# On the free-precession candidate PSR B1828-11: Evidence for increasing deformation

 dc.identifier.uri http://dx.doi.org/10.15488/5193 dc.identifier.uri https://www.repo.uni-hannover.de/handle/123456789/5240 dc.contributor.author Ashton, G. dc.contributor.author Jones, D.I. dc.contributor.author Prix, Reinhard dc.date.accessioned 2019-08-15T11:13:37Z dc.date.available 2019-08-15T11:13:37Z dc.date.issued 2017 dc.identifier.citation Ashton, G.; Jones, D.I.; Prix, R.: On the free-precession candidate PSR B1828-11: Evidence for increasing deformation. In: Monthly Notices of the Royal Astronomical Society 465 (2017), Nr. 3, S. 164-178. DOI: https://doi.org/10.1093/mnras/stx060 dc.description.abstract We observe that the periodic variations in spin-down rate and beam-width of the radio pulsar PSR B1828-11 are getting faster. In the context of a free precession model, this corresponds to a decrease in the precession period $P_{\mathrm{fp}}$. We investigate how a precession model can account for such a decrease in $P_{\mathrm{fp}}$, in terms of an increase over time in the absolute biaxial deformation ($|\epsilon_{\mathrm{p}}|{\sim}10^{-8}$) of this pulsar. We perform a Bayesian model comparison against the 'base' precession model (with constant $\epsilon_{\mathrm{p}}$) developed in Ashton et al (2016), and we obtain decisive odds in favour of a time-varying deformation. We study two types of time-variation: (i) a linear drift with a posterior estimate of $\dot{\epsilon}_{\mathrm{p}}{\sim}10^{-18}\,\mathrm{s}^{-1}$ and odds of $10^{75}$ compared to the base-model, and (ii) $N$ discrete positive jumps in $\epsilon_{\mathrm{p}}$ with very similar odds to the linear $\epsilon_{\mathrm{p}}$-drift model. The physical mechanism explaining this behaviour is unclear, but the observation could provide a crucial probe of the interior physics of neutron stars. We also place an upper bound on the rate at which the precessional motion is damped, and translate this into a bound on a dissipative mutual friction-type coupling between the star's crust and core. eng dc.language.iso eng dc.publisher Oxford : Oxford University Press (OUP) dc.relation.ispartofseries Monthly Notices of the Royal Astronomical Society 465 (2017), Nr. 3 dc.rights CC BY 4.0 Unported dc.rights.uri https://creativecommons.org/licenses/by/4.0/ dc.subject Pulsar eng dc.subject Physics eng dc.subject Periodic graph (geometry) eng dc.subject Neutron star eng dc.subject Astrophysics eng dc.subject Deformation (mechanics) eng dc.subject Upper and lower bounds eng dc.subject Precession eng dc.subject.ddc 520 | Astronomie, Kartographie ger dc.title On the free-precession candidate PSR B1828-11: Evidence for increasing deformation dc.type Article dc.type Text dc.relation.issn 0035-8711 dc.relation.doi https://doi.org/10.1093/mnras/stx060 dc.bibliographicCitation.issue 3 dc.bibliographicCitation.volume 465 dc.bibliographicCitation.firstPage 164 dc.bibliographicCitation.lastPage 178 dc.description.version publishedVersion tib.accessRights frei zug�nglich
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