Dispersion measure variations and their effect on precision pulsar timing

4042 14 archive 337 disk0/00/00/40/42 2008-04-07 14:19:41 2008-07-18 10:48:28 2008-07-16 17:04:39 article show Aidan.Hotan@utas.edu.au You XP Hotan AW Aidan.Hotan@utas.edu.au Ord SM Jenet F Bhat NDR Teoh A Hobbs G Coles WA Manchester RN Edwards R Bailes M Sarkissian J Verbiest JPW van Straten W Dispersion measure variations and their effect on precision pulsar timing pub 240101 970102 780102 restricted pulsars: general – ISM: general. The definitive version is available at www.blackwell-synergy.com category => A1 categoryDesc => Refereed Article in a Scholarly Journal eprintID => 0 field1 => Monthly Notices of the Royal Astronomical Society field10 => field11 => field12 => field13 => field2 => "Oxford, England" field3 => 378 field4 => 2 field5 => 493-506 field6 => Blackwell Publishing field7 => 0035-8711 field8 => field9 => funding => Y grant => lastUpdate => 4/07/2007 rfcd => 240101 seo => 780102 themeArea => FT title => Dispersion measure variations and their effect on precision pulsar timing tor => PB uid => 45149 update => no We present an analysis of the variations seen in the dispersion measures (DMs) of 20-ms 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 characterized 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. 2007 published Monthly Notices of the Royal Astronomical Society 378 2 Blackwell Publishing 493-506 10.1111/j.1365-2966.2007.11617.x TRUE 0035-8711 http://dx.doi.org/10.1111/j.1365-2966.2007.11617.x 4800 3 4042 1 application/pdf en staffonly cc_utas

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