecting an association between Gamma Ray and Gravitational Wave Bursts

TL;DR

This paper proposes a model-independent method to detect correlations between gamma-ray bursts and gravitational wave bursts, enabling limits on gravitational wave amplitudes without detailed waveform knowledge.

Contribution

It introduces a new statistical approach to identify GWB-GRB associations that does not depend on waveform models or Gaussian noise assumptions.

Findings

Initial LIGO could exclude GWBs with $h_{RMS} \,\gtrsim\ 1.7\times 10^{-22}$ with 95% confidence after 1000 GRB observations.

The method does not require knowledge of the source waveform or Gaussian noise assumptions.

The limits improve with more observed GRBs.

Abstract

If $\gamma$-ray bursts (GRBs) are accompanied by gravitational wave bursts (GWBs) the correlated output of two gravitational wave detectors evaluated in the moments just prior to a GRB will differ from that evaluated at times not associated with a GRB. We can test for this difference independently of any model of the GWB signal waveform. If we invoke a model for the GRB source population and GWB radiation spectral density we can find a confidence interval or upper limit on the root-mean-square GWB signal amplitude in the detector waveband. To illustrate we adopt a simple, physically motivated model and estimate that initial LIGO detector observations coincident with 1000 GRBs could lead us to exclude, with 95% confidence, associated GWBs with $h_{RMS} \gtrsim 1.7 \times 10^{-22}$. This result does not require the detector noise be Gaussian or that any inter-detector correlated noise be measured or measurable; it does not require advanced or a priori knowledge of the source waveform; and the limits obtained on the wave-strength improve with the number of observed GRBs.