A blind hierarchical coherent search for gravitational-wave signals from coalescing compact binaries in a network of interferometric detectors

Abstract

We describe a hierarchical data analysis pipeline for coherently searching for gravitational-wave signals from non-spinning compact binary coalescences (CBCs) in the data of multiple earth-based detectors. This search assumes no prior information on the sky position of the source or the time of occurrence of its transient signals and, hence, is termed 'blind'. The pipeline computes the coherent network search statistic that is optimal in stationary, Gaussian noise. More importantly, it allows for the computation of a suite of alternative multi-detector coherent search statistics and signal-based discriminators that can improve the performance of CBC searches in real data, which can be both non-stationary and non-Gaussian. Also, unlike the coincident multi-detector search statistics that have been employed so far, the coherent statistics are different in the sense that they check for the consistency of the signal amplitudes and phases in the different detectors with their different orientations and with the signal arrival times in them. Since the computation of coherent statistics entails searching in the sky, it is more expensive than that of the coincident statistics that do not require it. To reduce computational costs, the first stage of the hierarchical pipeline constructs coincidences of triggers from the multiple interferometers, by requiring their proximity in time and component masses. The second stage follows up on these coincident triggers by computing the coherent statistics. Here, we compare the performances of this hierarchical pipeline with and without the second (or coherent) stage in Gaussian noise. Although introducing hierarchy can be expected to cause some degradation in the detection efficiency compared to that of a single-stage coherent pipeline, nevertheless it improves the computational speed of the search considerably. The two main results of this work are as follows: (1) the performance of the hierarchical coherent pipeline on Gaussian data is shown to be better than the pipeline with just the coincident stage; (2) the three-site network of 0264-9381/11/134009+16$33.00

Earthquake Early Warning Using Future Generation Gravity Strainmeters

“…To compute the SNR, we consider detection via optimal matched filtering (Jaranowski & Królak, 2012), which is based on the cross correlation between the gravity data and a template of the expected gravity strain perturbation. Template-matching techniques have been widely used in modern seismology to detect earthquakes with low SNRs (Frank et al, 2014;Gibbons & Ringdal, 2006;Shelly et al, 2007) and in astrophysics to detect coalescing compact binaries (Bose et al, 2011;Pai et al, 2001).…”

Performance of particle swarm optimization on the fully-coherent all-sky search for gravitational waves from compact binary coalescences

“…For fixed {τ 0 , τ 1.5 , α, δ}, the maximization over t c , can be carried out very efficiently using the Fast Fourier Transform (FFT) since p|q(t − t c ) is a correlation operation [16]. We call (34) with Θ = {τ 0 , τ 1.5 , α, δ}, the coherent fitness function.…”

Gravitational-Wave Data Analysis. Formalism and Sample Applications: The Gaussian Case

“…Events from different detectors are deemed to be in coincidence if their ellipsoids have a nonzero overlap. The coincidence and the coherent strategies of multidetector detection of gravitational-wave signals from inspiralling compact binaries have been compared in [96, 97, 32]. [96] considered detectors in pairs located in the same site and [97] pairs of detectors at geographically separated sites.…”

“…[96] considered detectors in pairs located in the same site and [97] pairs of detectors at geographically separated sites. The case of three detectors (like the network of two LIGO detectors and the Virgo detector) has been considered in detail in [32], where it was demonstrated that the hierarchical coherent pipeline on Gaussian data has a better performance than the pipeline with just the coincident stage.…”