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From spin noise to systematics: stochastic processes in the first International Pulsar Timing Array data release

L Lentati 1 R. M. Shannon 2 W. A. Coles 3 J. P. W. Verbiest 4 R van Haasteren 5 J.A. Ellis 5 R. N. Caballero 4 R. N. Manchester 2 Z. Arzoumanian 6 S. Babak 7 C.G Bassa 8 N.D.R. Bhat 9 P. Brem 7 M. Burgay 10 S. Burke-Spolaor 11 D. Champion 4 S. Chatterjee 12 Ismaël Cognard 13 J. M. Cordes 14 S. Dai 2 P. Demorest 14 G. Desvignes 13 T. Dolch 15 R. D. Ferdman 16 E. Fonseca 17 J. R. Gair 1 M.E. Gonzalez 18 E. Graikou 4 Lucas Guillemot 13 J. w. t. Hessels 8 G Hobbs 19 G. H. Janssen 20 G Jones 21 R Karuppusamy 4 M Keith 22 M Kerr 19 M Kramer 23 M.T Lam 14 P. D. Lasky 19 A Lassus 13 P Lazarus 7 T. J. W. Lazio 5 K.J. Lee 24 L. Levin 22 K. Liu 4 R. S. Lynch 8 D. R. Madison 25 J. Mckee 26 M Mclaughlin 27 S. T. Mcwilliams 27 C.M.F. Mingarelli 28 D.J. Nice 29 S. Osłowski 4 T. Pennucci 30 B. B. P. Perera 22 D. Perrodin 10 A Petiteau 31 P. Possenti 32 S.M. Ransom 25 D Reardon 19 P. A. Rosado 33 S. A. Sanidas 34 A Sesana 7 G. Shaifullah 4 X Siemens 35 R. Smits 20 I. Stairs 36 B. Stappers 22 D.R. Stinebring 37 K. Stowall 38 J.J. Swiggum 39 S.R. Taylor 5 Gilles Theureau 16 C. Tiburzi 10 L Toomey 19 M Vallisneri 5 W. van Straten 4 A Vecchio 40 J.B. Wang 41 Y. Wang 42 X.P. You 43 W.W. Zhu 13 X.-J Zhu 44
31 APC-Gravitation - APC - Gravitation
APC (UMR_7164) - AstroParticule et Cosmologie, AEI - Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut )
Abstract : We analyse the stochastic properties of the 49 pulsars that comprise the first International Pulsar Timing Array (IPTA) data release. We use Bayesian methodology, performing model selection to determine the optimal description of the stochastic signals present in each pulsar. In addition to spin-noise and dispersion-measure (DM) variations, these models can include timing noise unique to a single observing system, or frequency band. We show the improved radio-frequency coverage and presence of overlapping data from different observing systems in the IPTA data set enables us to separate both system and band-dependent effects with much greater efficacy than in the individual PTA data sets. For example, we show that PSR J1643−1224 has, in addition to DM variations, significant band-dependent noise that is coherent between PTAs which we interpret as coming from time-variable scattering or refraction in the ionised interstellar medium. Failing to model these different contributions appropriately can dramatically alter the astrophysical interpretation of the stochastic signals observed in the residuals. In some cases, the spectral exponent of the spin noise signal can vary from 1.6 to 4 depending upon the model, which has direct implications for the long-term sensitivity of the pulsar to a stochastic gravitational-wave (GW) background. By using a more appropriate model, however, we can greatly improve a pulsar's sensitivity to GWs. For example, including system and band-dependent signals in the PSR J0437−4715 data set improves the upper limit on a fiducial GW background by ∼ 60% compared to a model that includes DM variations and spin-noise only.
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Submitted on : Tuesday, January 31, 2017 - 1:19:25 PM
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L Lentati, R. M. Shannon, W. A. Coles, J. P. W. Verbiest, R van Haasteren, et al.. From spin noise to systematics: stochastic processes in the first International Pulsar Timing Array data release. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2016, 458 (2), pp.2161-2187. ⟨10.1093/mnras/stw395⟩. ⟨insu-01327914⟩



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