Author: "Stefan Oslowski" - Searchworks@Jio Institute Digital Library Search Results

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102 results on '"Stefan Oslowski"'

51. Studying the Solar system with the International Pulsar Timing Array

Author: R. S. Lynch, L. Toomey, Paul Demorest, J. K. Swiggum, X. Siemens, Gregory Desvignes, A. Possenti, T. J. W. Lazio, Gilles Theureau, D. R. Madison, Lucas Guillemot, Joseph Simon, Renée Spiewak, Kejia Lee, Alberto Sesana, Andrea N. Lommen, Gemma H. Janssen, Ramesh Karuppusamy, Xing-Jiang Zhu, Ismaël Cognard, Chiara M. F. Mingarelli, Benjamin Stappers, Stefan Oslowski, Sean T. McWilliams, Scott M. Ransom, S. A. Sanidas, David J. Nice, Kang Liu, G. Shaifullah, Marjorie Gonzalez, Y J Guo, Caterina Tiburzi, Robert D. Ferdman, James M. Cordes, P. Lazarus, N. D. R. Bhat, Jonathan R. Gair, Daniel R. Stinebring, George Hobbs, Sarah Burke-Spolaor, Nipuni Palliyaguru, Benetge Perera, Daniel J. Reardon, Richard N. Manchester, Shi Dai, Michael Kramer, Ryan Shannon, A. Brazier, R. van Haasteren, Joris P. W. Verbiest, Zaven Arzoumanian, M. Burgay, Timothy T. Pennucci, W. van Straten, Lina Levin, K. Plant, Ingrid H. Stairs, Peter A. Gentile, Duncan R. Lorimer, E. Graikou, Weiwei Zhu, N. Garver-Daniels, D. J. Champion, Matthew Bailes, S. J. Chamberlin, Delphine Perrodin, Sourav Chatterjee, Kevin Stovall, Michael Keith, Matthew Kerr, Timothy Dolch, J. B. Wang, R. N. Caballero, C. G. Bassa, Emmanuel Fonseca, Michael T. Lam, Stephen Taylor, Paul D. Lasky, J. W. McKee, Maura McLaughlin, Laboratoire de physique et chimie de l'environnement (LPCE), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire Univers et Théories (LUTH (UMR_8102)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Caballero, R, Guo, Y, Lee, K, Lazarus, P, Champion, D, Desvignes, G, Kramer, M, Plant, K, Arzoumanian, Z, Bailes, M, Bassa, C, Bhat, N, Brazier, A, Burgay, M, Burke-Spolaor, S, Chamberlin, S, Chatterjee, S, Cognard, I, Cordes, J, Dai, S, Demorest, P, Dolch, T, Ferdman, R, Fonseca, E, Gair, J, Garver-Daniels, N, Gentile, P, Gonzalez, M, Graikou, E, Guillemot, L, Hobbs, G, Janssen, G, Karuppusamy, R, Keith, M, Kerr, M, Lam, M, Lasky, P, Lazio, T, Levin, L, Liu, K, Lommen, A, Lorimer, D, Lynch, R, Madison, D, Manchester, R, Mckee, J, Mclaughlin, M, Mcwilliams, S, Mingarelli, C, Nice, D, Osłowski, S, Palliyaguru, N, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Ransom, S, Reardon, D, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, van Haasteren, R, van Straten, W, Verbiest, J, Wang, J, Zhu, X, and Zhu, W
Subjects: Solar System, Dwarf planet, FOS: Physical sciences, Astrophysics, Ephemeris, 01 natural sciences, Jovian, Pulsar, pulsars: general, 0103 physical sciences, Sensitivity (control systems), ephemerides, 010303 astronomy & astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), methods: statistical, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astronomy and Astrophysics, Planetary system, Ephemeride, methods: data analysis, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Methods: data analysi, Reference frame, Astrophysics - Earth and Planetary Astrophysics
Abstract: Pulsar-timing analyses are sensitive to errors in the solar-system ephemerides (SSEs) that timing models utilise to estimate the location of the solar-system barycentre, the quasi-inertial reference frame to which all recorded pulse times-of-arrival are referred. Any error in the SSE will affect all pulsars, therefore pulsar timing arrays (PTAs) are a suitable tool to search for such errors and impose independent constraints on relevant physical parameters. We employ the first data release of the International Pulsar Timing Array to constrain the masses of the planet-moons systems and to search for possible unmodelled objects (UMOs) in the solar system. We employ ten SSEs from two independent research groups, derive and compare mass constraints of planetary systems, and derive the first PTA mass constraints on asteroid-belt objects. Constraints on planetary-system masses have been improved by factors of up to 20 from the previous relevant study using the same assumptions, with the mass of the Jovian system measured at 9.5479189(3)$\times10^{-4}$ $M_{\odot}$. The mass of the dwarf planet Ceres is measured at 4.7(4)$\times10^{-10}$ $M_{\odot}$. We also present the first sensitivity curves using real data that place generic limits on the masses of UMOs, which can also be used as upper limits on the mass of putative exotic objects. For example, upper limits on dark-matter clumps are comparable to published limits using independent methods. While the constraints on planetary masses derived with all employed SSEs are consistent, we note and discuss differences in the associated timing residuals and UMO sensitivity curves., Comment: Accepted for publication by the Monthly Notices of the Royal Astronomical Society
Published: 2018

52. European Pulsar Timing Array limits on an isotropic stochastic gravitational-wave background

Author: Pablo Rosado, Chiara M. F. Mingarelli, Lucas Guillemot, Rutger van Haasteren, S. Sanidas, P. Brem, A. Lassus, M. B. Purver, Stanislav Babak, Cees Bassa, Jason W. T. Hessels, R. Smits, Antoine Petiteau, Alberto Vecchio, Ramesh Karuppusamy, D. J. Champion, Ismaël Cognard, Kejia Lee, Caterina Tiburzi, Andrea Possenti, Marta Burgay, P. Lazarus, Alberto Sesana, Lindley Lentati, Stefan Oslowski, Gemma H. Janssen, Stephen Taylor, Gregory Desvignes, Gilles Theureau, Joris P. W. Verbiest, Ben Stappers, Michael Kramer, R. Nicolas Caballero, Kuo Liu, Delphine Perrodin, Jonathan R. Gair, Cavendish Laboratory, University of Cambridge [UK] (CAM), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Birmingham City University (BCU), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Max-Planck-Institut für Radioastronomie (MPIFR), Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Netherlands Institute for Radio Astronomy (ASTRON), University of Amsterdam [Amsterdam] (UvA), Columbia Astrophysics Laboratory (CAL), Columbia University [New York], AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universität Bielefeld, Centre for Astrophysics and Supercomputing, Swinburne University of Technology [Melbourne], Netherlands Institute for Radio Astronomy ( ASTRON ), 'Programme National de Cosmologie and Galaxies' (PNCG) of CNRS/INSU, France, European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), European Project: 610058,EC:FP7:ERC,ERC-2013-SyG,BLACKHOLECAM(2014), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Lentati, L, Taylor, S, Mingarelli, C, Sesana, A, Sanidas, S, Vecchio, A, Caballero, R, Lee, K, van Haasteren, R, Babak, S, Bassa, C, Brem, P, Burgay, M, Champion, D, Cognard, I, Desvignes, G, Gair, J, Guillemot, L, Hessels, J, Janssen, G, Karuppusamy, R, Kramer, M, Lassus, A, Lazarus, P, Liu, K, Oslowski, S, Perrodin, D, Petiteau, A, Possenti, A, Purver, M, Rosado, P, Smits, R, Stappers, B, Theureau, G, Tiburzi, C, Verbiest, J, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), High Energy Astrophys. & Astropart. Phys (API, FNWI), and API (FNWI)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Cosmic microwave background, Cosmic background radiation, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Gravitational wave background, Pulsar timing array, gravitational waves methods: data analysis pulsars: general, Pulsar, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, Spectral index, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Gravitational wave, Spectral density, Astronomy and Astrophysics, Pulsars: general, Space and Planetary Science, astro-ph.CO, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, Methods: data analysi, astro-ph.IM
Abstract: We present new limits on an isotropic stochastic gravitational-wave background (GWB) using a six pulsar dataset spanning 18 yr of observations from the 2015 European Pulsar Timing Array data release. Performing a Bayesian analysis, we fit simultaneously for the intrinsic noise parameters for each pulsar, along with common correlated signals including clock, and Solar System ephemeris errors, obtaining a robust 95$\%$ upper limit on the dimensionless strain amplitude $A$ of the background of $A, 24 pages, 5 tables, 17 figures
Published: 2015

53. European Pulsar Timing Array limits on continuous gravitational waves from individual supermassive slack hole binaries

Author: Alberto Vecchio, S. Sanidas, Jonathan R. Gair, R. van Haasteren, L. Lentati, P. Lazarus, A. Possenti, R. N. Caballero, C. G. Bassa, Antoine Petiteau, S. Babak, Gregory Desvignes, Stephen Taylor, Gilles Theureau, R. Smits, Jason W. T. Hessels, Pablo Rosado, Michael Kramer, A. Lassus, D. J. Champion, Chiara M. F. Mingarelli, Benjamin Stappers, Gemma H. Janssen, Alberto Sesana, M. B. Purver, Lucas Guillemot, P. Brem, M. Burgay, Caterina Tiburzi, Stefan Oslowski, Kejia Lee, Joris P. W. Verbiest, Delphine Perrodin, Ramesh Karuppusamy, Ismaël Cognard, Kang Liu, Babak, S, Petiteau, A, Sesana, A, Brem, P, Rosado, P, Taylor, S, Lassus, A, Hessels, J, Bassa, C, Burgay, M, Caballero, R, Champion, D, Cognard, I, Desvignes, G, Gair, J, Guillemot, L, Janssen, G, Karuppusamy, R, Kramer, M, Lazarus, P, Lee, K, Lentati, L, Liu, K, Mingarelli, C, Oslowski, S, Perrodin, D, Possenti, A, Purver, M, Sanidas, S, Smits, R, Stappers, B, Theureau, G, Tiburzi, C, van Haasteren, R, Vecchio, A, Verbiest, J, Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, APC - Gravitation (APC-Gravitation), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Netherlands Institute for Radio Astronomy (ASTRON), INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Max-Planck-Institut für Radioastronomie (MPIFR), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], Cavendish Laboratory, Netherlands Institute for Radio Astronomy ( ASTRON ), Laboratoire Univers et Théories (LUTH (UMR_8102)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), NASA-California Institute of Technology (CALTECH), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, High Energy Astrophys. & Astropart. Phys (API, FNWI), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Institute of Astronomy, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), astro-ph.GA, gr-qc, Population, black hole physics, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, General Relativity and Quantum Cosmology, Pulsar timing array, Black hole physic, Pulsar, 0103 physical sciences, education, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, education.field_of_study, Supermassive black hole, 010308 nuclear & particles physics, Gravitational wave, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, European Pulsar Timing Array, Pulsars: general, Amplitude, gravitational waves, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.CO, Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), Astrophysics - Cosmology and Nongalactic Astrophysics, astro-ph.IM
Abstract: We have searched for continuous gravitational wave (CGW) signals produced by individually resolvable, circular supermassive black hole binaries (SMBHBs) in the latest EPTA dataset, which consists of ultra-precise timing data on 41 millisecond pulsars. We develop frequentist and Bayesian detection algorithms to search both for monochromatic and frequency-evolving systems. None of the adopted algorithms show evidence for the presence of such a CGW signal, indicating that the data are best described by pulsar and radiometer noise only. Depending on the adopted detection algorithm, the 95\% upper limit on the sky-averaged strain amplitude lies in the range $6\times 10^{-15}10^9$M$_\odot$ out to a distance of about 25Mpc, and with $\cal{M}_c>10^{10}$M$_\odot$ out to a distance of about 1Gpc ($z\approx0.2$). We show that state-of-the-art SMBHB population models predict $, Comment: 16 pages, 11 figures, accepted for publication in MNRAS
Published: 2015

54. X-rays from the mode-switching PSR B0943+10

Author: M. Serylak, Sandro Mereghetti, Michela Rigoselli, G. A. E. Wright, Kevin Stovall, Jason W. T. Hessels, Andrea Tiengo, Paolo Esposito, Roberto Turolla, Stefan Oslowski, J. M. Griessmeier, W. Hermsen, Dipanjan Mitra, Andrea Possenti, Ben Stappers, Joanna M. Rankin, A. Horneffer, Lucien Kuiper, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Mereghetti, S, Kuiper, L, Tiengo, A, Hessels, J, Hermsen, W, Stovall, K, Possenti, A, Rankin, J, Esposito, P, Turolla, R, Mitra, D, Wright, G, Stappers, B, Horneffer, A, Oslowski, S, Serylak, M, Griessmeier, J, Rigoselli, M, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Mode (statistics), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, Astrophysics, Thermal emission, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Radio telescope, stars: neutron, Pulsar, Space and Planetary Science, pulsars: general, 0103 physical sciences, X-rays: individual (PSR B0943+10), Spectral analysis, Astrophysics - High Energy Astrophysical Phenomena, Polar cap, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences
Abstract: New simultaneous X-ray and radio observations of the archetypal mode-switching pulsar PSR B0943+10 have been carried out with XMM-Newton and the LOFAR, LWA and Arecibo radio telescopes in November 2014. They allowed us to better constrain the X-ray spectral and variability properties of this pulsar and to detect, for the first time, the X-ray pulsations also during the X-ray-fainter mode. The combined timing and spectral analysis indicates that unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap are present during both radio modes and vary in a correlated way., Comment: 4 pages, 1 figure, 1 table - To appear in the proceedings of "IAUS 337: Pulsar Astrophysics - The Next 50 Years" eds: P. Weltevrede, B.B.P. Perera, L. Levin Preston & S. Sanidas
Published: 2017

55. Limits on the Mass, Velocity and Orbit of PSR J1933$-$6211

Author: F. Jankowski, Michael Kramer, Stefan Oslowski, E. Graikou, D. J. Champion, Joris P. W. Verbiest, and Thomas M. Tauris
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, 01 natural sciences, Orbital inclination, Radio telescope, Pulsar, Millisecond pulsar, pulsars: general, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Scintillation, 010308 nuclear & particles physics, Astronomy, Static timing analysis, White dwarf, Astronomy and Astrophysics, Neutron star, pulsars: individual: PSR J1933-6211, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present a high-precision timing analysis of PSR J1933$-$6211, a millisecond pulsar (MSP) with a 3.5-ms spin period and a white dwarf (WD) companion, using data from the Parkes radio telescope. Since we have accurately measured the polarization properties of this pulsar we have applied the matrix template matching approach in which the times of arrival are measured using full polarimetric information. We achieved a weighted root-mean-square timing residuals (rms) of the timing residuals of 1.23 $\rm \mu s$, 15.5$\%$ improvement compared to the total intensity timing analysis. After studying the scintillation properties of this pulsar we put constraints on the inclination angle of the system. Based on these measurements and on $\chi^2$ mapping we put a 2-$\sigma$ upper limit on the companion mass (0.44 M$_\odot$). Since this mass limit cannot reveal the nature of the companion we further investigate the possibility of the companion to be a He WD. Applying the orbital period-mass relation for such WDs, we conclude that the mass of a He WD companion would be about 0.26$\pm$0.01 M$_\odot$ which, combined with the measured mass function and orbital inclination limits, would lead to a light pulsar mass $\leqslant$ 1.0 M$_\odot$. This result seems unlikely based on current neutron star formation models and we therefore conclude that PSR J1933$-$6211 most likely has a CO WD companion, which allows for a solution with a more massive pulsar.
Published: 2017

56. Wide-band profile domain pulsar timing analysis

Author: Stefan Oslowski, Pablo Rosado, R. N. Manchester, Sarah Burke-Spolaor, Yuri Levin, Shi Dai, Michael P. Hobson, Paul D. Lasky, L. Lentati, Xing-Jiang Zhu, W. van Straten, N. D. Ramesh Bhat, Renée Spiewak, James Dempsey, Daniel J. Reardon, Linqing Wen, Ryan Shannon, L. Toomey, Vikram Ravi, Matthew Bailes, J. B. Wang, George Hobbs, Matthew Kerr, William A. Coles, and X. P. You
Subjects: FOS: Physical sciences, Astronomy & Astrophysics, 01 natural sciences, general [pulsars], Hybrid Monte Carlo, Pulsar, pulsars: general, 0103 physical sciences, individual [pulsars], Range (statistics), data analysis [methods], 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Gravitational wave, Static timing analysis, Astronomy and Astrophysics, methods: data analysis, Pulse (physics), Computational physics, pulsars: individual, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Piecewise, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Parametrization, Astronomical and Space Sciences
Abstract: We extend profile domain pulsar timing to incorporate wide-band effects such as frequency-dependent profile evolution and broadband shape variation in the pulse profile. We also incorporate models for temporal variations in both pulse width and in the separation in phase of the main pulse and interpulse. We perform the analysis with both nested sampling and Hamiltonian Monte Carlo methods. In the latter case we introduce a new parameterisation of the posterior that is extremely efficient in the low signal-to-noise regime and can be readily applied to a wide range of scientific problems. We apply this methodology to a series of simulations, and to between seven and nine yr of observations for PSRs J1713$+$0747, J1744$-$1134, and J1909$-$3744 with frequency coverage that spans 700-3600MHz. We use a smooth model for profile evolution across the full frequency range, and compare smooth and piecewise models for the temporal variations in DM. We find the profile domain framework consistently results in improved timing precision compared to the standard analysis paradigm by as much as 40% for timing parameters. Incorporating smoothness in the DM variations into the model further improves timing precision by as much as 30%. For PSR J1713+0747 we also detect pulse shape variation uncorrelated between epochs, which we attribute to variation intrinsic to the pulsar at a level consistent with previously published analyses. Not accounting for this shape variation biases the measured arrival times at the level of $\sim$30ns, the same order of magnitude as the expected shift due to gravitational-waves in the pulsar timing band., 22 pages, submitted to MNRAS
Published: 2017

57. Comparison of Pulsar Positions from Timing and Very Long Baseline Astrometry

Author: Yuri Levin, Matthew Kerr, Stefan Oslowski, William A. Coles, Xing-Jiang Zhu, James Dempsey, Vikram Ravi, X. P. You, J. P. Yuan, Na Wang, Paul D. Lasky, Matthew Bailes, George Hobbs, Michael Keith, Christopher J. Russell, Linqing Wen, Ryan Shannon, W. van Straten, Pablo Rosado, N. D. R. Bhat, Shi Dai, Daniel J. Reardon, Richard N. Manchester, Renée Spiewak, J. B. Wang, and Lawrence Toomey
Subjects: astro-ph.GA, FOS: Physical sciences, Ephemeris, 01 natural sciences, Radio telescope, Pulsar, Axial tilt, 0103 physical sciences, Very-long-baseline interferometry, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Earth and Planetary Astrophysics (astro-ph.EP), Physics, astro-ph.HE, 010308 nuclear & particles physics, Astronomy, Astronomy and Astrophysics, Quasar, Astrometry, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.EP, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Reference frame, Astrophysics - Earth and Planetary Astrophysics, astro-ph.IM
Abstract: Pulsar positions can be measured with high precision using both pulsar timing methods and very-long-baseline interferometry (VLBI). Pulsar timing positions are referenced to a solar-system ephemeris, whereas VLBI positions are referenced to distant quasars. Here we compare pulsar positions from published VLBI measurements with those obtained from pulsar timing data from the Nanshan and Parkes radio telescopes in order to relate the two reference frames. We find that the timing positions differ significantly from the VLBI positions (and also differ between different ephemerides). A statistically significant change in the obliquity of the ecliptic of $2.16\pm0.33$\,mas is found for the JPL ephemeris DE405, but no significant rotation is found in subsequent JPL ephemerides. The accuracy with which we can relate the two frames is limited by the current uncertainties in the VLBI reference source positions and in matching the pulsars to their reference source. Not only do the timing positions depend on the ephemeris used in computing them, but also different segments of the timing data lead to varying position estimates. These variations are mostly common to all ephemerides, but slight changes are seen at the 10$\mu$as level between ephemerides., Comment: accepted by MNRAS,22 pages, 5 figures
Published: 2017

58. The UTMOST: A Hybrid Digital Signal Processor Transforms the Molonglo Observatory Synthesis Telescope

Author: M. O'Neill, A. J. Green, Pablo Rosado, D. Campbell-Wilson, Matthew Bailes, Chris Flynn, Richard W. Hunstead, V. Venkatraman Krishnan, Andrew Jameson, F. Jankowski, Tara Murphy, John D. Bunton, Vikram Ravi, Aditya Parthasarathy, Bryan Gaensler, M. Caleb, Ewan Barr, D. Temby, Wael Farah, Evan Keane, Stefan Oslowski, T. Bateman, and Shivani Bhandari
Subjects: Physics, Digital signal processor, 010308 nuclear & particles physics, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Bandwidth (signal processing), Astrophysics::Instrumentation and Methods for Astrophysics, Electrical engineering, Astronomy and Astrophysics, 01 natural sciences, law.invention, Telescope, Radio telescope, Pulsar, Space and Planetary Science, law, 0103 physical sciences, Radio frequency, Molonglo Observatory Synthesis Telescope, business, 010303 astronomy & astrophysics, Radio astronomy
Abstract: The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m2 radio telescope located 40 km from Canberra, Australia. Its operating band (820–851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.
Published: 2017

59. Inferring the population properties of binary neutron stars with gravitational-wave measurements of spin

Author: Xing-Jiang Zhu, Yuri Levin, Eric Thrane, Stefan Oslowski, and Paul D. Lasky
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, Angular momentum, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Population, X-ray binary, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, General Relativity and Quantum Cosmology, Gravitation, Neutron star, Pulsar, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, education, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Spin-½
Abstract: The recent LIGO-Virgo detection of gravitational waves from a binary neutron star inspiral event GW170817 and the discovery of its accompanying electromagnetic signals mark a new era for multimessenger astronomy. In the coming years, advanced gravitational-wave detectors are likely to detect tens to hundreds of similar events. Neutron stars in binaries can possess significant spin, which is imprinted on the gravitational waveform via the effective spin parameter $\chi_\text{eff}$. We explore the astrophysical inferences made possible by gravitational-wave measurements of $\chi_\text{eff}$. First, using a fiducial model informed by radio observations, we estimate that $\approx15-30\%$ of binary neutron stars should have spins measurable at $\gtrsim 90\%$ confidence level by advanced detectors assuming the spin axis of the recycled neutron star aligns with the total orbital angular momentum of the binary. Second, using Bayesian inference, we show that it is possible to tell whether or not the spin axis of the recycled neutron star tends to be aligned with the binary orbit using $\gtrsim 30$ detections. Finally, interesting constraints can be placed on neutron star magnetic field decay after $\gtrsim 300$ detections, if the spin periods and magnetic field strengths of Galactic binary neutron stars are representative of the merging population., Comment: Accepted for publication in Phys. Rev. D; 14 pages, 8 figures, 4 tables
Published: 2017
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60. Searching for gravitational wave memory bursts with the Parkes Pulsar Timing Array

Author: Jing Wang, Sarah Burke-Spolaor, Matthew Bailes, W. van Straten, Stefan Oslowski, George Hobbs, Yuri Levin, Vikram Ravi, Na Wang, N. D. R. Bhat, L. Toomey, Shi Dai, Xing-Jiang Zhu, Richard N. Manchester, Linqing Wen, Ryan Shannon, Matthew Kerr, William A. Coles, Michael Keith, and D. R. Madison
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Gravitational-wave observatory, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, general [pulsars], Gravitational-wave astronomy, Binary pulsar, Pulsar timing array, Pulsar, pulsars: general, data analysis [methods], Instrumentation and Methods for Astrophysics (astro-ph.IM), media_common, Physics, Supermassive black hole, Gravitational wave, Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, methods: data analysis, gravitational waves, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), Astrophysics - Instrumentation and Methods for Astrophysics, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Anisotropic bursts of gravitational radiation produced by events such as super-massive black hole mergers leave permanent imprints on space. Such gravitational wave "memory" (GWM) signals are, in principle, detectable through pulsar timing as sudden changes in the apparent pulse frequency of a pulsar. If an array of pulsars is monitored as a GWM signal passes over the Earth, the pulsars would simultaneously appear to change pulse frequency by an amount that varies with their sky position in a quadrupolar fashion. Here we describe a search algorithm for such events and apply the algorithm to approximately six years of data from the Parkes Pulsar Timing Array. We find no GWM events and set an upper bound on the rate for events which could have been detected. We show, using simple models of black hole coalescence rates, that this non-detection is not unexpected., Accepted by MNRAS
Published: 2014

61. Erratum: Population synthesis of double neutron stars

Author: Tomasz Bulik, Krzysztof Belczynski, D. Gondek-Rosinska, and Stefan Oslowski
Subjects: Physics, Neutron star, Space and Planetary Science, Population synthesis, Astronomy and Astrophysics, Astrophysics
Published: 2019

62. THE DISTURBANCE OF A MILLISECOND PULSAR MAGNETOSPHERE

Author: Renée Spiewak, Yuri Levin, L. Toomey, Stefan Oslowski, Linqing Wen, Ryan Shannon, W. van Straten, Xing-Jiang Zhu, Daniel J. Reardon, Matthew Bailes, N. D. R. Bhat, Lindley Lentati, Shi Dai, Pablo Rosado, Michael Keith, James Dempsey, Paul D. Lasky, George Hobbs, Richard N. Manchester, Matthew Kerr, William A. Coles, Vikram Ravi, X. P. You, and J. B. Wang
Subjects: astro-ph.SR, Astrophysics::High Energy Astrophysical Phenomena, individual (PSR J1643-1224) [pulsars], Magnetosphere, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, Rotation, 01 natural sciences, general [pulsars], neutron [stars], Pulsar, Millisecond pulsar, 0103 physical sciences, individual [pulsars], Variation (astronomy), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Pulse (physics), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Noise (radio), Astronomical and Space Sciences
Abstract: Pulsar timing has enabled some of the strongest tests of fundamental physics. Central to the technique is the assumption that the detected radio pulses can be used to accurately measure the rotation of the pulsar. Here we report on a broad-band variation in the pulse profile of the millisecond pulsar J1643-1224. A new component of emission suddenly appears in the pulse profile, decays over 4 months, and results in a permanently modified pulse shape. Profile variations such as these may be the origin of timing noise observed in other millisecond pulsars. The sensitivity of pulsar-timing observations to gravitational radiation can be increased by accounting for this variability., Accepted to ApJ Letters
Published: 2016

63. A model for distortions of polarisation-angle curves in radio pulsars

Author: J. Dyks, M. Serylak, Stefan Oslowski, B. Rudak, Lucas Guillemot, L. Saha, Ismaël Cognard, Copernicus Astronomical Center of the Polish Academy of Sciences (CAMK), Polish Academy of Sciences (PAN), Department of Physics and Astronomy [South Africa], University of the Western Cape, Observatoire de Paris - Site de Paris (OP), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), and The Nancay Radio Observatory is operated by the Paris Observatory, associated with the French Centre National de la Recherche Scientifique (CNRS).This work was supported by the National Science Centre grant DEC-2011/02/A/ST9/00256
Subjects: [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, Phase (waves), FOS: Physical sciences, Astrophysics, Curvature, 01 natural sciences, Radio telescope, pulsars: individual: PSR B1821-24A, Pulsar, Millisecond pulsar, Distortion, pulsars: general, 0103 physical sciences, Emissivity, pulsars: individual: PSR J0437-4715, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astronomy and Astrophysics, Microbeam, radiation mechanisms: non-thermal, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Computational physics, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Some radio pulsar profiles (in particular those of millisecond pulsars contain wide emission structures which cover large intervals of pulse phase. Local distortions of an average curve of polarisation angle (PA) can be identified in such profiles, and they are often found to be associated with absorption features or narrow emission components. The features may be interpreted as a convolution of a lateral profile of an emitter with a microscopic radiation pattern of a non-negligible angular extent. We study a model which assumes that such an extended microbeam of the X-mode curvature radiation is spreading the radiation polarised at a fixed position angle within an interval of pulse phase. The model is capable of interpreting the strongly dissimilar polarisation of double notches in PSR B1821-24A (for which we present new polarisation data from the Nancay Radio Telescope) and PSR J0437-4715. It also explains a step-like change in PA observed at the bifurcated trailing component in the profile of J0437-4715. A generic form of the modelled PA distortion is a zigzag-shaped wiggle, which in the presence of the second polarisation mode (O mode) can be magnified or transformed into a W- or U-shaped deflection of a total net PA. The model's efficiency in interpreting dissimilar polarisation effects provides further credence to the stream-based (fan-beam) geometry of pulsar emission. It also suggests that the microbeam width may not always be assumed negligible in comparison with the angular scale of emissivity gradients in the emission region., Comment: 14 pages, 16 figures, accepted for publication in Astronomy and Astrophysics
Published: 2016

64. A LOFAR census of non-recycled pulsars: average profiles, dispersion measures, flux densities, and spectra

Author: Anna V. Bilous, Heino Falcke, Jochen Eislöffel, P. Zarka, Sera Markoff, Ben Stappers, Rene P. Breton, Aris Karastergiou, J. van Leeuwen, M. Serylak, S. Sanidas, V. M. Malofeev, Evan Keane, V. I. Kondratiev, J. W. Broderick, Stefan Oslowski, Michael Kramer, Antonia Rowlinson, S. ter Veen, Jean-Mathias Grießmeier, Joris P. W. Verbiest, Simon Cooper, Patrick Weltevrede, D. Michilli, Charlotte Sobey, Jason W. T. Hessels, Martin Bell, High Energy Astrophys. & Astropart. Phys (API, FNWI), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University [Nijmegen], Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Radioastronomie (MPIFR), Centre for Astrophysics and Supercomputing (Centre for Astrophysics and Supercomputing), Swinburne University of Technology [Melbourne], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Pushchino Radio Astronomy Observatory, School of Physics and Astronomy [Southampton], University of Southampton, Oxford Astrophysics, University of Oxford, Fakultät für Physik, Universität Bielefeld, Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Department of Physics and Astronomy [South Africa], University of the Western Cape (UWC), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Centre of Excellence for All-Sky Astrophysics (CAASTRO), Thüringer Landessternwarte Tautenburg (TLS), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Radboud university [Nijmegen], University of Oxford [Oxford], Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), and University of the Western Cape
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Spectral line, Pulsar, pulsars: general, 0103 physical sciences, Dispersion (optics), Range (statistics), 010303 astronomy & astrophysics, Hardware_REGISTER-TRANSFER-LEVELIMPLEMENTATION, Solar and Stellar Astrophysics (astro-ph.SR), ISM: general, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Spectral index, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astronomy and Astrophysics, telescopes, LOFAR, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Intensity (heat transfer)
Abstract: We present first results from a LOFAR census of non-recycled pulsars. The census includes almost all such pulsars known (194 sources) at declinations ${\rm Dec}> 8^\circ$ and Galactic latitudes $|{\rm Gb}| > 3^\circ$, regardless of their expected flux densities and scattering times. Each pulsar was observed for $\geq 20$ minutes in the contiguous frequency range of 110--188 MHz. Full-Stokes data were recorded. We present the dispersion measures, flux densities, and calibrated total intensity profiles for the 158 pulsars detected in the sample. The median uncertainty in census dispersion measures ($1.5 \times 10^{-3}$ pc cm$^{-3}$) is ten times smaller, on average, than in the ATNF pulsar catalogue. We combined census flux densities with those in the literature and fitted the resulting broadband spectra with single or broken power-law functions. For 48 census pulsars such fits are being published for the first time. Typically, the choice between single and broken power-laws, as well as the location of the spectral break, were highly influenced by the spectral coverage of the available flux density measurements. In particular, the inclusion of measurements below 100 MHz appears essential for investigating the low-frequency turnover in the spectra for most of the census pulsars. For several pulsars, we compared the spectral indices from different works and found the typical spread of values to be within 0.5--1.5, suggesting a prevailing underestimation of spectral index errors in the literature. The census observations yielded some unexpected individual source results, as we describe in the paper. Lastly, we will provide this unique sample of wide-band, low-frequency pulse profiles via the European Pulsar Network Database., 39 pages, 26 figures, accepted by A&A. Fixed a number of typos, rewritten DM variations section (conclusions unchanged). Arxiv pdf contains tables that will be published as electronic only by A&A
Published: 2016

65. A glitch in the millisecond pulsar J0613-0200

Author: Caterina Tiburzi, L. Lentati, G. Shaifullah, James Mckee, Andrew Lyne, Christine Jordan, R. N. Caballero, Ramesh Karuppusamy, Ismaël Cognard, Gemma H. Janssen, E. Graikou, D. J. Champion, Joris P. W. Verbiest, Benjamin Stappers, Stefan Oslowski, Michael Kramer, Delphine Perrodin, Gregory Desvignes, Axel Jessner, P. Lazarus, Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Jodrell Bank Centre for Astrophysics, Max-Planck-Institut für Radioastronomie (MPIFR), Cavendish Laboratory, University of Cambridge [UK] (CAM), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Universität Bielefeld, INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Region Centre in France, European Project: 279702,EC:FP7:ERC,ERC-2011-StG_20101014,BEACON(2011), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), ITA, GBR, FRA, DEU, NLD, Mckee, J, Janssen, G, Stappers, B, Lyne, A, Caballero, R, Lentati, L, Desvignes, G, Jessner, A, Jordan, C, Karuppusamy, R, Kramer, M, Cognard, I, Champion, D, Graikou, E, Lazarus, P, Osłowski, S, Perrodin, D, Shaifullah, G, Tiburzi, C, and Verbiest, J
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Pulsar planet, FOS: Physical sciences, Astrophysics, 01 natural sciences, Binary pulsar, law.invention, Telescope, stars: neutron, stars:rotation, Pulsar timing array, pulsars: individual: PSR J0613-0200, Pulsar, stars: rotation, law, Millisecond pulsar, pulsars: general, 0103 physical sciences, stars:neutron, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, pulsars:general, Astrophysics - Solar and Stellar Astrophysics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Glitch (astronomy), Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, pulsars:individual (PSR J0613 − 0200)
Abstract: We present evidence for a small glitch in the spin evolution of the millisecond pulsar J0613$-$0200, using the EPTA Data Release 1.0, combined with Jodrell Bank analogue filterbank TOAs recorded with the Lovell telescope and Effelsberg Pulsar Observing System TOAs. A spin frequency step of 0.82(3) nHz and frequency derivative step of ${-1.6(39) \times 10^{-19}\,\text{Hz} \ \text{s}^{-1}}$ are measured at the epoch of MJD 50888(30). After PSR B1821$-$24A, this is only the second glitch ever observed in a millisecond pulsar, with a fractional size in frequency of ${\Delta \nu/\nu=2.5(1) \times 10^{-12}}$, which is several times smaller than the previous smallest glitch. PSR J0613$-$0200 is used in gravitational wave searches with pulsar timing arrays, and is to date only the second such pulsar to have experienced a glitch in a combined 886 pulsar-years of observations. We find that accurately modelling the glitch does not impact the timing precision for pulsar timing array applications. We estimate that for the current set of millisecond pulsars included in the International Pulsar Timing Array, there is a probability of $\sim 50$% that another glitch will be observed in a timing array pulsar within 10 years., Comment: accepted for publication in MNRAS
Published: 2016

66. The noise properties of 42 millisecond pulsars from the European Pulsar Timing Array and their impact on gravitational-wave searches

Author: Chiara M. F. Mingarelli, Benjamin Stappers, Alberto Vecchio, S. Babak, Caterina Tiburzi, R. N. Caballero, Kang Liu, A. Lassus, Stefan Oslowski, C. G. Bassa, Delphine Perrodin, Lucas Guillemot, R. van Haasteren, Kejia Lee, P. Brem, E. Graikou, Jason W. T. Hessels, Joris P. W. Verbiest, Pablo Rosado, M. B. Purver, D. J. Champion, Gemma H. Janssen, Ramesh Karuppusamy, Ismaël Cognard, Jonathan R. Gair, G. Shaifullah, J. W. McKee, Stephen Taylor, Michael Kramer, Antoine Petiteau, R. Smits, Alberto Sesana, P. Lazarus, S. Sanidas, L. Lentati, M. Burgay, A. Possenti, Gregory Desvignes, Gilles Theureau, High Energy Astrophys. & Astropart. Phys (API, FNWI), Caballero, R, Lee, K, Lentati, L, Desvignes, G, Champion, D, Verbiest, J, Janssen, G, Stappers, B, Kramer, M, Lazarus, P, Possenti, A, Tiburzi, C, Perrodin, D, Osłowski, S, Babak, S, Bassa, C, Brem, P, Burgay, M, Cognard, I, Gair, J, Graikou, E, Guillemot, L, Hessels, J, Karuppusamy, R, Lassus, A, Liu, K, Mckee, J, Mingarelli, C, Petiteau, A, Purver, M, Rosado, P, Sanidas, S, Sesana, A, Shaifullah, G, Smits, R, Taylor, S, Theureau, G, van Haasteren, R, Vecchio, A, Max-Planck-Institut für Radioastronomie (MPIFR), Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], Cavendish Laboratory, University of Cambridge [UK] (CAM), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Universität Bielefeld, Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), School of Mathematics - University of Edinburgh, University of Edinburgh, Netherlands Institute for Radio Astronomy (ASTRON), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), APC - Gravitation (APC-Gravitation), AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Netherlands Institute for Radio Astronomy ( ASTRON ), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), School of Physics and Astronomy [Birmingham], University of Birmingham [Birmingham], Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), California Institute of Technology (CALTECH)-NASA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, 01 natural sciences, Binary pulsar, Pulsar, Millisecond pulsar, pulsars: general, 0103 physical sciences, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, gravitational waves – methods: data analysis – pulsars: general, Physics, Supermassive black hole, 010308 nuclear & particles physics, Gravitational wave, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, methods: data analysis, European Pulsar Timing Array, Amplitude, gravitational waves, 13. Climate action, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), Astrophysics - Cosmology and Nongalactic Astrophysics, Methods: data analysi
Abstract: The sensitivity of Pulsar Timing Arrays to gravitational waves depends on the noise present in the individual pulsar timing data. Noise may be either intrinsic or extrinsic to the pulsar. Intrinsic sources of noise will include rotational instabilities, for example. Extrinsic sources of noise include contributions from physical processes which are not sufficiently well modelled, for example, dispersion and scattering effects, analysis errors and instrumental instabilities. We present the results from a noise analysis for 42 millisecond pulsars (MSPs) observed with the European Pulsar Timing Array. For characterising the low-frequency, stochastic and achromatic noise component, or "timing noise", we employ two methods, based on Bayesian and frequentist statistics. For 25 MSPs, we achieve statistically significant measurements of their timing noise parameters and find that the two methods give consistent results. For the remaining 17 MSPs, we place upper limits on the timing noise amplitude at the 95% confidence level. We additionally place an upper limit on the contribution to the pulsar noise budget from errors in the reference terrestrial time standards (below 1%), and we find evidence for a noise component which is present only in the data of one of the four used telescopes. Finally, we estimate that the timing noise of individual pulsars reduces the sensitivity of this data set to an isotropic, stochastic GW background by a factor of >9.1 and by a factor of >2.3 for continuous GWs from resolvable, inspiralling supermassive black-hole binaries with circular orbits., Accepted for publication by the Monthly Notices of the Royal Astronomical Society
Published: 2016

67. A millisecond pulsar in an extremely wide binary system

Author: Benjamin Stappers, R. Smits, Kejia Lee, Lucas Guillemot, E. Graikou, R. N. Caballero, C. G. Bassa, Gemma H. Janssen, P. Lazarus, Joris P. W. Verbiest, Weiwei Zhu, Thomas Wevers, Peter G. Jonker, Ramesh Karuppusamy, S. Sanidas, G. Shaifullah, Ismaël Cognard, Andrew Lyne, A. Jessner, J. W. McKee, Michael Kramer, Caterina Tiburzi, K. Lazaridis, Stefan Oslowski, Paulo C. C. Freire, D. J. Champion, Thomas M. Tauris, Kang Liu, Christine Jordan, Delphine Perrodin, L. Lentati, Gregory Desvignes, Gilles Theureau, Netherlands Institute for Radio Astronomy (ASTRON), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Max-Planck-Institut für Radioastronomie (MPIFR), Department of Astrophysics [Nijmegen], Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen]-Radboud university [Nijmegen], SRON Netherlands Institute for Space Research (SRON), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Fakultät für Physik, Universität Bielefeld, Universität Bielefeld, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Kavli Institute for Astronomy and Astrophysics [Beijing] (KIAA-PKU), Peking University [Beijing], INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Programme National de Cosmologie and Galaxies' (PNCG) of CNRS/INSU, France., European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), European Project: 610058,EC:FP7:ERC,ERC-2013-SyG,BLACKHOLECAM(2014), ITA, GBR, FRA, DEU, TWN, NLD, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Bassa, C, Janssen, G, Stappers, B, Tauris, T, Wevers, T, Jonker, P, Lentati, L, Verbiest, J, Desvignes, G, Graikou, E, Guillemot, L, Freire, P, Lazarus, P, Caballero, R, Champion, D, Cognard, I, Jessner, A, Jordan, C, Karuppusamy, R, Kramer, M, Lazaridis, K, Lee, K, Liu, K, Lyne, A, Mckee, J, Osłowski, S, Perrodin, D, Sanidas, S, Shaifullah, G, Smits, R, Theureau, G, Tiburzi, C, Zhu, W, Radboud University [Nijmegen]-Radboud University [Nijmegen], Universität Bielefeld = Bielefeld University, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: stars: individual: PSR J1024-0719, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Pulsar planet, Supernovae: general, FOS: Physical sciences, Astrophysics, 01 natural sciences, Binary pulsar, stars: neutron, Pulsar, Millisecond pulsar, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], supernovae: general, Astronomy and Astrophysics, European Pulsar Timing Array, Neutron star, binaries: general, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Sub-Earth, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, X-ray pulsar
Abstract: We report on 22 yrs of radio timing observations of the millisecond pulsar J1024$-$0719 by the telescopes participating in the European Pulsar Timing Array (EPTA). These observations reveal a significant second derivative of the pulsar spin frequency and confirm the discrepancy between the parallax and Shklovskii distances that has been reported earlier. We also present optical astrometry, photometry and spectroscopy of 2MASS J10243869$-$0719190. We find that it is a low-metallicity main-sequence star (K7V spectral type, $\mathrm{[M/H]}=-1.0$, $T_\mathrm{eff}=4050\pm50$ K) and that its position, proper motion and distance are consistent with those of PSR J1024$-$0719. We conclude that PSR J1024$-$0719 and 2MASS J10243869$-$0719190 form a common proper motion pair and are gravitationally bound. The gravitational interaction between the main-sequence star and the pulsar accounts for the spin frequency derivatives, which in turn resolves the distance discrepancy. Our observations suggest that the pulsar and main-sequence star are in an extremely wide ($P_\mathrm{b}>200$ yr) orbit. Combining the radial velocity of the companion and proper motion of the pulsar, we find that the binary system has a high spatial velocity of $384\pm45$ km s$^{-1}$ with respect to the local standard of rest and has a Galactic orbit consistent with halo objects. Since the observed main-sequence companion star cannot have recycled the pulsar to millisecond spin periods, an exotic formation scenario is required. We demonstrate that this extremely wide-orbit binary could have evolved from a triple system that underwent an asymmetric supernova explosion, though find that significant fine-tuning during the explosion is required. Finally, we discuss the implications of the long period orbit on the timing stability of PSR J1024$-$0719 in light of its inclusion in pulsar timing arrays., 16 pages, 12 figures, 2 tables, submitted for publication in MNRAS
Published: 2016

68. Gravitational-Wave Cosmology across 29 Decades in Frequency

Author: Renée Spiewak, Willem van Straten, John T. Giblin, James Dempsey, X. P. You, Vikram Ravi, Pablo Rosado, Linqing Wen, Ryan Shannon, Jingbo Wang, Matthew Bailes, Yuri Levin, Xing-Jiang Zhu, Eric Thrane, Chiara M. F. Mingarelli, Matthew Kerr, Robert R. Caldwell, George Hobbs, Tristan L. Smith, Stefan Oslowski, Richard N. Manchester, Daniel J. Reardon, L. Toomey, N. D. Ramesh Bhat, Sarah Burke-Spolaor, Paul D. Lasky, and Shi Dai
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), QC1-999, Cosmic microwave background, FOS: Physical sciences, General Physics and Astronomy, General Relativity and Quantum Cosmology (gr-qc), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, General Relativity and Quantum Cosmology, Cosmology, symbols.namesake, Big Bang nucleosynthesis, 0103 physical sciences, Planck, 010306 general physics, Physics, Spectral index, 010308 nuclear & particles physics, Gravitational wave, LIGO, symbols, Baryon acoustic oscillations, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Quantum fluctuations of the gravitational field in the early Universe, amplified by inflation, produce a primordial gravitational-wave background across a broad frequency band. We derive constraints on the spectrum of this gravitational radiation, and hence on theories of the early Universe, by combining experiments that cover 29 orders of magnitude in frequency. These include Planck observations of cosmic microwave background temperature and polarization power spectra and lensing, together with baryon acoustic oscillations and big bang nucleosynthesis measurements, as well as new pulsar timing array and ground-based interferometer limits. While individual experiments constrain the gravitational-wave energy density in specific frequency bands, the combination of experiments allows us to constrain cosmological parameters, including the inflationary spectral index, $n_t$, and the tensor-to-scalar ratio, $r$. Results from individual experiments include the most stringent nanohertz limit of the primordial background to date from the Parkes Pulsar Timing Array, $��_{\rm gw}(f), accepted for publication in Physical Review X
Published: 2016

69. Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR

Author: J. van Leeuwen, Matthias Steinmetz, T. E. Hassall, A. Nelles, E. de Geus, M. Pilia, B. W. Stappers, Heino Falcke, H. J. A. Röttgering, Annalisa Bonafede, Oleg Smirnov, Anna V. Bilous, Satyendra Thoudam, Evan Keane, Peter G. Jonker, W. Frieswijk, Rudy Wijnands, A. Noutsos, M. Pietka, John D. Swinbank, Richard Fallows, R. J. van Weeren, M. Pandey-Pommier, Olaf Wucknitz, A. Alexov, Rebecca McFadden, E. Juette, F. Breitling, Stefan J. Wijnholds, Aris Karastergiou, Benedetta Ciardi, H. Paas, Antonia Rowlinson, Dominik J. Schwarz, Michael Kramer, A. I. F. Stewart, Y. Tang, Ashish Asgekar, K. Zagkouris, James A. Anderson, Chiara Ferrari, S. Duscha, James Miller-Jones, Andrew Lyne, Stefan Oslowski, Adam T. Deller, A. de Jong, R. C. Vermeulen, Gianni Bernardi, I. M. Avruch, M. A. Garrett, M. C. Toribio, Jochen Eislöffel, Charlotte Sobey, A. J. van der Horst, Rene P. Breton, Cyril Tasse, Marcus Brüggen, J. W. Broderick, Gerard H. Kuper, S. ter Veen, A. W. Gunst, Rob Fender, P. Zarka, D. McKay-Bukowski, Martin Bell, A. Horneffer, M. Kuniyoshi, Patrick Weltevrede, M. Serylak, A. G. Polatidis, Ralph A. M. J. Wijers, Mark J. Bentum, Christian Vocks, Jean-Mathias Grießmeier, Sera Markoff, Jason W. T. Hessels, Stephane Corbel, Laura Birzan, J. P. Hamaker, Wolfgang Reich, Michel Tagger, P. Maat, V. I. Kondratiev, George Heald, Gottfried Mann, R. Pizzo, Astronomy, Netherlands Institute for Radio Astronomy (ASTRON), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Vrije Universiteit Medical Centre (VUMC), Vrije Universiteit Amsterdam [Amsterdam] (VU), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Oxford Astrophysics, University of Oxford, School of Physics and Astronomy [Southampton], University of Southampton, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University [Nijmegen], Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Centre for Astrophysics and Supercomputing [Swinburne] (CAS), Swinburne University of Technology [Melbourne], Department of Physics [Oxford], Max-Planck-Institut für Radioastronomie (MPIFR), Universität Bielefeld = Bielefeld University, University of Cape Town, Space Telescope Science Institute (STSci), Epidémiologie et Biostatistique [Bordeaux], Université Bordeaux Segalen - Bordeaux 2-Institut de Santé Publique, d'Épidémiologie et de Développement (ISPED)-Institut National de la Santé et de la Recherche Médicale (INSERM), SRON Netherlands Institute for Space Research (SRON), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], University of Hamburg, Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ), University of Edinburgh, Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Structural Dynamics and Acoustics, University of Twente, Thüringer Landessternwarte Tautenburg (TLS), Institute of Mathematical and Physical Sciences, Department of Astrophysics [Oxford], Département de Géologie, Université de Montréal (UdeM), Astronomisches Institut der Ruhr-Universität Bochum, Ruhr-Universität Bochum [Bochum], Leibniz-Institut für Astrophysik Potsdam (AIP), Department of Physical Sciences, University of Oulu, University of Oulu, Curtin University [Perth], Planning and Transport Research Centre (PATREC), University of Groningen [Groningen], Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Australia Telescope National Facility (ATNF), Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Institute of Farm Animal Genetics (ING), Friedrich-Loeffler-Institut (FLI), SKA South Africa, Ska South Africa, Astrophysikalisches Institut Potsdam (AIP), Department of Physics [Dunedin], University of Otago [Dunedin, Nouvelle-Zélande], Princeton University, Edinburgh Research Station, Centre for Ecology and Hydrology, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Astrophysics [Nijmegen], Radboud University [Nijmegen]-Radboud University [Nijmegen], Anton Pannekoek Institute for Astronomy, Argelander-Institut für Astronomie (AlfA), Rheinische Friedrich-Wilhelms-Universität Bonn, Alexander von Humboldt Foundation Agence Nationale de la Recherche ANR-09-JCJC-0001-01, ANR-09-JCJC-0001,OPALES(2009), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), European Project: 617199,EC:FP7:ERC,ERC-2013-CoG,ALERT(2014), European Project: 224838,EC:FP7:PEOPLE,FP7-PEOPLE-2007-4-3-IRG,PULSARS WITH LOFAR(2008), ROUCHON, Nathalie, Jeunes chercheuses et jeunes chercheurs - - OPALES2009 - ANR-09-JCJC-0001 - JCJC - VALID, DRAGNET: A high-speed, wide-angle camera for catching extreme astrophysical events - DRAGNET - - EC:FP7:ERC2014-01-01 - 2018-12-31 - 337062 - VALID, ALERT - The Apertif-LOFAR Exploration of the Radio Transient Sky - ALERT - - EC:FP7:ERC2014-12-01 - 2019-11-30 - 617199 - VALID, Radio pulsars with LOFAR: a study of extreme physics laboratories. - PULSARS WITH LOFAR - - EC:FP7:PEOPLE2008-05-01 - 2012-04-30 - 224838 - VALID, High Energy Astrophys. & Astropart. Phys (API, FNWI), University of Oxford [Oxford], Radboud university [Nijmegen], Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Fakultät für Physik, Universität Bielefeld, Universität Bielefeld, University of the Western Cape, Cape Town, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), University of Twente [Netherlands], Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Radboud university [Nijmegen]-Radboud university [Nijmegen], Harvard University-Smithsonian Institution, Universiteit Leiden, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Pilia, M., Hessels, J.W.T., Stappers, B.W., Kondratiev, V.I., Kramer, M., Van Leeuwen, J., Weltevrede, P., Lyne, A.G., Zagkouris, K., Hassall, T.E., Bilous, A.V., Breton, R.P., Falcke, H., Grießmeier, J.-M., Keane, E., Karastergiou, A., Kuniyoshi, M., Noutsos, A., Osłowski, S., Serylak, M., Sobey, C., Ter Veen, S., Alexov, A., Anderson, J., Asgekar, A., Avruch, I.M., Bell, M.E., Bentum, M.J., Bernardi, G., Bîrzan, L., Bonafede, A., Breitling, F., Broderick, J.W., Brüggen, M., Ciardi, B., Corbel, S., De Geus, E., De Jong, A., Deller, A., Duscha, S., Eislöffel, J., Fallows, R.A., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., Gunst, A.W., Hamaker, J.P., Heald, G., Horneffer, A., Jonker, P., Juette, E., Kuper, G., Maat, P., Mann, G., Markoff, S., McFadden, R., McKay-Bukowski, D., Miller-Jones, J.C.A., Nelles, A., Paas, H., Pandey-Pommier, M., Pietka, M., Pizzo, R., Polatidis, A.G., Reich, W., Röttgering, H., Rowlinson, A., Schwarz, D., Smirnov, O., Steinmetz, M., Stewart, A., Swinbank, J.D., Tagger, M., Tang, Y., Tasse, C., Thoudam, S., Toribio, M.C., Van Der Horst, A.J., Vermeulen, R., Vocks, C., Van Weeren, R.J., Wijers, R.A.M.J., Wijnands, R., Wijnholds, S.J., Wucknitz, O., and Zarka, P.
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, METIS-321663, Astrophysics::Cosmology and Extragalactic Astrophysics, Low frequency, 01 natural sciences, Radio spectrum, law.invention, Telescope, Radio telescope, [SDU] Sciences of the Universe [physics], stars: neutron, Pulsar, law, pulsars: general, 0103 physical sciences, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), IR-103184, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, LOFAR, Astronomy and Astrophysic, Astrophysics - Astrophysics of Galaxies, Interstellar medium, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Radio frequency, EWI-27451, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: LOFAR offers the unique capability of observing pulsars across the 10-240 MHz frequency range with a fractional bandwidth of roughly 50%. This spectral range is well-suited for studying the frequency evolution of pulse profile morphology caused by both intrinsic and extrinsic effects: such as changing emission altitude in the pulsar magnetosphere or scatter broadening by the interstellar medium, respectively. The magnitude of most of these effects increases rapidly towards low frequencies. LOFAR can thus address a number of open questions about the nature of radio pulsar emission and its propagation through the interstellar medium. We present the average pulse profiles of 100 pulsars observed in the two LOFAR frequency bands: High Band (120-167 MHz, 100 profiles) and Low Band (15-62 MHz, 26 profiles). We compare them with Westerbork Synthesis Radio Telescope (WSRT) and Lovell Telescope observations at higher frequencies (350 and1400 MHz) in order to study the profile evolution. The profiles are aligned in absolute phase by folding with a new set of timing solutions from the Lovell Telescope, which we present along with precise dispersion measures obtained with LOFAR. We find that the profile evolution with decreasing radio frequency does not follow a specific trend but, depending on the geometry of the pulsar, new components can enter into, or be hidden from, view. Nonetheless, in general our observations confirm the widening of pulsar profiles at low frequencies, as expected from radius-to-frequency mapping or birefringence theories. We offer this catalog of low-frequency pulsar profiles in a user friendly way via the EPN Database of Pulsar Profiles (http://www.epta.eu.org/epndb/)., Comment: 38 pages, 11 figures, 5 tables, A&A in press, updated with editorial corrections
Published: 2016

70. Versatile directional searches for gravitational waves with pulsar timing arrays

Author: Pablo Rosado, Sarah Burke-Spolaor, Paul D. Lasky, Yuri Levin, Dustin R. Madison, James Dempsey, Matthew Bailes, Xing-Jiang Zhu, Stefan Oslowski, X. P. You, Daniel J. Reardon, Matthew Kerr, J. B. Wang, William A. Coles, L. Toomey, Linqing Wen, Ryan Shannon, Michael Keith, Vikram Ravi, Richard N. Manchester, George Hobbs, W. van Straten, Caterina Tiburzi, N. D. R. Bhat, Shi Dai, and Renée Spiewak
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Pulsar timing array, Pulsar, Millisecond pulsar, pulsars: general, 0103 physical sciences, Circular orbit, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Galaxy cluster, Physics, Supermassive black hole, 010308 nuclear & particles physics, Gravitational wave, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Polarization (waves), methods: data analysis, gravitational waves, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, astro-ph.IM
Abstract: By regularly monitoring the most stable millisecond pulsars over many years, pulsar timing arrays (PTAs) are positioned to detect and study correlations in the timing behaviour of those pulsars. Gravitational waves (GWs) from supermassive black hole binaries (SMBHBs) are an exciting potentially detectable source of such correlations. We describe a straight-forward technique by which a PTA can be "phased-up" to form time series of the two polarisation modes of GWs coming from a particular direction of the sky. Our technique requires no assumptions regarding the time-domain behaviour of a GW signal. This method has already been used to place stringent bounds on GWs from individual SMBHBs in circular orbits. Here, we describe the methodology and demonstrate the versatility of the technique in searches for a wide variety of GW signals including bursts with unmodeled waveforms. Using the first six years of data from the Parkes Pulsar Timing Array, we conduct an all-sky search for a detectable excess of GW power from any direction. For the lines of sight to several nearby massive galaxy clusters, we carry out a more detailed search for GW bursts with memory, which are distinct signatures of SMBHB mergers. In all cases, we find that the data are consistent with noise., Accepted for publication by MNRAS
Published: 2016

71. A LOFAR census of millisecond pulsars

Author: Jochen Eislöffel, Aris Karastergiou, Patrick Weltevrede, Simon Cooper, Rudy Wijnands, Sera Markoff, Joris P. W. Verbiest, Rene P. Breton, S. ter Veen, J. W. Broderick, J. van Leeuwen, Jason W. T. Hessels, Charlotte Sobey, Stephane Corbel, V. I. Kondratiev, Heino Falcke, Stefan Oslowski, Antonia Rowlinson, Ralph A. M. J. Wijers, Jean-Mattias Grießmeier, M. Kuniyoshi, John D. Swinbank, T. E. Hassall, Evan Keane, M. Pilia, Anna V. Bilous, Martin Bell, B. W. Stappers, A. Noutsos, A. Alexov, Michael Kramer, P. Zarka, Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Radioastronomie (MPIFR), University of Amsterdam [Amsterdam] (UvA), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Centre for Astrophysics and Supercomputing [Swinburne] (CAS), Swinburne University of Technology [Melbourne], Universität Bielefeld, Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Oxford Astrophysics, University of Oxford [Oxford], CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), University of Southampton, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Thüringer Landessternwarte Tautenburg (TLS), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), ANR-11-IDEX-0005-02/10-LABX-0023,UnivEarthS,Earth - Planets - Universe: observation, modeling, transfer(2011), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Jodrell Bank Centre for Astrophysics (JBCA), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0005,USPC,Université Sorbonne Paris Cité(2011), Radboud University [Nijmegen], Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), University of Oxford, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), and API (FNWI)
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, stars: neutron, Pulsar timing array, symbols.namesake, Telescopes – Radio continuum: stars – Stars: neutron – pulsa rs: general, Pulsar, Millisecond pulsar, pulsars: general, 0103 physical sciences, Dispersion (optics), Faraday effect, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Gravitational wave, telescopes, Astronomy and Astrophysics, LOFAR, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, symbols, Radio frequency, Astrophysics - High Energy Astrophysical Phenomena, radio continuum: stars
Abstract: We report the detection of 48 millisecond pulsars (MSPs) out of 75 observed thus far using the LOFAR in the frequency range 110-188 MHz. We have also detected three MSPs out of nine observed in the frequency range 38-77 MHz. This is the largest sample of MSPs ever observed at these low frequencies, and half of the detected MSPs were observed for the first time at frequencies below 200 MHz. We present the average pulse profiles of the detected MSPs, their effective pulse widths, and flux densities and compare these with higher observing frequencies. The flux-calibrated, multifrequency LOFAR pulse profiles are publicly available via the EPN Database of Pulsar Profiles. We also present average values of dispersion measures (DM) and discuss DM and profile variations. About 35% of the MSPs show strong narrow profiles, another 25% exhibit scattered profiles, and the rest are only weakly detected. A qualitative comparison of LOFAR profiles with those at higher radio frequencies shows constant separation between profile components. Similarly, the profile widths are consistent with those observed at higher frequencies, unless scattering dominates at the lowest frequencies. This is very different from what is observed for normal pulsars and suggests a compact emission region in the MSP magnetosphere. The amplitude ratio of the profile components, on the other hand, can dramatically change towards low frequencies, often with the trailing component becoming dominant. As previously demonstrated this can be caused by aberration and retardation. This data set enables high-precision studies of pulse profile evolution with frequency, dispersion, Faraday rotation, and scattering in the interstellar medium. Characterising and correcting these systematic effects may improve pulsar-timing precision at higher observing frequencies, where pulsar timing array projects aim to directly detect gravitational waves., 27 pages, 10 figures, 5 tables, accepted to A&A
Published: 2016

72. 21 year timing of the black-widow pulsar J2051-0827

Author: Caterina Tiburzi, E. Graikou, Gemma H. Janssen, Norbert Wex, A. Possenti, Christine Jordan, Ben Stappers, Andrew Lyne, R. N. Caballero, Stefan Oslowski, Lucas Guillemot, Michael Kramer, Gregory Desvignes, K. Lazaridis, C. G. Bassa, Axel Jessner, G. Shaifullah, D. J. Champion, P. Lazarus, J. W. McKee, Ramesh Karuppusamy, Ismaël Cognard, Joris P. W. Verbiest, Delphine Perrodin, Thomas M. Tauris, Paulo C. C. Freire, Shaifullah, G, Verbiest, J, Freire, P, Tauris, T, Wex, N, Osłowski, S, Stappers, B, Bassa, C, Caballero, R, Champion, D, Cognard, I, Desvignes, G, Graikou, E, Guillemot, L, Janssen, G, Jessner, A, Jordan, C, Karuppusamy, R, Kramer, M, Lazaridis, K, Lazarus, P, Lyne, A, Mckee, J, Perrodin, D, Possenti, A, Tiburzi, C, Max-Planck-Institut für Radioastronomie (MPIFR), Universität Bielefeld, Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Proper motion, general pulsars individual, individual: PSR J2051-0827, Pulsar planet, Binaries: eclipsing, FOS: Physical sciences, fundamental properties pulsars, Astrophysics, 01 natural sciences, Binary pulsar, Radio telescope, Pulsars: individual: PSR J2051-0827, Pulsar, Millisecond pulsar, Binaries: close, 0103 physical sciences, pulsars, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, binaries:close stars, PSR J2051−0827, European Pulsar Timing Array, Pulsars: general, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), binaries:eclipsing, Astrophysics - High Energy Astrophysical Phenomena, X-ray pulsar
Abstract: Timing results for the black-widow pulsar J2051-0827 are presented, using a 21-year dataset from four European Pulsar Timing Array telescopes and the Parkes radio telescope. This dataset, which is the longest published to date for a black-widow system, allows for an improved analysis that addresses previously unknown biases. While secular variations, as identified in previous analyses, are recovered, short-term variations are detected for the first time. Concurrently, a significant decrease of approx. 2.5x10-3 cm-3 pc in the dispersion measure associated with PSR J2051-0827 is measured for the first time and improvements are also made to estimates of the proper motion. Finally, PSR J2051-0827 is shown to have entered a relatively stable state suggesting the possibility of its eventual inclusion in pulsar timing arrays., Accepted for publication by MNRAS, 10 pages, 6 figures
Published: 2016

73. A deep campaign to characterize the synchronous radio/X-ray mode switching of PSR B0943+10

Author: A. Horneffer, W. Hermsen, M. Serylak, R. Turolla, Dipanjan Mitra, Sandro Mereghetti, L. Kuiper, Stefan Oslowski, Kevin Stovall, Jason W. T. Hessels, Joanna M. Rankin, Paolo Esposito, Andrea Tiengo, Ben Stappers, Jean-Mathias Griessmeier, A. Possenti, G. Wright, INAF-IASF Milano, Istituto Nazionale di Astrofisica (INAF), SRON Netherlands Institute for Space Research (SRON), Center for Advanced Numerical Simulations, Istituto Universitario di Studi Superiori di Pavia (CESNA-IUSS), Istituto Universitario di Studi Superiori (IUSS), Netherlands Institute for Radio Astronomy (ASTRON), Department of Physics and Astronomy [Albuquerque], The University of New Mexico [Albuquerque], Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), University of Vermont [Burlington], Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita degli Studi di Padova, School of Physics and Astronomy [Manchester], University of Manchester [Manchester], Jodrell Bank Centre for Astrophysics, Max-Planck-Institut für Radioastronomie (MPIFR), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Physics and Astronomy [South Africa], University of the Western Cape, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Padova = University of Padua (Unipd), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), University of the Western Cape (UWC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)
Subjects: Photon, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Power law, Radio telescope, stars: neutron, Pulsar, pulsars: general, 0103 physical sciences, X-rays: individual (PSR B0943+10), Black-body radiation, 010306 general physics, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, LOFAR, Space and Planetary Science, Magnetic field, 13. Climate action, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on simultaneous X-ray and radio observations of the mode-switching pulsar PSR B0943+10 obtained with the XMM-Newton satellite and the LOFAR, LWA and Arecibo radio telescopes in November 2014. We confirm the synchronous X-ray/radio switching between a radio-bright (B) and a radio-quiet (Q) mode, in which the X-ray flux is a factor ~2.4 higher than in the B-mode. We discovered X-ray pulsations, with pulsed fraction of 38+/-5% (0.5-2 keV), during the B-mode, and confirm their presence in Q-mode, where the pulsed fraction increases with energy from ~20% up to ~65% at 2 keV. We found marginal evidence for an increase in the X-ray pulsed fraction during B-mode on a timescale of hours. The Q-mode X-ray spectrum requires a fit with a two-component model (either a power-law plus blackbody or the sum of two blackbodies), while the B-mode spectrum is well fit by a single blackbody (a single power-law is rejected). With a maximum likelihood analysis, we found that in Q-mode the pulsed emission has a thermal blackbody spectrum with temperature ~3.4x10^6 K and the unpulsed emission is a power-law with photon index ~2.5, while during B-mode both the pulsed and unpulsed emission can be fit by either a blackbody or a power law with similar values of temperature and photon index. A Chandra image shows no evidence for diffuse X-ray emission. These results support a scenario in which both unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap (~1500 m^2) with a strong non-dipolar magnetic field (~10^{14} G), are present during both radio modes and vary in intensity in a correlated way. This is broadly consistent with the predictions of the partially screened gap model and does not necessarily imply global magnetospheric rearrangements to explain the mode switching., Comment: To be published on The Astrophysical Journal
Published: 2016

74. High signal-to-noise ratio observations and the ultimate limits of precision pulsar timing

Author: W. van Straten, Matthew Bailes, Paul Demorest, George Hobbs, and Stefan Oslowski
Subjects: Physics, Pulsar timing array, Pulsar, Space and Planetary Science, Millisecond pulsar, Astrophysics::High Energy Astrophysical Phenomena, Bandwidth (signal processing), Flux, Astronomy and Astrophysics, Impulse (physics), Residual, Standard deviation, Computational physics
Abstract: We demonstrate that the sensitivity of high-precision pulsar timing experiments will be ultimately limited by the broad-band intensity modulation that is intrinsic to the pulsar’s stochastic radio signal. That is, as the peak flux of the pulsar approaches that of the system equivalent flux density, neither greater antenna gain nor increased instrumental bandwidth will improve timing precision. These conclusions proceed from an analysis of the covariance matrix used to characterize residual pulse profile fluctuations following the template-matching procedure for arrival time estimation. We perform such an analysis on 25 h of high-precision timing observations of the closest and brightest millisecond pulsar, PSR J0437−4715. In these data, the standard deviation of the post-fit arrival time residuals is approximately four times greater than that predicted by considering the system equivalent flux density, mean pulsar flux and the effective width of the pulsed emission. We develop a technique based on principal component analysis to mitigate the effects of shape variations on arrival time estimation and demonstrate its validity using a number of illustrative simulations. When applied to our observations, the method reduces arrival time residual noise by approximately 20 per cent. We conclude that, owing primarily to the intrinsic variability of the radio emission from PSR J0437−4715 at 20 cm, timing precision in this observing band better than 30–40 ns in 1 h is highly unlikely, regardless of future improvements in antenna gain or instrumental bandwidth. We describe the intrinsic variability of the pulsar signal as stochastic wide-band impulse modulated self-noise (SWIMS) and argue that SWIMS will likely limit the timing precision of every millisecond pulsar currently observed by pulsar timing array projects as larger and more sensitive antennas are built in the coming decades.
Published: 2011

75. Rotation measure variations for 20 millisecond pulsars

Author: W. M. Yan, Sarah Burke-Spolaor, William A. Coles, D. R. B. Yardley, Jonathan Khoo, Willem van Straten, Matthew Bailes, John Sarkissian, Stefan Oslowski, David Champion, Richard N. Manchester, A. Chaudhary, Ramesh Bhat, John Reynolds, George Hobbs, Na Wang, and Aidan Hotan
Subjects: Physics, Electron density, Line-of-sight, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Position angle, International Reference Ionosphere, Pulsar timing array, symbols.namesake, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Millisecond pulsar, Faraday effect, symbols, Ionosphere, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: We report on variations in the mean position angle of the 20 millisecond pulsars being observed as part of the Parkes Pulsar Timing Array (PPTA) project. It is found that the observed variations are dominated by changes in the Faraday rotation occurring in the Earth's ionosphere. Two ionospheric models are used to correct for the ionospheric contribution and it is found that one based on the International Reference Ionosphere gave the best results. Little or no significant long-term variation in interstellar RM was found with limits typically about 0.1 rad m$^{-2}$ yr$^{-1}$ in absolute value. In a few cases, apparently significant RM variations over timescales of a few 100 days or more were seen. These are unlikely to be due to localised magnetised regions crossing the line of sight since the implied magnetic fields are too high. Most probably they are statistical fluctuations due to random spatial and temporal variations in the interstellar electron density and magnetic field along the line of sight., Accepted for publication in Astrophysics & Space Science
Published: 2011

76. On detection of the stochastic gravitational-wave background using the Parkes pulsar timing array

Author: Matthew Bailes, Fredrick A. Jenet, Aidan Hotan, John Reynolds, Richard N. Manchester, N. D. R. Bhat, George Hobbs, William A. Coles, Sarah Burke-Spolaor, W. van Straten, Stefan Oslowski, Joris P. W. Verbiest, David Champion, D. R. B. Yardley, and John Sarkissian
Subjects: Physics, Signal processing, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Gravitational wave background, Radio telescope, Pulsar timing array, Pulsar, Sampling (signal processing), Space and Planetary Science, 0103 physical sciences, Arecibo Observatory, 010303 astronomy & astrophysics, Spectral leakage
Abstract: We search for the signature of an isotropic stochastic gravitational-wave background in pulsar timing observations using a frequency-domain correlation technique. These observations, which span roughly 12 yr, were obtained with the 64-m Parkes radio telescope augmented by public domain observations from the Arecibo Observatory. A wide range of signal processing issues unique to pulsar timing and not previously presented in the literature are discussed. These include the effects of quadratic removal, irregular sampling, and variable errors which exacerbate the spectral leakage inherent in estimating the steep red spectrum of the gravitational-wave background. These observations are found to be consistent with the null hypothesis, that no gravitational-wave background is present, with 76 percent confidence. We show that the detection statistic is dominated by the contributions of only a few pulsars because of the inhomogeneity of this data set. The issues of detecting the signature of a gravitational-wave background with future observations are discussed.
Published: 2011

77. Polarization observations of 20 millisecond pulsars

Author: William A. Coles, Na Wang, George Hobbs, Aidan Hotan, Ramesh Bhat, David Champion, W. M. Yan, Matthew Bailes, Jonathan Khoo, D. R. B. Yardley, Richard N. Manchester, Sarah Burke-Spolaor, Joris P. W. Verbiest, Stefan Oslowski, Willem van Straten, John Reynolds, and John Sarkissian
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Magnetosphere, Astronomy and Astrophysics, Astrophysics, Polarization (waves), Rotation, Position angle, Pulsar timing array, Pulsar, Space and Planetary Science, Millisecond pulsar, Noise (radio)
Abstract: Polarization profiles are presented for 20 millisecond pulsars that are being observed as part of the Parkes Pulsar Timing Array project. The observations used the Parkes multibeam receiver with a central frequency of 1369 MHz and the Parkes digital filterbank pulsar signal-processing system PDFB2. Because of the large total observing time, the summed polarization profiles have very high signal/noise ratios and show many previously undetected profile features. Thirteen of the 20 pulsars show emission over more than half of the pulse period. Polarization variations across the profiles are complex and the observed position angle variations are generally not in accord with the rotating-vector model for pulsar polarization. Never-the-less, the polarization properties are broadly similar to those of normal (non-millisecond) pulsars, suggesting that the basic radio emission mechanism is the same in both classes of pulsar. The results support the idea that radio emission from millisecond pulsars originates high in the pulsar magnetosphere, probably close to the emission regions for high-energy X-ray and gamma-ray emission. Rotation measures were obtained for all 20 pulsars, eight of which had no previously published measurements.
Published: 2011

78. Population synthesis of double neutron stars

Author: Stefan Oslowski, D. Gondek-Rosinska, Tomasz Bulik, and Krzysztof Belczynski
Subjects: Physics, education.field_of_study, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Population, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galaxy, LIGO, Accretion (astrophysics), Neutron star, Gravitational potential, Pulsar, Space and Planetary Science, education, Astrophysics::Galaxy Astrophysics
Abstract: Using the StarTrack binary population synthesis code we model the population of double neutron stars in the Galaxy. We include a detailed treatment of the spin evolution of each pulsar due to processes such as spin-down and spin-up during accretion events as well as magnetic field decay. We also model the spatial distribution of double neutron stars by including their natal kicks and subsequent propagation in the Galactic gravitational potential. This synthetic pulsar population is compared to the observed sample of double neutron stars taking into account the selection effects of detection in the radio band, to determine the most likely evolutionary parameters. With these parameters we determine the properties of the double neutron star binaries detectable in gravitational waves by the high frequency interferometers LIGO and VIRGO. In particular, we discuss the distributions of chirp masses and mass ratios in samples selected by their radio or gravitational wave emission.
Published: 2011

79. X-ray properties of the mode-switching pulsar PSR B0943+10

Author: Benjamin Stappers, A. Horneffer, Stefan Oslowski, Dipanjan Mitra, A. Possenti, Kevin Stovall, Jason W. T. Hessels, Roberto Turolla, Sandro Mereghetti, Michela Rigoselli, Joanna M. Rankin, W. Hermsen, M. Serylak, J. M. Griessmeier, Andrea Tiengo, Paolo Esposito, G. A. E. Wright, L. Kuiper, INAF - Osservatorio Astronomico di Milano (OAM), Istituto Nazionale di Astrofisica (INAF), SRON Netherlands Institute for Space Research (SRON), Scuola Universitaria Superiore Sant'Anna [Pisa] (SSSUP), Istituto Nazionale di Fisica Nucleare, Sezione di Pavia (INFN), Istituto Nazionale di Fisica Nucleare (INFN), Netherlands Institute for Radio Astronomy (ASTRON), Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), The University of New Mexico [Albuquerque], INAF - Osservatorio Astronomico di Cagliari (OAC), University of Vermont [Burlington], Universita degli Studi di Padova, National Centre for Radio Astrophysics [Pune] (NCRA), Tata Institute for Fundamental Research (TIFR), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Max-Planck-Institut für Radioastronomie (MPIFR), University of the Western Cape, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Mereghetti, S, Kuiper, L, Tiengo, A, Hessels, J, Hermsen, W, Stovall, K, Possenti, A, Rankin, J, Esposito, P, Turolla, R, Mitra, D, Wright, G, Stappers, B, Horneffer, A, Oslowski, S, Serylak, M, Griessmeier, J, Rigoselli, M, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: History, Astrophysics::High Energy Astrophysical Phenomena, Flux, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Physics and Astronomy(all), 01 natural sciences, Radio spectrum, Education, Radio telescope, stars: neutron, Pulsar, pulsars: general, 0103 physical sciences, X-rays: star, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, X-ray, LOFAR, Computer Science Applications, Magnetic field, pulsars: individual: PSR B0943+10, Astrophysics - High Energy Astrophysical Phenomena, Intensity (heat transfer)
Abstract: The mode-switching pulsar PSR B0943+10 has been extensively studied in the radio band for many years and, more recently, it has been found to vary also in X-rays, with a flux anticorrelated with the radio emission. Here we review the results of long observations of PSR B0943+10 carried out with XMM-Newton and the LOFAR, LWA and Arecibo radio telescopes in 2014. These results support a scenario in which both unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap (~1500 m2) with a strong non-dipolar magnetic field (~ 1014 G), are present during both radio modes and vary in intensity in a correlated way.
Published: 2017

80. Properties of double neutron stars

Author: Tomasz Bulik, Krzysztof Belczynski, D. Gondek-Rosinska, and Stefan Oslowski
Subjects: Physics, Equation of state, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, General Engineering, Phase (waves), Astronomy, Binary number, Astronomy and Astrophysics, Observable, Astrophysics, Nuclear matter, Neutron star, Space and Planetary Science, Population synthesis
Abstract: We summarize our studies on properties of double neutron stars observable in gravitational waves and in the radio. Binary population synthesis is used to calculate expected masses of neutron stars in binary systems taking into account the selection efects specific to each method of detection. We discuss recent relativistic results on final phase of inspiral of neutron star binaries showing how we can impose constraints on the equation of state of dense nuclear matter with gravitational wave observations.
Published: 2008

81. Timing analysis for 20 millisecond pulsars in the Parkes Pulsar Timing Array

Author: X. P. You, Matthew Kerr, William A. Coles, Vikram Ravi, Yuri Levin, Michael Keith, Paul D. Lasky, Xing-Jiang Zhu, Matthew Bailes, George Hobbs, Jiali Wang, Linqing Wen, Ryan Shannon, W. van Straten, L. Toomey, Stefan Oslowski, Sarah Burke-Spolaor, Richard N. Manchester, N. D. R. Bhat, Shi Dai, and Daniel J. Reardon
Subjects: FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, general [pulsars], 01 natural sciences, Pulsar timing array, Pulsar, proper motions, Millisecond pulsar, pulsars: general, 0103 physical sciences, ephemerides, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, Orbital elements, High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, 010308 nuclear & particles physics, Astronomy, Static timing analysis, Astronomy and Astrophysics, Astrometry, Shapiro delay, Space and Planetary Science, parallaxes, astrometry, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Astronomical and Space Sciences, Noise (radio), astro-ph.IM
Abstract: We present timing models for 20 millisecond pulsars in the Parkes Pulsar Timing Array. The precision of the parameter measurements in these models has been improved over earlier results by using longer data sets and modelling the non-stationary noise. We describe a new noise modelling procedure and demonstrate its effectiveness using simulated data. Our methodology includes the addition of annual dispersion measure (DM) variations to the timing models of some pulsars. We present the first significant parallax measurements for PSRs J1024-0719, J1045-4509, J1600-3053, J1603-7202, and J1730-2304, as well as the first significant measurements of some post-Keplerian orbital parameters in six binary pulsars, caused by kinematic effects. Improved Shapiro delay measurements have resulted in much improved pulsar mass measurements, particularly for PSRs J0437-4715 and J1909-3744 with $M_p=1.44\pm0.07$ $M_\odot$ and $M_p=1.47\pm0.03$ $M_\odot$ respectively. The improved orbital period-derivative measurement for PSR J0437-4715 results in a derived distance measurement at the 0.16% level of precision, $D=156.79\pm0.25$ pc, one of the most fractionally precise distance measurements of any star to date., Comment: 21 pages, 5 figures, 7 tables. Accepted for publication in MNRAS
Published: 2015

82. Gravitational waves from binary supermassive black holes missing in pulsar observations

Author: Stefan Oslowski, Daniel J. Reardon, Richard N. Manchester, Vikram Ravi, Yuri Levin, Xing-Jiang Zhu, Paul D. Lasky, W. van Straten, Michael Keith, Linqing Wen, J. S. B. Wyithe, Ryan Shannon, Matthew Kerr, William A. Coles, Matthew Bailes, N. D. R. Bhat, Shi Dai, George Hobbs, Jingbo Wang, Lindley Lentati, Sarah Burke-Spolaor, and L. Toomey
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Supermassive black hole, Multidisciplinary, Cosmology and Nongalactic Astrophysics (astro-ph.CO), General Science & Technology, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Binary number, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy merger, General Relativity and Quantum Cosmology, Radio telescope, Amplitude, Pulsar, Millisecond pulsar, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems will modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrain the characteristic amplitude of this background, $A_{\rm c,yr}$, to be < $1.0\times10^{-15}$ with 95% confidence. This limit excludes predicted ranges for $A_{\rm c,yr}$ from current models with 91-99.7% probability. We conclude that binary evolution is either stalled or dramatically accelerated by galactic-center environments, and that higher-cadence and shorter-wavelength observations would result in an increased sensitivity to gravitational waves., Published in Science 25 September 2015
Published: 2015

83. Limits on Fast Radio Bursts at 145 MHz with ARTEMIS, a real-time software backend

Author: Ben Stappers, Stefano Salvini, Fred Dulwich, Anna V. Bilous, A. Noutsos, Charlotte Sobey, Stephen J. Roberts, Wes Armour, J. van Leeuwen, V. I. Kondratiev, Michael Kramer, Aris Karastergiou, Stefan Oslowski, Jason W. T. Hessels, C. Williams, M. Serylak, A. Doo, Heino Falcke, Alessio Magro, Patrick Weltevrede, Ben Mort, Jayanth Chennamangalam, Evan Keane, Rene P. Breton, Jean-Mathias Grießmeier, Rhodes University, Grahamstown, Oxford Astrophysics, University of Oxford [Oxford], Evolution et Diversité Biologique (EDB), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), STFC Chilbolton Observatory, Science and Technology Facilities Council (STFC), Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], University of Amsterdam [Amsterdam] (UvA), Centre for Astrophysics and Supercomputing [Swinburne] (CAS), Swinburne University of Technology [Melbourne], Netherlands Institute for Radio Astronomy (ASTRON), Max-Planck-Institut für Radioastronomie (MPIFR), Columbia Astrophysics Laboratory (CAL), Columbia University [New York], University of Oxford, Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Radboud University [Nijmegen], and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Astronomy, media_common.quotation_subject, FOS: Physical sciences, Astrophysics, Low frequency, 01 natural sciences, Spectral line, Radio telescope, Pulsar, pulsars: general, 0103 physical sciences, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Canadian Hydrogen Intensity Mapping Experiment, Cosmic distance ladder, Astronomy and Astrophysics, LOFAR, instrumentation: miscellaneous, Space and Planetary Science, Sky, [SDU]Sciences of the Universe [physics], Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Fast Radio Bursts (FRBs), are millisecond radio signals that exhibit dispersion larger than what the Galactic electron density can account for. We have conducted a 1446 hour survey for Fast Radio Bursts (FRBs) at 145~MHz, covering a total of 4193 sq. deg on the sky. We used the UK station of the LOFAR radio telescope -- the Rawlings Array -- , accompanied for a majority of the time by the LOFAR station at Nan\c{c}ay, observing the same fields at the same frequency. Our real-time search backend, ARTEMIS, utilizes graphics processing units to search for pulses with dispersion measures up to 320 cm$^{-3}$ pc. Previous derived FRB rates from surveys around 1.4~GHz, and favoured FRB interpretations, motivated this survey, despite all previous detections occurring at higher dispersion measures. We detected no new FRBs above a signal-to-noise threshold of 10, leading to the most stringent upper limit yet on the FRB event rate at these frequencies: 29 sky$^{-1}$ day$^{-1}$ for 5~ms-duration pulses above 62~Jy. The non-detection could be due to scatter-broadening, limitations on the volume and time searched, or the shape of FRB flux density spectra. Assuming the latter and that FRBs are standard candles, the non-detection is compatible with the published FRB sky rate, if their spectra follow a power law with frequency ($\propto \nu^{\alpha}$), with $\alpha\gtrsim+0.1$, demonstrating a marked difference from pulsar spectra. Our results suggest that surveys at higher frequencies, including the low frequency component of the Square Kilometre Array, will have better chances to detect, estimate rates and understand the origin and properties of FRBs., Comment: Accepted for publication in MNRAS
Published: 2015

84. Limits on anisotropy in the nanohertz stochastic gravitational-wave background

Author: Kang Liu, Chiara M. F. Mingarelli, P. Lazarus, R. van Haasteren, R. N. Caballero, Joris P. W. Verbiest, Stefan Oslowski, C. G. Bassa, S. Babak, A. Lassus, Gregory Desvignes, Gilles Theureau, J. R. Gair, Alberto Vecchio, Delphine Perrodin, S. Sanidas, R. Smits, M. Burgay, Caterina Tiburzi, Gemma H. Janssen, L. Lentati, Alberto Sesana, Pablo Rosado, Ramesh Karuppusamy, A. Possenti, Ismaël Cognard, Jason W. T. Hessels, Antoine Petiteau, Stephen Taylor, D. J. Champion, Lucas Guillemot, P. Brem, Ben Stappers, Michael Kramer, M. B. Purver, University of Cambridge [UK] (CAM), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Cavendish Laboratory, Birmingham City University (BCU), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Jodrell Bank Centre for Astrophysics, University of Manchester [Manchester], INAF - Osservatorio Astronomico di Cagliari (OAC), Istituto Nazionale di Astrofisica (INAF), Max-Planck-Institut für Radioastronomie (MPIFR), Netherlands Institute for Radio Astronomy (ASTRON), University of Amsterdam [Amsterdam] (UvA), Columbia Astrophysics Laboratory (CAL), Columbia University [New York], Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Technische Fakultät, Universität Bielefeld, Universität Bielefeld = Bielefeld University, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre for Astrophysics and Supercomputing (Centre for Astrophysics and Supercomputing), Swinburne University of Technology [Melbourne], Max Planck Institute for Gravitational Physics (Albert Einstein Institute) (AEI), Programme National de Cosmologie and Galaxies' (PNCG) of CNRS/INSU, France, European Project: 610058,EC:FP7:ERC,ERC-2013-SyG,BLACKHOLECAM(2014), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), High Energy Astrophys. & Astropart. Phys (API, FNWI), API (FNWI), Taylor, S, Mingarelli, C, Gair, J, Sesana, A, Theureau, G, Babak, S, Bassa, C, Brem, P, Burgay, M, Caballero, R, Champion, D, Cognard, I, Desvignes, G, Guillemot, L, Hessels, J, Janssen, G, Karuppusamy, R, Kramer, M, Lassus, A, Lazarus, P, Lentati, L, Liu, K, Oslowski, S, Perrodin, D, Petiteau, A, Possenti, A, Purver, M, Rosado, P, Sanidas, S, Smits, R, Stappers, B, Tiburzi, C, Van Haasteren, R, Vecchio, A, and Verbiest, J
Subjects: Gravitational wave detectors and experiments, Cosmology and Nongalactic Astrophysics (astro-ph.CO), gr-qc, Population, gravitational waves, pulsar timing, cosmology, General Physics and Astronomy, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, General Relativity and Quantum Cosmology, Gravitational wave background, Pulsar, 0103 physical sciences, education, 010303 astronomy & astrophysics, Pulsars, astro-ph.HE, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), education.field_of_study, Supermassive black hole, Gravitational waves: theory, Galaxy mergers collisions and tidal interactions, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Gravitational wave, European Pulsar Timing Array, Amplitude, astro-ph.CO, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Astrophysics - High Energy Astrophysical Phenomena, Multipole expansion, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The paucity of observed supermassive black hole binaries (SMBHBs) may imply that the gravitational wave background (GWB) from this population is anisotropic, rendering existing analyses sub-optimal. We present the first constraints on the angular distribution of a nanohertz stochastic GWB from circular, inspiral-driven SMBHBs using the $2015$ European Pulsar Timing Array data [Desvignes et al. (in prep.)]. Our analysis of the GWB in the $\sim 2 - 90$ nHz band shows consistency with isotropy, with the strain amplitude in $l>0$ spherical harmonic multipoles $\lesssim 40\%$ of the monopole value. We expect that these more general techniques will become standard tools to probe the angular distribution of source populations., 6 pages, 2 figures, 1 table. Accepted for publication in Physical Review Letters
Published: 2015
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85. Pulsar Observations of Extreme Scattering Events

Author: W. van Straten, Matthew Bailes, Daniel J. Reardon, Yuri Levin, Stefan Oslowski, Xing-Jiang Zhu, Sarah Burke-Spolaor, George Hobbs, Linqing Wen, Richard N. Manchester, Ryan Shannon, N. D. R. Bhat, Shi Dai, X. P. You, Michael Keith, Matthew Kerr, William A. Coles, Jing Wang, Vikram Ravi, and L. Toomey
Subjects: Electron density, astro-ph.SR, ISM: structure, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, Physical Chemistry, general [pulsars], Atomic, Pulsar timing array, Particle and Plasma Physics, Pulsar, pulsars: general, Nuclear, Solar and Stellar Astrophysics (astro-ph.SR), astro-ph.HE, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Scintillation, Line-of-sight, Scattering, turbulence, Molecular, Astronomy and Astrophysics, Refraction, Interstellar medium, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, structure [ISM], Astrophysics - High Energy Astrophysical Phenomena, Astronomical and Space Sciences, Physical Chemistry (incl. Structural)
Abstract: Extreme scattering events (ESEs) in the interstellar medium (ISM) were first observed in regular flux measurements of compact extragalactic sources. They are characterized by a flux variation over a period of weeks, suggesting the passage of a "diverging plasma lens" across the line of sight. Modeling the refraction of such a lens indicates that the structure size must be of order AU and the electron density of order 10s of cm^{-3}. Similar structures have been observed in measurements of pulsar intensity scintillation and group delay. Here we report observations of two ESEs showing increases in both intensity scintillation and dispersion made with the Parkes Pulsar Timing Array (PPTA). These allow us to make more complete models of the ESE, including an estimate of the "outer-scale" of the turbulence in the plasma lens. These observations show clearly that the ESE structure is fully turbulent on an AU scale. They provide some support for the idea that the structures are extended along the line of sight, such as would be the case for a scattering shell. The dispersion measurements also show a variety of AU scale structures which would not be called ESEs, yet involve electron density variations typical of ESEs and likely have the same origin., Comment: Accepted by ApJ
Published: 2015
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86. Pulsar polarisation below 200 MHz: Average profiles and propagation effects

Author: Casey J. Law, M. Kuniyoshi, Tim D. Staley, M. Pietka, S. Cooper, Michael Kramer, Charlotte Sobey, Patrick Weltevrede, B. Scheers, S. Marko, P.G. Jonker, A. Alexov, P. Zarka, Heino Falcke, E. Rol, Aris Karastergiou, T. E. Hassall, Adam Stewart, Michael W. Wise, Rudy Wijnands, M. Pilia, James Miller-Jones, Martin Bell, Evan Keane, Jason W. T. Hessels, J. Masters, J.-M. Grießmeier, L. Bähren, Jochen Eislöffel, Antonia Rowlinson, T. Coenen, Hugh Garsden, Stefan Oslowski, J. van Leeuwen, B. W. Stappers, Rob Fender, Y. Cendes, K. Zagkouris, Anna V. Bilous, R. A. Osten, V. I. Kondratiev, John D. Swinbank, Ralph A. M. J. Wijers, Joris P. W. Verbiest, D. Carbone, S. ter Veen, A. J. van der Horst, M. Serylak, H. Spreeuw, Gijs Molenaar, Rene P. Breton, J. W. Broderick, Stephane Corbel, A. Noutsos, Kenneth C. Anderson, Netherlands Institute for Radio Astronomy (ASTRON), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], Max-Planck-Institut für Radioastronomie (MPIFR), Universität Bielefeld, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud university [Nijmegen], School of Mathematics [Cardiff], Cardiff University, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), School of Physics and Astronomy [Southampton], University of Southampton, Centre for Astrophysics and Supercomputing, Swinburne University of Technology [Melbourne], Sub-department of Astrophysics [Oxford], Department of Physics [Oxford], University of Oxford [Oxford]-University of Oxford [Oxford], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Thüringer Landessternwarte Tautenburg (TLS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Astrophysical Sciences [Princeton], Princeton University, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), European Project: 337062,EC:FP7:ERC,ERC-2013-StG,DRAGNET(2014), Database Architectures, Radboud University [Nijmegen], Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), University of Oxford-University of Oxford, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), High Energy Astrophys. & Astropart. Phys (API, FNWI), Jodrell Bank Centre for Astrophysics, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)
Subjects: Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Magnetosphere, Astrophysics, polarisation, low frequencies, Spectral line, symbols.namesake, Pulsar, Millisecond pulsar, pulsars: general, Faraday effect, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, instrumentation, polarization, Scattering, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], scattering, Astronomy and Astrophysics, LOFAR, radiation mechanisms: non-thermal, Astrophysics - Astrophysics of Galaxies, Interstellar medium, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, symbols, pulsars, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the highest-quality polarisation profiles to date of 16 non-recycled pulsars and four millisecond pulsars, observed below 200 MHz with the LOFAR high-band antennas. Based on the observed profiles, we perform an initial investigation of expected observational effects resulting from the propagation of polarised emission in the pulsar magnetosphere and the interstellar medium. The predictions of magnetospheric birefringence in pulsars have been tested using spectra of the pulse width and fractional polarisation from multifrequency data. The derived spectra offer only partial support for the expected effects of birefringence on the polarisation properties, with only about half of our sample being consistent with the model's predictions. It is noted that for some pulsars these measurements are contaminated by the effects of interstellar scattering. For a number of pulsars in our sample, we have observed significant variations in the amount of Faraday rotation as a function of pulse phase, which is possibly an artefact of scattering. These variations are typically two orders of magnitude smaller than that observed at 1400 MHz by Noutsos et al. (2009), for a different sample of southern pulsars. In this paper we present a possible explanation for the difference in magnitude of this effect between the two frequencies, based on scattering. Finally, we have estimated the magnetospheric emission heights of low-frequency radiation from four pulsars, based on the phase lags between the flux-density and the PA profiles, and the theoretical framework of Blaskiewicz, Cordes & Wasserman (1991). These estimates yielded heights of a few hundred km; at least for PSR B1133+16, this is consistent with emission heights derived based on radius-to-frequency mapping, but is up to a few times larger than the recent upper limit based on pulsar timing., 27 pages, 11 figures, 2 tables, A&A accepted
Published: 2015

87. Tracking dispersion measure variations of timing array pulsars with the GMRT

Author: Yashwant Gupta, Matthew Bailes, N. D. R. Bhat, Jayanta Roy, Michael Keith, Willem van Straten, Ujjwal Kumar, and Stefan Oslowski
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Giant Metrewave Radio Telescope, Epoch (astronomy), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Tracking (particle physics), Measure (mathematics), Pulsar timing array, Solar wind, Pulsar, Space and Planetary Science, Dispersion (optics), Astrophysics::Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract: We present the results from nearly three years of monitoring of the variations in dispersion measure (DM) along the line-of-sight to 11 millisecond pulsars using the Giant Metrewave Radio Telescope (GMRT). These results demonstrate accuracies of single epoch DM estimates of the order of 5x10^(-4) cm^(-3) pc. A preliminary comparison with the Parkes Pulsar Timing Array (PPTA) data shows that the measured DM fluctuations are comparable. We show effects of DM variations due to the solar wind and solar corona and compare with the existing models., Proceedings of IAUS 291 "Neutron Stars and Pulsars: Challenges and Opportunities after 80 years", J. van Leeuwen (ed.); 3 pages, 3 figures
Published: 2012

88. Limitations in timing precision due to single-pulse shape variability in millisecond pulsars

Author: Sarah Burke-Spolaor, L. Toomey, Yuri Levin, John Sarkissian, Stefan Oslowski, George Hobbs, Xing-Jiang Zhu, Matthew Kerr, William A. Coles, Vikram Ravi, N. D. R. Bhat, Linqing Wen, Ryan Shannon, Michael Keith, C. A. Raithel, Matthew Bailes, Richard N. Manchester, J. B. Wang, Shi Dai, and W. van Straten
Subjects: Mean squared error, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astronomy & Astrophysics, general [pulsars], Radio spectrum, stars: neutron, Pulsar timing array, neutron [stars], Pulsar, Millisecond pulsar, pulsars: general, data analysis [methods], Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Jitter, Physics, Gravitational wave, Bandwidth (signal processing), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, methods: data analysis, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, Astronomical and Space Sciences
Abstract: High-sensitivity radio-frequency observations of millisecond pulsars usually show stochastic, broadband, pulse-shape variations intrinsic to the pulsar emission process. These variations induce jitter noise in pulsar timing observations; understanding the properties of this noise is of particular importance for the effort to detect gravitational waves with pulsar timing arrays. We assess the short-term profile and timing stability of 22 millisecond pulsars that are part of the Parkes Pulsar Timing Array sample by examining intra-observation arrival time variability and single-pulse phenomenology. In 7 of the 22 pulsars, in the band centred at approximately 1400MHz, we find that the brightest observations are limited by intrinsic jitter. We find consistent results, either detections or upper limits, for jitter noise in other frequency bands. PSR J1909-3744 shows the lowest levels of jitter noise, which we estimate to contribute $\sim$10 ns root mean square error to the arrival times for hour-duration observations. Larger levels of jitter noise are found in pulsars with wider pulses and distributions of pulse intensities. The jitter noise in PSR J0437-4715 decorrelates over a bandwidth of $\sim$2 GHz. We show that the uncertainties associated with timing pulsar models can be improved by including physically motivated jitter uncertainties. Pulse-shape variations will limit the timing precision at future, more sensitive, telescopes; it is imperative to account for this noise when designing instrumentation and timing campaigns for these facilities., 21 pages, 23 figures, accepted by MNRAS
Published: 2014

89. Timing, polarimetry and physics of the bright, nearby millisecond pulsar PSR J0437-4715 - a single-pulse perspective

Author: Matthew Bailes, Andrew Jameson, George Hobbs, W. van Straten, and Stefan Oslowski
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), pulsars: individual (PSR J0437-4715), Astrophysics::High Energy Astrophysical Phenomena, Pulsar planet, Polarimetry, Single pulse, Magnetosphere, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Plasma, Polarization (waves), Pulsar, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Millisecond pulsar, pulsars: general, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Single pulses from radio pulsars contain a wealth of information about emission and propagation in the magnetosphere and insight into their timing properties. It was recently demonstrated that single-pulse emission is responsible for limiting the timing stability of the brightest of millisecond pulsars. We report on an analysis of more than a million single-pulses from PSR J0437-4715 and present various statistical properties such as the signal-to-noise ratio (S/N) distribution, timing and polarimetry of average profiles integrated from subpulses with chosen S/N cut-offs, modulation properties of the emission, phase-resolved statistics of the S/N, and two dimensional spherical histograms of the polarization vector orientation. The last of these indicates the presence of orthogonally polarised modes (OPMs). Combined with the dependence of the polarisation fraction on the S/N and polarimetry of the brightest pulses, the existence of OPMs constrains pulsar emission mechanisms and models for the plasma physics in the magnetosphere., Comment: MNRAS, in press. 14 pages, 14 figures. Please note that figures 12, 13 and 14 are low resolution versions due to arxiv's size restrictions. To obtain a full resolution version please see the journal version or contact the first author
Published: 2014
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90. The LOFAR pilot surveys for pulsars and fast radio transients

Author: K. Zagkouris, Stefan Oslowski, C. Schrijvers, Michel Tagger, A. Noutsos, Jean-Mathias Grießmeier, John D. Swinbank, Simon Cooper, Dominik J. Schwarz, Rob Fender, P. Zarka, Heino Falcke, Philip Best, V. I. Kondratiev, D. McKay-Bukowski, Charlotte Sobey, Arthur Corstanje, Gerard H. Kuper, Christian Vocks, T. Coenen, M. A. Garrett, Y. Tang, M. Serylak, T. E. Hassall, Oleg Smirnov, Gottfried Mann, Olaf Wucknitz, Anna M. M. Scaife, Jason W. T. Hessels, J. Sluman, Aris Karastergiou, Gianni Bernardi, Mark J. Bentum, Michael Kramer, M. Pilia, George Heald, S. ter Veen, A. W. Gunst, H. Munk, H. J. A. Röttgering, A. S. van Amesfoort, E. de Geus, Satyendra Thoudam, Marcus Brüggen, C. Tasse, Harvey Butcher, John McKean, Emanuela Orru, Casey J. Law, M. Kuniyoshi, Chiara Ferrari, F. Breitling, Annalisa Bonafede, Joeri van Leeuwen, M. Pandey-Pommier, A. Zensus, James M. Anderson, Antonia Rowlinson, Ashish Asgekar, C. Toribio, R. Vermeulen, Joris P. W. Verbiest, Evan Keane, Matthias Hoeft, Vishal Gajjar, Jochen Eislöffel, S. Duscha, H. Paas, A. G. Polatidis, A. Alexov, Rebecca McFadden, Benedetta Ciardi, Stefan J. Wijnholds, J. W. Broderick, Richard Fallows, Wolfgang Reich, B. W. Stappers, A. Renting, F. de Gasperin, Adam T. Deller, W. Frieswijk, Martin Bell, Anna V. Bilous, R. J. van Weeren, I. M. Avruch, E. Juette, Patrick Weltevrede, J. P. Hamaker, A. J. van der Horst, Rene P. Breton, Kapteyn Astronomical Institute, Astronomy, Netherlands Institute for Radio Astronomy (ASTRON), University of Amsterdam [Amsterdam] (UvA), Jodrell Bank Centre for Astrophysics (JBCA), University of Manchester [Manchester], University of Southampton, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University [Nijmegen], Max-Planck-Institut für Radioastronomie (MPIFR), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), University of Oxford, Universität Bielefeld, Leibniz-Institut für Astrophysik Potsdam (AIP), SRON Netherlands Institute for Space Research (SRON), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, University of Edinburgh, Jacobs University [Bremen], Universität Hamburg (UHH), Max Planck Institute for Astrophysics, Max-Planck-Gesellschaft, Thüringer Landessternwarte Tautenburg (TLS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Leiden Observatory [Leiden], Universiteit Leiden, Ruhr-Universität Bochum [Bochum], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Oulu, Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy [Southampton], Rhodes University, Grahamstown, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ANR-09-JCJC-0001,OPALES(2009), European Project: 224838,EC:FP7:PEOPLE,FP7-PEOPLE-2007-4-3-IRG,PULSARS WITH LOFAR(2008), High Energy Astrophys. & Astropart. Phys (API, FNWI), Radboud university [Nijmegen], Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), University of Oxford [Oxford], Harvard University [Cambridge]-Smithsonian Institution, Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden [Leiden], École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Jodrell Bank Centre for Astrophysics, Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Smithsonian Institution-Harvard University [Cambridge], Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-09-JCJC-0001,OPALES,nOn-thermal Processes in gALaxy cluStErs(2009), Coenen, Thij, Van Leeuwen, Joeri, Hessels, Jason W. T., Stappers, Ben W., Kondratiev, Vladislav I., Alexov, A., Breton, R.P., Bilous, A., Cooper, S., Falcke, H., Fallows, R.A., Gajjar, V., Grießmeier, J.-M., Hassall, T.E., Karastergiou, A., Keane, E.F., Kramer, M., Kuniyoshi, M., Noutsos, A., Osłowski, S., Pilia, M., Serylak, M., Schrijvers, C., Sobey, C., Ter Veen, S., Verbiest, J., Weltevrede, P., Wijnholds, S., Zagkouris, K., Van Amesfoort, A.S., Anderson, J., Asgekar, A., Avruch, I.M., Bell, M.E., Bentum, M.J., Bernardi, G., Best, P., Bonafede, A., Breitling, F., Broderick, J., Brüggen, M., Butcher, H.R., Ciardi, B., Corstanje, A., Deller, A., Duscha, S., Eislöffel, J., Fender, R., Ferrari, C., Frieswijk, W., Garrett, M.A., De Gasperin, F., De Geus, E., Gunst, A.W., Hamaker, J.P., Heald, G., Hoeft, M., Van Der Horst, A., Juette, E., Kuper, G., Law, C., Mann, G., McFadden, R., McKay-Bukowski, D., McKean, J.P., Munk, H., Orru, E., Paas, H., Pandey-Pommier, M., Polatidis, A.G., Reich, W., Renting, A., Röttgering, H., Rowlinson, A., Scaife, A.M.M., Schwarz, D., Sluman, J., Smirnov, O., Swinbank, J., Tagger, M., Tang, Y., Tasse, C., Thoudam, S., Toribio, C., Vermeulen, R., Vocks, C., Van Weeren, R.J., Wucknitz, O., Zarka, P., and Zensus, A.
Subjects: EWI-25426, Aperture array, media_common.quotation_subject, Astronomy, Pilot survey, SPECTRAL INDEX, FOS: Physical sciences, Astrophysics, general [pulsars], METIS-309729, MHZ, Pulsar, surveys, pulsars: general, BURSTS, Survey, Telescope, POPULATION, Solar and Stellar Astrophysics (astro-ph.SR), media_common, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), [PHYS]Physics [physics], ORIGIN, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, telescopes, BINARY, LOFAR, Astronomy and Astrophysic, IR-93231, Astrophysics - Solar and Stellar Astrophysics, Sky, Space and Planetary Science, DISCOVERY, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, STATE CHANGE, Antenna (radio), ALLEN TELESCOPE ARRAY, EMISSION, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena
Abstract: We have conducted two pilot surveys for radio pulsars and fast transients with the Low-Frequency Array (LOFAR) around 140 MHz and here report on the first low-frequency fast-radio burst limit and the discovery of two new pulsars. The first survey, the LOFAR Pilot Pulsar Survey (LPPS), observed a large fraction of the northern sky, ~1.4 x 10^4 sq. deg, with 1-hr dwell times. Each observation covered ~75 sq. deg using 7 independent fields formed by incoherently summing the high-band antenna fields. The second pilot survey, the LOFAR Tied-Array Survey (LOTAS), spanned ~600 sq. deg, with roughly a 5-fold increase in sensitivity compared with LPPS. Using a coherent sum of the 6 LOFAR "Superterp" stations, we formed 19 tied-array beams, together covering 4 sq. deg per pointing. From LPPS we derive a limit on the occurrence, at 142 MHz, of dispersed radio bursts of < 150 /day/sky, for bursts brighter than S > 107 Jy for the narrowest searched burst duration of 0.66 ms. In LPPS, we re-detected 65 previously known pulsars. LOTAS discovered two pulsars, the first with LOFAR or any digital aperture array. LOTAS also re-detected 27 previously known pulsars. These pilot studies show that LOFAR can efficiently carry out all-sky surveys for pulsars and fast transients, and they set the stage for further surveying efforts using LOFAR and the planned low-frequency component of the Square Kilometer Array., 18 pages, 10 figures, accepted for A&A
Published: 2014

91. Improving the precision of pulsar timing through polarization statistics

Author: Paul Demorest, Stefan Oslowski, Matthew Bailes, and W. van Straten
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), business.industry, Gravitational wave, FOS: Physical sciences, Astronomy and Astrophysics, Impulse (physics), Polarization (waves), Residual, Root mean square, symbols.namesake, Optics, Pulsar, Space and Planetary Science, Faraday effect, symbols, Wideband, business, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: At the highest levels of pulsar timing precision achieved to date, experiments are limited by noise intrinsic to the pulsar. This stochastic wideband impulse modulated self-noise (SWIMS) limits pulsar timing precision by randomly biasing the measured times of arrival and thus increasing the root mean square (rms) timing residual. We discuss an improved methodology of removing this bias in the measured times of arrival by including information about polarized radiation. Observations of J0437-4715 made over a one-week interval at the Parkes Observatory are used to demonstrate a nearly 40 per cent improvement in the rms timing residual with this extended analysis. In this way, based on the observations over a 64 MHz bandwidth centred at 1341 MHz with integrations over 16.78 s we achieve a 476 ns rms timing residual. In the absence of systematic error, these results lead to a predicted rms timing residual of 30 ns in one hour integrations; however the data are currently limited by variable Faraday rotation in the Earth's ionosphere. The improvement demonstrated in this work provides an opportunity to increase the sensitivity in various pulsar timing experiments, for example pulsar timing arrays that pursue the detection of the stochastic background of gravitational waves. The fractional improvement is highly dependent on the properties of the pulse profile and the stochastic wideband impulse modulated self-noise of the pulsar in question., Comment: 11 pages, 8 figures, accepted for publication in MNRAS
Published: 2013
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92. Gravitational-wave Limits from Pulsar Timing Constrain Supermassive Black Hole Evolution

Author: Vikram Ravi, W. van Straten, Sarah Burke-Spolaor, Joris P. W. Verbiest, N. D. R. Bhat, Yuri Levin, J. Khoo, J. S. B. Wyithe, Michael Keith, John Sarkissian, Ryan Shannon, William A. Coles, Matthew Bailes, J. B. Wang, Richard N. Manchester, George Hobbs, and Stefan Oslowski
Subjects: Physics, Supermassive black hole, education.field_of_study, Active galactic nucleus, Multidisciplinary, Cosmology and Nongalactic Astrophysics (astro-ph.CO), General Science & Technology, 010308 nuclear & particles physics, Gravitational wave, Population, Astronomy, FOS: Physical sciences, Astrophysics, 01 natural sciences, Black hole, Pulsar timing array, Pulsar, 0103 physical sciences, Galaxy formation and evolution, education, 010303 astronomy & astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The formation and growth processes of supermassive black holes (SMBHs) are not well constrained. SMBH population models, however, provide specific predictions for the properties of the gravitational-wave background (GWB) from binary SMBHs in merging galaxies throughout the Universe. Using observations from the Parkes Pulsar Timing Array, we constrain the fractional GWB energy density with 95% confidence to be ${\Omega}_{GW}(H_0/73 {\rm km} {\rm s}^{-1} {\rm Mpc}^{-1})^2 < 1.3 \times 10^{-9}$ at a frequency of 2.8 nHz, which is approximately a factor of six more stringent than previous limits. We compare our limit to models of the SMBH population and find inconsistencies at confidence levels between 46% and 91%. For example, the standard galaxy formation model implemented in the Millennium simulations is inconsistent with our limit with 50% probability., Comment: Published in Science 18 October 2013
Published: 2013
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93. Development of a pulsar-based time-scale

Author: Jonathan Khoo, Ryan Shannon, Matthew Bailes, Yuri Levin, D. J. Champion, N. D. R. Bhat, George Hobbs, R. N. Manchester, W. van Straten, A. Chaudhary, Stefan Oslowski, D. R. B. Yardley, Aidan Hotan, D. Chen, X. P. You, B. Preisig, John Reynolds, Vikram Ravi, Sarah Burke-Spolaor, Jonathon Kocz, John Sarkissian, Michael Keith, Joris P. W. Verbiest, and William A. Coles
Subjects: Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Stability (probability), Pulsar timing array, Pulsar, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Terrestrial Time, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Using observations of pulsars from the Parkes Pulsar Timing Array (PPTA) project we develop the first pulsar-based timescale that has a precision comparable to the uncertainties in international atomic timescales. Our ensemble of pulsars provides an Ensemble Pulsar Scale (EPS) analogous to the free atomic timescale Echelle Atomique Libre (EAL). The EPS can be used to detect fluctuations in atomic timescales and therefore can lead to a new realisation of Terrestrial Time, TT(PPTA11). We successfully follow features known to affect the frequency of the International Atomic Timescale (TAI) and we find marginally significant differences between TT(PPTA11) and TT(BIPM11). We discuss the various phenomena that lead to a correlated signal in the pulsar timing residuals and therefore limit the stability of the pulsar timescale., Accepted for publication in MNRAS
Published: 2012

94. Measurement and correction of variations in interstellar dispersion in high-precision pulsar timing

Author: Stefan Oslowski, D. J. Champion, N. D. R. Bhat, Matthew Bailes, John Reynolds, Jonathon Kocz, Richard N. Manchester, Sarah Burke-Spolaor, D. R. B. Yardley, A. Chaudhary, Michael Keith, George Hobbs, Ryan Shannon, Aidan Hotan, Jonathan Khoo, John Sarkissian, Vikram Ravi, William A. Coles, and W. van Straten
Subjects: Physics, Scintillation, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, White noise, Astrophysics - Astrophysics of Galaxies, Gravitational wave background, Interstellar medium, Pulsar timing array, Wavelength, Pulsar, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Colors of noise, Astrophysics of Galaxies (astro-ph.GA), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: Signals from radio pulsars show a wavelength-dependent delay due to dispersion in the interstellar plasma. At a typical observing wavelength, this delay can vary by tens of microseconds on five-year time scales, far in excess of signals of interest to pulsar timing arrays, such as that induced by a gravitational-wave background. Measurement of these delay variations is not only crucial for the detection of such signals, but also provides an unparallelled measurement of the turbulent interstellar plasma at au scales. In this paper we demonstrate that without consideration of wavelength- independent red-noise, 'simple' algorithms to correct for interstellar dispersion can attenuate signals of interest to pulsar timing arrays. We present a robust method for this correction, which we validate through simulations, and apply it to observations from the Parkes Pulsar Timing Array. Correction for dispersion variations comes at a cost of increased band-limited white noise. We discuss scheduling to minimise this additional noise, and factors, such as scintillation, that can exacerbate the problem. Comparison with scintillation measurements confirms previous results that the spectral exponent of electron density variations in the interstellar medium often appears steeper than expected. We also find a discrete change in dispersion measure of PSR J1603-7202 of ~2x10^{-3} cm^{-3}pc for about 250 days. We speculate that this has a similar origin to the 'extreme scattering events' seen in other sources. In addition, we find that four pulsars show a wavelength-dependent annual variation, indicating a persistent gradient of electron density on an au spatial scale, which has not been reported previously., 16 pages, 8 figures. Accepted for publication in MNRAS
Published: 2012

95. The Parkes Pulsar Timing Array Project

Author: A. Brown, Sarah Burke-Spolaor, Grant Hampson, Jonathon Kocz, Stefan Oslowski, A. Chaudhary, John Sarkissian, Joris P. W. Verbiest, J. R. Reynolds, X. P. You, W. van Straten, J. Khoo, Fredrick A. Jenet, Z. L. Wen, Richard N. Manchester, Andrew Jameson, W. M. Yan, Matthew Bailes, Vikram Ravi, Michael Keith, Russell T. Edwards, N. D. R. Bhat, Ryan Shannon, Krzysztof Maciesiak, W. E. Wilson, William A. Coles, Aidan Hotan, M. J. Kesteven, George Hobbs, David Champion, and D. Yardley
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Static timing analysis, FOS: Physical sciences, Celestial sphere, Astronomy and Astrophysics, Radio telescope, Pulsar timing array, Pulsar, Millisecond pulsar, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Instrumentation and Methods for Astrophysics (astro-ph.IM), Noise (radio)
Abstract: A "pulsar timing array" (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of "global" phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 millisecond pulsars is being observed at three radio-frequency bands, 50cm (~700 MHz), 20cm (~1400 MHz) and 10cm (~3100 MHz), with observations at intervals of 2 - 3 weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For ten of the 20 pulsars, rms timing residuals are less than 1 microsec for the best band after fitting for pulse frequency and its first time derivative. Significant "red" timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array (IPTA) and a PTA based on the Square Kilometre Array. We also present an "extended PPTA" data set that combines PPTA data with earlier Parkes timing data for these pulsars., 36 pages, 13 figures, accepted by Publications of the Astronomical Society of Australia (PASA)
Published: 2012

96. Pulsar data analysis with PSRCHIVE

Author: Straten, Willem, Demorest, Paul, and Stefan Oslowski
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: PSRCHIVE is an open-source, object-oriented, scientific data analysis software library and application suite for pulsar astronomy. It implements an extensive range of general-purpose algorithms for use in data calibration and integration, statistical analysis and modeling, and visualisation. These are utilised by a variety of applications specialised for tasks such as pulsar timing, polarimetry, radio frequency interference mitigation, and pulse variability studies. This paper presents a general overview of PSRCHIVE functionality with some focus on the integrated interfaces developed for the core applications., 21 pages, 5 figures; tutorial presented at IPTA 2010 meeting in Leiden merged with talk presented at 2011 pulsar conference in Beijing; includes further research and development on algorithms for RFI mitigation and TOA bias correction
Published: 2012

97. The International Pulsar Timing Array project: using pulsars as a gravitational wave detector

Author: Matthew Bailes, V. M. Kaspi, David Champion, Kejia Lee, Ryan Shannon, X. P. You, M. Burgay, K. Lazaridis, Michael Kramer, M. B. Purver, D. R. B. Yardley, Duncan R. Lorimer, Paul Demorest, Andrea N. Lommen, Alberto Sesana, Joseph Lazio, William A. Coles, Fredrick A. Jenet, Christine Jordan, Jason W. T. Hessels, M. Pilia, Gregory Desvignes, Scott M. Ransom, S. Sanidas, Gilles Theureau, Ismaël Cognard, Andrea Possenti, David J. Nice, Daniel R. Stinebring, Paulo C. C. Freire, Ben Stappers, Ingrid H. Stairs, Robert D. Ferdman, Lee Samuel Finn, Anne M. Archibald, R. van Haasteren, George Hobbs, Stefan Oslowski, John Reynolds, Xavier Siemens, J. M. Cordes, Richard N. Manchester, Gemma H. Janssen, Zaven Arzoumanian, Yuri Levin, John Sarkissian, V. I. Kondratiev, Andrew Lyne, W. van Straten, Ryan S. Lynch, Sarah Burke-Spolaor, A. Jessner, Maura McLaughlin, Joris P. W. Verbiest, N. D. R. Bhat, Marjorie Gonzalez, Aidan Hotan, Donald C. Backer, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, Gravitational-wave observatory, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Binary number, Astrophysics, Galaxy merger, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, General Relativity and Quantum Cosmology, Astrophysics - Solar and Stellar Astrophysics, Pulsar, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, International Pulsar Timing Array
Abstract: The International Pulsar Timing Array project combines observations of pulsars from both Northern and Southern hemisphere observatories with the main aim of detecting ultra-low frequency (~10^-9 to 10^-8 Hz) gravitational waves. Here we introduce the project, review the methods used to search for gravitational waves emitted from coalescing supermassive binary black-hole systems in the centres of merging galaxies and discuss the status of the project., accepted by Classical and Quantum Gravity. Review talk for the Amaldi8 conference series
Published: 2010
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98. Status Update of the Parkes Pulsar Timing Array

Author: Aidan Hotan, Stefan Oslowski, David Champion, J. Khoo, D. R. B. Yardley, Kejia Lee, William A. Coles, Sarah Burke-Spolaor, Richard N. Manchester, W. van Straten, Joris P. W. Verbiest, John Sarkissian, X. P. You, N. D. R. Bhat, Matthew Bailes, John Reynolds, Andrea N. Lommen, Fredrick A. Jenet, and George Hobbs
Subjects: Physics, Pulsar timing array, General Relativity and Quantum Cosmology, Physics and Astronomy (miscellaneous), Millisecond pulsar, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract: The Parkes Pulsar Timing Array project aims to make a direct detection of a gravitational-wave background through timing of millisecond pulsars. In this article, the main requirements for that endeavour are described and recent and ongoing progress is outlined. We demonstrate that the timing properties of millisecond pulsars are adequate and that technological progress is timely to expect a successful detection of gravitational waves within a decade, or alternatively to rule out all current predictions for gravitational wave backgrounds formed by supermassive black-hole mergers., Comment: 10 pages, 3 figures, Amaldi 8 conference proceedings, accepted by Classical & Quantum Gravity
Published: 2009
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99. The PULSE@Parkes project: A new observing technique for long-term pulsar monitoring

Author: Stefan Oslowski, Matthew Carr, W. van Straten, M. Mulcahy, Fredrick A. Jenet, J. Chapman, J. Khoo, George Hobbs, David Champion, S. W. Amy, David H. McKinnon, D. R. B. Yardley, A. Kovacevic, Minnie Mao, Robert Hollow, M. Burgay, B. Homewood, Michael Keith, Sarah Burke-Spolaor, and Lena Danaia
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Pulse (physics), Term (time), Radio telescope, Pulsar timing array, Astrophysics - Solar and Stellar Astrophysics, Pulsar, Space and Planetary Science, Observatory, Noise (radio), Solar and Stellar Astrophysics (astro-ph.SR), Radio astronomy
Abstract: The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets., Comment: accepted for publication by PASA
Published: 2009
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100. Gravitational lensing as a probe of compact object population in the Galaxy

Author: Krzysztof Belczynski, Tomasz Bulik, Stefan Oslowski, and R. Moderski
Subjects: Physics, education.field_of_study, Population, Galactic Center, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, Gravitational microlensing, Galaxy, Neutron star, Gravitational lens, Space and Planetary Science, Binary star, education, Astrophysics::Galaxy Astrophysics
Abstract: The population of solitary compact objects in the Galaxy is very diffcult to investigate. In this paper we analyze the possibility of using microlensing searches to detect and to analyze the properties of the solitary black holes and neutron stars. Evolution of single and binary stars is considered using the StarTrack population synthesis code. We investigate the properties of the Galactic population of compact objects numerically. We find that the compact object lensing events are concentrated in a region with the radius of $\approx 5$ degrees around the Galactic center. The distribution of masses of the lenses for the models we consider differs but only slightly from the underlying massdistribution. The expected detection rates are of the order of a few per year., Submitted to Astronomy and Astrophysics
Published: 2006

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