Current and future projects as part of the PPTA
The PPTA has the major goal of making a direct detection of low-frequency gravitational waves using pulsar timing observations. The data-sets being obtained for this goal also allow a large number of other scientific studies to be carried out. We provide below a summary of the research currently being carried out followed by possible future projects.
Our Publications page contains a list of current publications that are based on PPTA data or research for the PPTA project. Reviews of the PPTA projects and goals were published by Hobbs (2005) and Manchester (2006). We realised early in the project that our observations at ~700MHz will be significantly degraded by RFI from digital TV transmissions. Kesteven et al. (2005) showed how the effect of this RFI on our pulsar observations can be minimised using an adaptive filtering technique. Producing a hardware implementation of this idea is a a current project. It was essential to determine how many pulsars are required, how often to observe and the necessary timing precision to detect a stochastic background of gravitational waves. This was calculated by Jenet et al. (2005) and the current observing plan defined by these results. This paper showed that we need to be able to time ~20 pulsars with an rms timing precision significantly less than 1us. This required new methods to obtain arrival times using full polarization information (van Straten 2006) and new software for analysing the timing residuals (Hobbs et al. 2006, Edwards et al. 2006). Even though our current data-sets are not suitable for making a direct detection of gravitational waves we have used a statistically rigorous method to place limits on the existence on any such waves (Jenet et al. 2006). We show in Jenet et al. (2006) that the full PPTA data-sets is sensitive to the expected gravitational wave background from multiple sources including coalescing black-hole binary systems and cosmic strings.