1201.3573 (Matthew Pitkin)

Extending burst searches with pulsar timing arrays    [PDF]

Matthew Pitkin

Pulsar timing arrays (PTAs) are being used to search for very low frequency gravitational waves. Gravitational waves imprint their signal in the observed pulse time of arrivals from when they passed the pulsar and as they pass the Earth. In searches for gravitational wave bursts with PTAs (e.g. Finn & Lommen, 2010) the pulsar term is generally ignored as only the Earth term will be coherent between all pulsars in the array, whereas signals in the pulsar terms may be separated by delays on the order of the pulsar distance. However, we show that for a set of pulsars (made up from those in the International Pulsar Timing Array) there are areas of the sky where the alignment between pairs, or more, of pulsars and a source are serendipitously placed to give pulsar terms that are separated by feasible (10-20 year) observing times. The data from these pulsars can therefore be coherently combined, with the appropriate sky position delay, to search for gravitational wave bursts. This increases the time-span over which bursts could be observed to be many times that covered by the PTA observation span. Assuming perfectly known pulsar distances we show that sources over approximately 70 per cent of the sky produce pulsar term signals separated by less than 10 years within at least one pair of pulsars. We study the effect of pulsar distance uncertainties on the sky coverage. We also assess a simplified method for detecting burst sources from these sky positions with a toy two-pulsar array.

View original: http://arxiv.org/abs/1201.3573