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Publications (3)11.93 Total impact

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    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. · 5.52 Impact Factor
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    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; · 5.52 Impact Factor
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    G. Hobbs, R. Edwards, R. Manchester
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    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 01/2006; 6:189-192. · 0.89 Impact Factor