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

J. Aasi et al. (LIGO Scientific Collaboration and Virgo Collaboration)

Phys. Rev. D 89, 122004 – Published 25 June 2014

Abstract

In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz–1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO 600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyze GRB events with large sky localization uncertainties, for example the localizations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well localized, due to the corrections required for the difference in arrival time between detectors. Using a linear search grid we are able to reduce the computational cost of the analysis by a factor of $O (10)$ for GBM events. Furthermore, we demonstrate that our analysis pipeline can improve upon the sky localization of GRBs detected by the GBM, if a high-frequency GW signal is observed in coincidence. We use the method of the linear grid in a search for GWs associated with 129 GRBs observed satellite-based gamma-ray experiments between 2006 and 2011. The GRBs in our sample had not been previously analyzed for GW counterparts. A fraction of our GRB events are analyzed using data from GEO 600 while the detector was using squeezed-light states to improve its sensitivity; this is the first search for GWs using data from a squeezed-light interferometric observatory. We find no evidence for GW signals, either with any individual GRB in this sample or with the population as a whole. For each GRB we place lower bounds on the distance to the progenitor, under an assumption of a fixed GW emission energy of $10^{- 2} M ⊙ c^{2}$ , with a median exclusion distance of 0.8 Mpc for emission at 500 Hz and 0.3 Mpc at 1 kHz. The reduced computational cost associated with a linear search grid will enable rapid searches for GWs associated with Fermi GBM events once the advanced LIGO and Virgo detectors begin operation.

Received 23 May 2014

DOI:https://doi.org/10.1103/PhysRevD.89.122004

Authors & Affiliations

Click to Expand

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 89, Iss. 12 — 15 June 2014

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Strain sensitivity for the detectors used in this analysis. GEO 600 is shown at two epochs from the S5 and S6 science runs.
Reuse & Permissions
Figure 2
Example linear (blue circles) and circular (black crosses) grids for a search for GW signals up to 1792 Hz. The localization for the Fermi GBM event GRB 080906B is shown. The linear search grid contains 41 sky positions, arranged in the direction of the gradient of the time shift been the H2 and G1 detectors. The circular grid contains 1324 sky positions and would require several days to analyze on a massively parallel computing cluster. Both search grids cover the 95% containment region for the GBM sky location probability distribution. The GBM statistical error for this event is 1.6°.
Reuse & Permissions
Figure 3
Sky localization using the linear search grid. The X-Pipeline analysis will localize a detected GW signal to the point on the linear grid closest to the true injected signal, within errors due to noise fluctuations. The containment distance is a function of the frequency and duration of the GW signal, and can be empirically measured for each GRB as part of the GW analysis pipeline; no additional processing time is required. In this example, the $2 σ$ containment distance is about 2.5°. The coordinates of the shaded region can be disseminated to electromagnetic (EM) astronomers for follow-up by wide-field telescopes.
Reuse & Permissions
Figure 4
Errors in sky localization reconstruction, for a simulated GBM event in real GW detector data with the H1-V1 detector network. For each frequency, six hundred sine-Gaussian waveforms with quality factor $Q = 9$ were analyzed using a linear grid covering a 16.5° uncertainty region with 59 grid points. The sky location of each simulation was jittered following a Fisher distribution with $σ = 1 0^{°}$ , and the amplitude was chosen to correspond to the 90% detection threshold. The one-dimensional error in the reconstructed location was measured along the axis of the search grid. High-frequency waveforms provide greater sensitivity to the time-of-arrival correction across the search grid.
Reuse & Permissions
Figure 5
Cumulative p-value distribution from the analysis of 129 GRBs. The dashed line gives the expected distribution under the null hypothesis. The most significant on-source event, with $p = 0.001$ , is associated with GRB 080816A; a study of detector data at the time of the event yields potential instrumental causes for the signal in the GW channel. The probability that our cumulative distribution is due to background is 19.3%, which indicates that the data is consistent with no subthreshold GW events being present.
Reuse & Permissions

Physical Review D

covering particles, fields, gravitation, and cosmology