The cross-correlation search for a hot spot of gravitational waves : Numerical study for point spread function

The cross-correlation search for gravitational waves, also known as 'radiometry', has been previously applied to map the gravitational wave stochastic background in the sky and also to target gravitational waves from rotating neutron stars/pulsars. We consider the Virgo cluster which may appear as a 'hot spot' spanning few pixels in the sky in a radiometry analysis. Our results show that sufficient signal to noise ratio can be accumulated with integration times of the order of a year. We also present a numerical simulation of radiometric analysis, assuming ground-based detectors which are currently under construction or being upgraded. The point spread function of the injected sources is confirmed by numerical tests. The typical resolution of radiometry analysis is a few square degrees, as compared to the several thousand pixels for the full sky in an all-sky map.