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

Lentati, L. and Mingarelli, C. M. F. (2016) From spin noise to systematics: stochastic processes in the first International Pulsar Timing Array data release. Monthly Notices of the Royal Astronomical Society, 458 (2). pp. 2161-2187. ISSN 0035-8711.

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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 pulsar timing array (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 ionized 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 per cent compared to a model that includes DM variations and spin-noise only.

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Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 February 16. Received 2016 February 16. In original form 2015 December 24. First published online February 19, 2016. The NANOGrav project receives support from National Science Foundation (NSF) PIRE program award number 0968296 and NSF Physics Frontier Center award number 1430284. The National Radio Astronomy Observatory is a facility of the NSF operated under cooperative agreement by Associated Universities, Inc. The Arecibo Observatory is operated by SRI International under a cooperative agreement with the NSF (AST-1100968), and in alliance with Ana G. Méndez-Universidad Metropolitana, and the Universities Space Research Association. The WSRT is operated by the Netherlands Institute for Radio Astronomy (ASTRON) with support from The Netherlands Foundation for Scientific Research NWO. The 100-m Effelsberg Radio Telescope is operated by the Max-Planck-Institut fur Radioastronomie at Effelsberg. Some of the work reported in this paper was supported by the ERC Advanced Grant ‘LEAP’, Grant Agreement Number 227947 (PI Kramer). Pulsar research at the Jodrell Bank Centre for Astrophysics is supported by a consolidated grant from STFC. The Parkes radio telescope is part of the Australia Telescope National Facility which is funded by the Commonwealth of Australia for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organization. LL was supported by a Junior Research Fellowship at Trinity Hall College, Cambridge University. CGB acknowledges support from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement no. 337062 (DRAGNET; PI Hessels) NDRB is supported by a Curtin Research Fellowship. RNC acknowledges the support of the International Max Planck Research School Bonn/Cologne and the Bonn-Cologne Graduate School. JG's work is supported by the Royal Society. MEG was partly funded by an NSERC PDF award. JAE acknowledges support by NASA through Einstein Fellowship grant PF4-150120. JWTH acknowledges funding from an NWO Vidi fellowship and ERC Starting Grant ‘DRAGNET’ (337062). GH is supported by an ARC Future Fellowship grant. RK acknowledges the support of the ERC Advanced Grant “LEAP (Number 227947, PI Kramer). PDL is supported by the Australian Research Council Discovery Project DP140102578. PL acknowledges the support of IMPRS Bonn/Cologne KJL gratefully acknowledges support from National Basic Research Program of China, 973 Program, 2015CB857101 and NSFC 11373011. KL acknowledges the support of the ERC Advanced Grant “LEAP” (Number 227947, PI Kramer). KL acknowledges the financial support by the European Research Council for the ERC Synergy Grant BlackHoleCam under contract no. 610058. CMFM was supported by a Marie Curie International Outgoing Fellowship within the European Union Seventh Framework Programme. SO is supported by the Alexander von Humboldt Foundation. PAR is supported by the Australian Research Council Discovery Project DP140102578. SAS acknowledges support from an NWO Vidi fellowship (PI: Hessels). AS is supported by a University Research Fellowship of the Royal Society. RMS acknowledges travel support through a John Philip early career research award from CSIRO. Pulsar research at UBC is supported by an NSERC Discovery Grant and Discovery Accelerator Supplement and by the Canadian Institute for Advanced Research. SRT is supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Oak Ridge Associated Universities through a contract with NASA. MV acknowledges support from the JPL RTD programme. Portions of this research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. RvH acknowledges support by NASA through Einstein Fellowship grant PF3-140116. JBW is supported by West Light Foundation of CAS XBBS201322 and NSFC project no.11403086. YW was supported by the National Science Foundation of China (NSFC) award number 11503007. XPY acknowledges support by NNSF of China (U1231120) and FRFCU (XDJK2015B012).
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
European Research Council (ERC)227947
Science and Technology Facilities Council (STFC)UNSPECIFIED
Trinity Hall College, Cambridge University UNSPECIFIED
European Research Council (ERC)337062
Curtin Research FellowshipUNSPECIFIED
International Max Planck Research School (IMPRS) for Astronomy and AstrophysicsUNSPECIFIED
Bonn-Cologne Graduate School of Physics and AstronomyUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
NASA Einstein FellowshipPF4-150120
Australian Research CouncilDP140102578
National Basic Research Program of China 973 Program2015CB857101
National Natural Science Foundation of China11373011
European Research Council (ERC)610058
Marie Curie FellowshipUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Commonwealth Scientific and Research Organization (CSIRO)UNSPECIFIED
Canadian Institute for Advanced Research (CIAR)UNSPECIFIED
NASA Einstein FellowshipPF3-140116
Chinese Academy of Sciences West Light FoundationXBBS201322
National Natural Science Foundation of China11403086
National Natural Science Foundation of China11503007
National Natural Science Foundation of ChinaU1231120
Fundamental Research Funds for the Central Universities (FRFCU)XDJK2015B012
Subject Keywords:methods: data analysis pulsars: general
Record Number:CaltechAUTHORS:20160603-100518456
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Official Citation:L. Lentati, R. M. Shannon, W. A. Coles, J. P. W. Verbiest, R. van Haasteren, J. A. Ellis, R. N. Caballero, R. N. Manchester, Z. Arzoumanian, S. Babak, C. G. Bassa, N. D. R. Bhat, P. Brem, M. Burgay, S. Burke-Spolaor, D. Champion, S. Chatterjee, I. Cognard, J. M. Cordes, S. Dai, P. Demorest, G. Desvignes, T. Dolch, R. D. Ferdman, E. Fonseca, J. R. Gair, M. E. Gonzalez, E. Graikou, L. Guillemot, J. W. T. Hessels, G. Hobbs, G. H. Janssen, G. Jones, R. Karuppusamy, M. Keith, M. Kerr, M. Kramer, M. T. Lam, P. D. Lasky, A. Lassus, P. Lazarus, T. J. W. Lazio, K. J. Lee, L. Levin, K. Liu, R. S. Lynch, D. R. Madison, J. McKee, M. McLaughlin, S. T. McWilliams, C. M. F. Mingarelli, D. J. Nice, S. Osłowski, T. T. Pennucci, B. B. P. Perera, D. Perrodin, A. Petiteau, A. Possenti, S. M. Ransom, D. Reardon, P. A. Rosado, S. A. Sanidas, A. Sesana, G. Shaifullah, X. Siemens, R. Smits, I. Stairs, B. Stappers, D. R. Stinebring, K. Stovall, J. Swiggum, S. R. Taylor, G. Theureau, C. Tiburzi, L. Toomey, M. Vallisneri, W. van Straten, A. Vecchio, J.-B. Wang, Y. Wang, X. P. You, W. W. Zhu, and X.-J. Zhu From spin noise to systematics: stochastic processes in the first International Pulsar Timing Array data release MNRAS (May 11, 2016) Vol. 458 2161-2187 doi:10.1093/mnras/stw395 first published online February 19, 2016
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ID Code:67647
Deposited By: Ruth Sustaita
Deposited On:03 Jun 2016 18:11
Last Modified:03 Jun 2016 18:11

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