[Show abstract][Hide abstract] ABSTRACT: Analysis of pulsar timing data sets may provide the first direct
detection of gravitational waves. This paper, the third in a series
describing the mathematical framework implemented into the TEMPO2 pulsar
timing package, reports on using TEMPO2 to simulate the timing residuals
induced by gravitational waves. The TEMPO2 simulations can be used to
provide upper bounds on the amplitude of an isotropic, stochastic,
gravitational wave background in our Galaxy and to determine the
sensitivity of a given pulsar timing experiment to individual,
supermassive, binary black hole systems.
Monthly Notices of the Royal Astronomical Society 04/2009; 394(4):1945-1955. DOI:10.1111/j.1365-2966.2009.14391.x · 5.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We present an analysis of the variations seen in the dispersion measures (DMs) of 20 millisecond pulsars observed as part of the Parkes Pulsar Timing Array project. We carry out a statistically rigorous structure function analysis for each pulsar and show that the variations seen for most pulsars are consistent with those expected for an interstellar medium characterised by a Kolmogorov turbulence spectrum. The structure functions for PSRs J1045-4509 and J1909-3744 provide the first clear evidence for a large inner scale, possibly due to ion-neutral damping. We also show the effect of the solar wind on the DMs and show that the simple models presently implemented into pulsar timing packages cannot reliably correct for this effect. For the first time we clearly show how DM variations affect pulsar timing residuals and how they can be corrected in order to obtain the highest possible timing precision. Even with our presently limited data span, the residuals (and all parameters derived from the timing) for six of our pulsars have been significantly improved by correcting for the DM variations.
Monthly Notices of the Royal Astronomical Society 03/2007; 378(2). DOI:10.1111/j.1365-2966.2007.11617.x · 5.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tempo2 is a new pulsar timing package that provides the precision necessary for modern millisecond timing projects and should supersede all existing pulsar timing packages such as tempo and psrtime. As tempo2 is the only program available that can analyse multiple pulsar datasets simultaneously it will become an integral part of pulsar timing array projects which aim to detect the signatures of gravitational radiation in pulsar timing residuals. In this paper we describe the basic functionality of tempo2.
Chinese Journal of Astronomy and Astrophysics 12/2006; 6:189-192. DOI:10.1088/1009-9271/6/S2/35 · 0.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have detected the rare phenomenon of stable, drifting sub-pulse behaviour in two pulsars discovered in the recent Swinburne intermediate latitude pulsar survey. The pulsars, PSR and PSR J1919+0134, have approximate periods (P) of 1.873 and 1.6039 s respectively.
Both pulsars have multicomponent profiles, and distinct drifting is observed across them. We have identified a single drift mode in both pulsars: the drift rate for PSR being 5.4(1) ms P−1 and 5.8(2) ms P−1 for PSR 1919+0134. The drifting is linear across the profile with no departure from linearity at the edges within the sensitivity of our observations.
Monthly Notices of the Royal Astronomical Society 11/2001; 328(3):911 - 913. DOI:10.1046/j.1365-8711.2001.04946.x · 5.11 Impact Factor