The cross-correlation search for a hot spot of gravitational waves

TL;DR

This paper explores using cross-correlation methods to detect gravitational wave signals from small sky regions, like the Virgo cluster, by analyzing detector pairs over extended periods, enhancing detection prospects for continuous GW sources.

Contribution

It demonstrates how cross-correlation can be optimized for small sky regions and evaluates detection feasibility for the Virgo cluster with current and future detector networks.

Findings

Detection of GW signals from the Virgo cluster is feasible with about a year's data.

Multibaseline searches improve sensitivity and detection prospects.

The method can be applied to other hot spots and detector pairs.

Abstract

The cross-correlation search has been previously applied to map the gravitational wave (GW) stochastic background in the sky and also to target GW from rotating neutron stars/pulsars. Here we investigate how the cross-correlation method can be used to target a small region in the sky spanning at most a few pixels, where a pixel in the sky is determined by the diffraction limit which depends on the (i) baseline joining a pair of detectors and (ii) detector bandwidth. Here as one of the promising targets, we consider the Virgo cluster - a "hot spot" spanning few pixels - which could contain, as estimates suggest $\sim 10^{11}$ neutron stars, of which a small fraction would continuously emit GW in the bandwidth of the detectors. For the detector baselines, we consider advanced detector pairs among LCGT, LIGO, Virgo, ET etc. Our results show that sufficient signal to noise can be accumulated with integration times of the order of a year. The results improve for the multibaseline search. This analysis could as well be applied to other likely hot spots in the sky and other possible pairs of detectors.