Aims of the PPTA project

This page is under construction

The PPTA data-sets allow (or will allow) us to study a wide variety of physical problems. Such problems range from looking for irregularities in terrestrial time standards to studying the early Universe. Our data-sets currently consist of approximately 2.5 years of timing observations of 20 millisecond pulsars. For each pulsar we record pulse times-of-arrival (TOAs) approximately once every two weeks at three observing frequencies (10, 20 and 50cm). A dual-band receiver allows us to observe at 10cm and 50cm simultaneously. We use standard pulsar timing techniques to obtain pulsar timing residuals from the TOAs using estimated astrometric, rotational, dispersion and binary parameters for each pulsar. The rms timing residuals for our pulsars currently lie between 100ns and 1us. The aim of the PPTA project is to obtain 5 year data-sets for 20 pulsars with the rms timing residuals for 10 pulsars close to 100ns and the remainder ~500ns.

We expect that the data-sets will allow us to:

• Detect (or limit) the existence of a stochastic background of low-frequency gravitational waves from the early Universe leading to constraints on the rate of expansion in the inflationary era.
• Provide an upper-bound on the dimensionless tension of a cosmic string background
• Constrain the merger rate of supermassive binary black hole systems at high red shift and rule out some relationships between the black hole mass and the galactic halo mass.
• Limit the existence of single coalescing massive black-hole binary systems
• Limit the existence of burst sources of gravitational waves
• Place limits on alternate theories of gravity
• Study pulsar timing irregularities
• Probe the structure of the interstellar medium between the pulsar and the Earth
• Improve planetary masses and check the Solar system planetary ephemeris
• Analyse the Solar corona and (perhaps) other Solar system objects (such as comets)
• Search for irregularities in the terrestrial time standards