An Efficient Approximation to the Likelihood for Gravitational Wave Stochastic Background Detection Using Pulsar Timing Data

Understand

Direct detection of gravitational waves by pulsar timing arrays will become feasible over the next few years.

• In the low frequency regime ($10^{-7}$ Hz -- $10^{-9}$ Hz), we expect that a superposition of gravitational waves from many sources will manifest itself as an isotropic stochastic gravitational wave background.
• Currently, a number of techniques exist to detect such a signal; however, many detection methods are computationally challenging.
• Here we introduce an approximation to the full likelihood function for a pulsar timing array that results in computational savings proportional to the square of the number of pulsars in the array.