Toward finding gravitational-wave signals from progenitors of short hard gamma-ray bursts and orphaned afterglows

Abstract

With multiple observatories and missions being planned for detecting orphaned afterglows associated with gamma-ray bursts (GRBs) we emphasize the importance of developing data analysis strategies for searching their possible counterpart signals in the data of gravitational wave (GW) detectors in the advanced detector era. This is especially attractive since short hard gamma-ray bursts (SGRBs) may have compact binary coalescences involving neutron stars (CBCNSs) as their progenitors, which emit gravitational waves. Joint electromagnetic (EM) and GW observations of these objects will enrich our understanding of their beaming, energetics, galactic environment, and shed light on a host of other outstanding questions related to them. Here we recognize some of the astrophysical factors that determine what fraction of CBCNS sources can generate orphaned afterglows. Pipelines already exist that target the sky-position and time of occurrence of SGRBs, known from EM observations, to search for their counterparts in GW detector data. Modifying them to analyse extended periods of time in the GW data in the past of the afterglow detection, while targeting a single sky-position, can search for GWs from the common progenitor. We assess the improvement in GW detectability to be had from utilizing the sky-position information. We also propose a method for improving the detection efficiency of targeted searches of GW signals from the putative CBCNS sources of afterglows and short gamma ray bursts in the presence of errors in detector calibration or CBCNS waveform models used in the search. The improvement arises from searching in a wider patch of the sky even when the sky-position is known accurately from EM observations and utilizes the covariance of the errors in waveform parameters with those in the sky position.

Revisiting Coincidence Rate Between Gravitational Wave Detection and Short Gamma-Ray Burst for the Advanced and Third Generation

“…For each coalescence we must first determine if its resultant GW emission is detectable. For this purpose we calculate the event's coherent signal-to-noise ratio (SNR), for the detector network, in the ideal case of Gaussian noise (see Ghosh & Bose (2013) for a more sophisticated scenario including the possibility of false alarms).…”

Measuring the Hubble constant: Gravitational wave observations meet galaxy clustering

“…A geometric explanation for this weighting function is given in Ref. [55]. (Additionally, we compute the network SNR of each source, and the average network SNR in each distance bin, which is used in the distance error estimation described below.)…”

“…In the figure one can see that the weight drops substantially beyond a distance of ∼2000 Mpc. This drop occurs because of the SNR threshold we set on the GW events [55].…”

Random projections in gravitational wave searches of compact binaries

“…The direct detections of gravitational waves (GWs) from the mergers of black holes and neutron stars [1][2][3][4][5][6] by Advanced LIGO (aLIGO) [7] and Advanced Virgo (AdV) [8] detectors in the first and second observing runs (O1 and O2, respectively) have launched the era of GW astronomy [9,10]. In the coming years, the global network of ground-based detectors, comprising aLIGO, AdV, KAGRA [11] and LIGO-India [12] will not only increase the detection rate and facilitate the search for their possible electromagnetic counterparts [13][14][15] but also produce an unprecedentedly large amount of data, which can pose an interesting computational challenge for GW data analysis.…”