Probing a Stochastic Gravitational Wave Background using a Network of Laser Interferometric Detectors

Gravitational Wave (GW) detectors are coming close to the long awaited direct detection of sources. LIGO and Virgo detectors are operating at either better or close to their first generation goal sensitivity. More ground based and space based detectors are also expected in a decade. An exciting new window of astronomy is about to be opened.

GW astronomy aims to probe different kinds of sources, Stochastic Gravitational Wave Background (SGWB) is one of the most interesting ones. The universe is expected to have an SGWB generated by unmodeled/unresolved astrophysical and cosmological sources. Statistically isotropic cosmological SGWB has already caught lot of attention, as it is a direct probe of slow roll inflation. On the other hand, anisotropic SGWB, generated by unmodeled/unresolved astrophysical sources in the nearby universe, dominates the background by several orders of magnitude and can provide important information about the nearby universe not accessible to electro-magnetic astronomy. A gravitational wave radiometer algorithm is well suited for probing SGWB. We present a general analysis framework to efficiently probe SGWB in any given basis using a network of detectors. The special cases of isotropic, pixel basis and spherical harmonic basis have been implemented to analyze data from the LIGO-Virgo detectors. These analysis methods also provide a convenient way to characterize the efficiency of a detector network, which could be important for choosing the location and orientation of new detectors.