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1. Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries

Author

Clark, C. J., Kerr, M., Barr, E. D., Bhattacharyya, B., Breton, R. P., Bruel, P., Camilo, F., Chen, W., Cognard, I., Cromartie, H. T., Deneva, J., Dhillon, V. S., Guillemot, L., Kennedy, M. R., Kramer, M., Lyne, A. G., Sánchez, D. Mata, Nieder, L., Phillips, C., Ransom, S. M., Ray, P. S., Roberts, M. S. E., Roy, J., Smith, D. A., Spiewak, R., Stappers, B. W., Tabassum, S., Theureau, G., and Voisin, G.

Published
2023
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2. Relativistic Shapiro delay measurements of an extremely massive millisecond pulsar

Author

Cromartie, H. T., Fonseca, E., Ransom, S. M., Demorest, P. B., Arzoumanian, Z., Blumer, H., Brook, P. R., DeCesar, M. E., Dolch, T., Ellis, J. A., Ferdman, R. D., Ferrara, E. C., Garver-Daniels, N., Gentile, P. A., Jones, M. L., Lam, M. T., Lorimer, D. R., Lynch, R. S., McLaughlin, M. A., Ng, C., Nice, D. J., Pennucci, T. T., Spiewak, R., Stairs, I. H., Stovall, K., Swiggum, J. K., and Zhu, W. W.

Published
2020
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3. MeerKAT Pulsar Timing Array parallaxes and proper motions.

Author

Shamohammadi, M, Bailes, M, Flynn, C, Reardon, D J, Shannon, R M, Buchner, S, Cameron, A D, Camilo, F, Coronigu, A, Geyer, M, Kramer, M, Miles, M, and Spiewak, R

Subjects
ORBITAL velocity, PULSARS, MEERKAT, GLOBULAR clusters, PARALLAX, RADIO telescopes, VELOCITY
Abstract

We have determined positions, proper motions, and parallaxes of 77 millisecond pulsars (MSPs) from ∼3 yr of MeerKAT radio telescope observations. Our timing and noise analyses enable us to measure 35 significant parallaxes (12 of them for the first time) and 69 significant proper motions. Eight pulsars near the ecliptic have an accurate proper motion in ecliptic longitude only. PSR J0955−6150 has a good upper limit on its very small proper motion (<0.4 mas yr−1). We used pulsars with accurate parallaxes to study the MSP velocities. This yields 39 MSP transverse velocities, and combined with MSPs in the literature (excluding those in Globular Clusters) we analyse 66 MSPs in total. We find that MSPs have, on average, much lower velocities than normal pulsars, with a mean transverse velocity of only 78(8) km s−1 (MSPs) compared with 246(21) km s−1 (normal pulsars). We found no statistical differences between the velocity distributions of isolated and binary MSPs. From Galactocentric cylindrical velocities of the MSPs, we derive 3D velocity dispersions of σρ, σϕ, σ z  = 63(11), 48(8), 19(3) km s−1. We measure a mean asymmetric drift with amplitude 38(11) km s−1, consistent with expectation for MSPs, given their velocity dispersions and ages. The MSP velocity distribution is consistent with binary evolution models that predict very few MSPs with velocities >300 km s−1 and a mild anticorrelation of transverse velocity with orbital period. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Practical approaches to analyzing PTA data: Cosmic strings with six pulsars

Author

Leclere, Hippolyte Quelquejay, Auclair, Pierre, Babak, Stanislav, Chalumeau, Aurélien, Steer, Danièle A., Antoniadis, J., Nielsen, A. -S. Bak, Bassa, C. G., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Desvignes, G., Falxa, M., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Graikou, E., Grießmeier, J. -M., Guillemot, L., Guo, Y. J., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Karuppusamy, R., Keane, E. F., Keith, M. J., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Main, R. A., Mickaliger, M. B., Niţu, I. C., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Speri, L., Spiewak, R., Stappers, B. W., Susarla, S. C., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, J. P. W., Wang, J., Wang, L., Wu, Z., 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)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), and EPTA

Subjects
High Energy Physics - Theory, kink, binary: mass, noise, data analysis method, Cosmology and Nongalactic Astrophysics (astro-ph.CO), gravitational radiation: stochastic, string tension, gravitational radiation: background, FOS: Physical sciences, statistical analysis: Bayesian, General Relativity and Quantum Cosmology (gr-qc), parametric, General Relativity and Quantum Cosmology, High Energy Physics - Theory (hep-th), black hole: binary, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], string: closed, string model, simplex, Astrophysics - Cosmology and Nongalactic Astrophysics, cosmic string: network, pulsar
Abstract

We search for a stochastic gravitational wave background (SGWB) generated by a network of cosmic strings using six millisecond pulsars from Data Release 2 (DR2) of the European Pulsar Timing Array (EPTA). We perform a Bayesian analysis considering two models for the network of cosmic string loops, and compare it to a simple power-law model which is expected from the population of supermassive black hole binaries. Our main strong assumption is that the previously reported common red noise process is a SGWB. We find that the one-parameter cosmic string model is slightly favored over a power-law model thanks to its simplicity. If we assume a two-component stochastic signal in the data (supermassive black hole binary population and the signal from cosmic strings), we get a $95\%$ upper limit on the string tension of $\log_{10}(Gμ) < -9.9$ ($-10.5$) for the two cosmic string models we consider. In extended two-parameter string models, we were unable to constrain the number of kinks. We test two approximate and fast Bayesian data analysis methods against the most rigorous analysis and find consistent results. These two fast and efficient methods are applicable to all SGWBs, independent of their source, and will be crucial for analysis of extended data sets., 13 pages, 5 figures

Published
2023

5. The second data release from the European Pulsar Timing Array IV. Search for continuous gravitational wave signals

Author

Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferranti, I., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Manzini, S., Mickaliger, M. B., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, Joris, Wang, J., Wang, L., Wu, Z., 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)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Laboratoire Univers et Théories (LUTH (UMR_8102))

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics of Galaxies (astro-ph.GA), [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the results of a search for continuous gravitational wave signals (CGWs) in the second data release (DR2) of the European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this search has a gravitational wave frequency of 4-5 nHz. Such a signal could be generated by a supermassive black hole binary (SMBHB) in the local Universe. We present the results of a follow-up analysis of this candidate using both Bayesian and frequentist methods. The Bayesian analysis gives a Bayes factor of 4 in favor of the presence of the CGW over a common uncorrelated noise process, while the frequentist analysis estimates the p-value of the candidate to be 1%, also assuming the presence of common uncorrelated red noise. However, comparing a model that includes both a CGW and a gravitational wave background (GWB) to a GWB only, the Bayes factor in favour of the CGW model is only 0.7. Therefore, we cannot conclusively determine the origin of the observed feature, but we cannot rule it out as a CGW source. We present results of simulations that demonstrate that data containing a weak gravitational wave background can be misinterpreted as data including a CGW and vice versa, providing two plausible explanations of the EPTA DR2 data. Further investigations combining data from all PTA collaborations will be needed to reveal the true origin of this feature., 12 figures, 15 pages, to be submitted

Published
2023

6. The second data release from the European Pulsar Timing Array: VI. Challenging the ultralight dark matter paradigm

Author

Smarra, Clemente, Goncharov, Boris, Barausse, Enrico, Antoniadis, J., Babak, S., Nielsen, A. -S. Bak, Bassa, C. G., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Desvignes, G., Falxa, M., Ferdman, R. D., Franchini, A., Gair, J. R., Graikou, E., Grie, J. -M., Guillemot, L., Guo, Y. J., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Karuppusamy, R., Keane, E. F., Keith, M. J., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Main, R. A., Mickaliger, M. B., Niţu, I. C., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Leclere, H. Quelquejay, Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Speri, L., Spiewak, R., Stappers, B. W., Susarla, S. C., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Wang, J., Wang, L., Wu, Z., 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)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), and European Pulsar Timing Array

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Cosmology and Nongalactic Astrophysics (astro-ph.CO), dark matter, interaction, density, local, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), GeV, Astrophysics - Astrophysics of Galaxies, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), gravitation, Astrophysics of Galaxies (astro-ph.GA), [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], galaxy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, pseudoscalar, dark matter, density, pulsar, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Pulsar Timing Array experiments probe the presence of possible scalar/pseudoscalar ultralight dark matter particles through decade-long timing of an ensemble of galactic millisecond radio pulsars. With the second data release of the European Pulsar Timing Array, we focus on the most robust scenario, in which dark matter interacts only gravitationally with ordinary baryonic matter. Our results show that ultralight particles with masses $10^{-24.0}~\text{eV} \lesssim m \lesssim 10^{-23.2}~\text{eV}$ cannot constitute $100\%$ of the measured local dark matter density, but can have at most local density $\rho\lesssim 0.15$ GeV/cm$^3$., Comment: 5 pages + acknowledgements + refs, 2 figures

Published
2023

7. Searching for continuous Gravitational Waves in the second data release of the International Pulsar Timing Array

Author

Falxa, M, Babak, S, Baker, P T, Bécsy, B, Chalumeau, A, Chen, S, Chen, Z, Cornish, N J, Guillemot, L, Hazboun, J S, Mingarelli, C M F, Parthasarathy, A, Petiteau, A, Pol, N S, Sesana, A, Spolaor, S B, Taylor, S R, Theureau, G, Vallisneri, M, Vigeland, S J, Witt, C A, Zhu, X, Antoniadis, J, Arzoumanian, Z, Bailes, M, Bhat, N D R, Blecha, L, Brazier, A, Brook, P R, Caballero, N, Cameron, A D, Casey-Clyde, J A, Champion, D, Charisi, M, Chatterjee, S, Cognard, I, Cordes, J M, Crawford, F, Cromartie, H T, Crowter, K, Dai, S, DeCesar, M E, Demorest, P B, Desvignes, G, Dolch, T, Drachler, B, Feng, Y, Ferrara, E C, Fiore, W, Fonseca, E, Garver-Daniels, N, Glaser, J, Goncharov, B, Good, D C, Griessmeier, J, Guo, Y J, Gültekin, K, Hobbs, G, Hu, H, Islo, K, Jang, J, Jennings, R J, Johnson, A D, Jones, M L, Kaczmarek, J, Kaiser, A R, Kaplan, D L, Keith, M, Kelley, L Z, Kerr, M, Key, J S, Laal, N, Lam, M T, Lamb, W G, Lazio, T J W, Liu, K, Liu, T, Luo, J, Lynch, R S, Madison, D R, Main, R, Manchester, R, McEwen, A, McKee, J, McLaughlin, M A, Ng, C, Nice, D J, Ocker, S, Olum, K D, Osłowski, S, Pennucci, T T, Perera, B B P, Perrodin, D, Porayko, N, Possenti, A, Quelquejay-Leclere, H, Ransom, S M, Ray, P S, Reardon, D J, Russell, C J, Samajdar, A, Sarkissian, J, Schult, L, Shaifullah, G, Shannon, R M, Shapiro-Albert, B J, Siemens, X, Simon, J J, Siwek, M, Smith, T L, Speri, L, Spiewak, R, Stairs, I H, Stappers, B, Stinebring, D R, Swiggum, J K, Tiburzi, C, Turner, J, Vecchio, A, Verbiest, Joris, Wahl, H, Wang, S Q, Wang, J, Wang, Jun, Wu, Ziwei, Zhang, L, Zhang, S, 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)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), and IPTA

Subjects
noise, data analysis method, gravitational radiation, orbit: circle, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), sensitivity, frequency: high, General Relativity and Quantum Cosmology, confidence limit, frequency: low, black hole: binary, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), pulsar
Abstract

The International Pulsar Timing Array 2nd data release is the combination ofdatasets from worldwide collaborations. In this study, we search for continuouswaves: gravitational wave signals produced by individual supermassive blackhole binaries in the local universe. We consider binaries on circular orbitsand neglect the evolution of orbital frequency over the observational span. Wefind no evidence for such signals and set sky averaged 95% upper limits ontheir amplitude h 95 . The most sensitive frequency is 10nHz with h 95 = 9.110-15 . We achieved the best upper limit to date at low and high frequencies ofthe PTA band thanks to improved effective cadence of observations. In ouranalysis, we have taken into account the recently discovered common red noiseprocess, which has an impact at low frequencies. We also find that the peculiarnoise features present in some pulsars data must be taken into account toreduce the false alarm. We show that using custom noise models is essential insearching for continuous gravitational wave signals and setting the upperlimit.

Published
2023
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8. The NANOGrav 11 Yr Data Set: Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries

Author

Aggarwal, K, Arzoumanian, Z, Baker, P. T, Brazier, A, Brinson, M. R, Brook, P. R, Burke-Spolaor, S, Chatterjee, S, Cordes, J. M, Cornish, N. J, Crawford, F, Crowter, K, Cromartie, H. T, DeCesar, M, Demorest, P. B, Dolch, T, Ellis, J. A, Ferdman, R. D, Ferrara, E, Fonseca, E, Garver-Daniels, N, Gentile, P, Hazboun, J. S, Holgado, A. M, Huerta, E. A, Islo, K, Jennings, R, Jones, G, Jones, M. L, Kaiser, A. R, Kaplan, D. L, Kelley, L. Z, Key, J. S, Lam, M. T, Lazio, T. J. W, Levin, L, Lorimer, D. R, Luo, J, Lynch, R. S, Madison, D. R, McLaughlin, M. A, McWilliams, S. T, Mingarelli, C. M. F, Ng, C, Nice, D. J, Pennucci, T. T, Pol, N. S, Ransom, S. M, Ray, P. S, Siemens, X, Simon, J, Spiewak, R, Stairs, I. H, Stinebring, D. R, Stovall, K, Swiggum, J, Taylor, S. R, Turner, J. E, Vallisneri, M, Haasteren, R. van, Vigeland, S. J, Witt, C. A, and Zhu, W. W

Subjects
Astrophysics
Abstract

Observations indicate that nearly all galaxies contain supermassive black holes at their centers. When galaxies merge, their component black holes form SMBH binaries (SMBHBs), which emit low-frequency gravitational waves (GWs) that can be detected by pulsar timing arrays. We have searched the North American Nanohertz Observatory for Gravitational Waves 11 yr data set for GWs from individual SMBHBs in circular orbits. As we did not find strong evidence for GWs in our data, we placed 95% upper limits on the strength of GWs from such sources. At f(gw) = 8 nHz, we placed a sky-averaged upper limit of h(0) < 7.3(3) × 10(exp −15). We also developed a technique to determine the significance of a particular signal in each pulsar using "dropout" parameters as a way of identifying spurious signals. From these upper limits, we ruled out SMBHBs emitting GWs f(gw) = 8 nHz within 120 Mpc for M = 10(exp 9) Solar Mass, and within 5.5 Gpc for M= 10(exp 10) Solar Mass at our most sensitive sky location. We also determined that there are no SMBHBs with M > 1.6 x 10(exp 9) Solar Mass emitting GWs with f(gw) = 2.8–317.8 nHz in the Virgo Cluster. Finally, we compared our strain upper limits to simulated populations of SMBHBs, based on galaxies in the Two Micron All-Sky Survey and merger rates from the Illustris cosmological simulation project, and found that only 34 out of 75,000 realizations of the local universe contained a detectable source.

Published
2019
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9. The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals

Author

Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. -S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. -M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Mickaliger, M. B., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, Joris, Wang, J., Wang, L., Wu, Z., 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)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and Laboratoire Univers et Théories (LUTH (UMR_8102))

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present the results of the search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using the second data release of the European Pulsar Timing Array (EPTA) for 25 millisecond pulsars and a combination with the first data release of the Indian Pulsar Timing Array (InPTA). We analysed (i) the full 24.7-year EPTA data set, (ii) its 10.3-year subset based on modern observing systems, (iii) the combination of the full data set with the first data release of the InPTA for ten commonly timed millisecond pulsars, and (iv) the combination of the 10.3-year subset with the InPTA data. These combinations allowed us to probe the contributions of instrumental noise and interstellar propagation effects. With the full data set, we find marginal evidence for a GWB, with a Bayes factor of four and a false alarm probability of $4\%$. With the 10.3-year subset, we report evidence for a GWB, with a Bayes factor of $60$ and a false alarm probability of about $0.1\%$ ($\gtrsim 3\sigma$ significance). The addition of the InPTA data yields results that are broadly consistent with the EPTA-only data sets, with the benefit of better noise modelling. Analyses were performed with different data processing pipelines to test the consistency of the results from independent software packages. The inferred spectrum from the latest EPTA data from new generation observing systems is rather uncertain and in mild tension with the common signal measured in the full data set. However, if the spectral index is fixed at 13/3, the two data sets give a similar amplitude of ($2.5\pm0.7)\times10^{-15}$ at a reference frequency of $1\,{\rm yr}^{-1}$. By continuing our detection efforts as part of the International Pulsar Timing Array (IPTA), we expect to be able to improve the measurement of spatial correlations and better characterise this signal in the coming years., Comment: 21 pages, 14 figures, 4 appendix figures, accepted for publication in A&A

Published
2023
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10. Mass measurements and 3D orbital geometry of PSR J1933$-$6211

Author

Geyer, M., Krishnan, V. Venkatraman, Freire, P. C. C., Kramer, M., Antoniadis, J., Bailes, M., Bernadich, M. C. i, Buchner, S., Cameron, A. D., Champion, D. J., Karastergiou, A., Keith, M. J., Lower, M. E., Osłowski, S., Possenti, A., Parthasarathy, A., Reardon, D. J., Serylak, M., Shannon, R. M., Spiewak, R., van Straten, W., and Verbiest, Joris

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

PSR J1933$-$6211 is a 3.5-ms pulsar in a 12.8-d orbit with a white dwarf (WD). Its high proper motion and low dispersion measure result in such significant interstellar scintillation that high signal-to-noise detections require long observing durations or fortuitous timing. We turn to the sensitive MeerKAT telescope and, combined with historic Parkes data, leverage PSR J1933$-$6211's kinematic and relativistic effects to constrain its 3D orbital geometry and the component masses. We obtain precise proper motion and parallax estimates, and measure their effects as secular changes in the Keplerian orbital parameters: a variation in orbital period of $7(1) \times 10^{-13}$ s s$^{-1}$ and a change in projected semi-major axis of $1.60(5) \times 10^{-14}$ s s$^{-1}$. A self-consistent analysis of all kinematic and relativistic effects yields a distance of $1.6^{+0.2}_{-0.3}$ kpc, an orbital inclination, $i = 55(1)$ deg and a longitude of the ascending node, $\Omega = 255^{+8}_{-14}$ deg. The probability densities for $\Omega$ and $i$ and their symmetric counterparts, ($180-i$, $360-\Omega$), are seen to depend on the fiducial orbit used to measure the time of periastron passage. We investigate this unexpected dependence and rule out software-related causes using simulations. Nevertheless, we constrain the pulsar and WD masses to $1.4^{+0.3}_{-0.2}$ M$_\odot$ and $0.43(5)$ M$_\odot$ respectively. These strongly disfavour a helium-dominated WD. The orbital similarities between PSRs J1933$-$6211 and J1614$-$2230 suggest they underwent Case A Roche lobe overflow, an extended evolution while the companion star is still on the Main Sequence. However, with a mass of $\sim 1.4$ M$_\odot$, PSR J1933$-$6211 has not accreted significant matter. This highlights the low accretion efficiency of the spin-up process and suggests that observed neutron star masses are mostly a result of supernova physics., Comment: 16 pages, 7 figures. Abstract shortened to adhere to ArXiv limit

Published
2023

11. The NANOGrav 12.5 yr Data Set: The Frequency Dependence of Pulse Jitter in Precision Millisecond Pulsars

Author

Lam, M. T, McLaughlin, M. A, Arzoumanian, Z, Blumer, H, Brook, P. R, Cromartie, H. T, Demorest, P. B, DeCesar, M. E, Dolch, T, Ellis, J. A, Ferdman, R. D, Ferrara, E. C, Fonesca, E, Garver-Daniels, N, Gentile, P. A, Jones, M. L, Lorimer, D. R, Lynch, R. S, Ng, C, Nice, D. J, Pennucci, T. T, Ranson, S. M, Spiewak, R, Stairs, I. H, Stovall, K, Swiggum, J. K, Vigeland, S. J, and Zhu, W. W

Subjects
Astrophysics
Abstract

Low-frequency gravitational-wave experiments require the highest timing precision from an array of the moststable millisecond pulsars. Several known sources of noise on short timescales in single radio pulsar observationsare well described by a simple model of three components: template fitting from a finite signal-to-noise ratio, pulsephase/amplitude jitter from single-pulse stochasticity, and scintillation errors from short-timescale interstellarscattering variations. Currently template-fitting errors dominate, but as radio telescopes push toward higher signalto-noise ratios, jitter becomes the next dominant term for most millisecond pulsars. Understanding the statistics ofjitter becomes crucial for properly characterizing arrival time uncertainties. We characterize the radio frequencydependence of jitter using data on 48 pulsars in the North American Nanohertz Observatory for GravitationalWaves timing program. We detect significant jitter in 43 of the pulsars and test several functional forms for itsfrequency dependence; we find significant frequency dependence for 30 pulsars. We find moderate correlations ofrms jitter with pulse width (R = 0.62) and number of profile components (R = 0.40); the single-pulse rms jitter istypically 1% of pulse phase. The average frequency dependence for all pulsars using a power-law model hasindex 0.42. We investigate the jitter variations for the interpulse of PSR B1937+21 and find no significantdeviations from the main pulse rms jitter. We also test the time variation of jitter in two pulsars and find thatsystematics likely bias the results for high-precision pulsars. Pulsar timing array analyses must properly modeljitter as a significant component of the noise within the detector.

Published
2019
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12. The NANOGrav 11 yr Data Set: Solar Wind Sounding through Pulsar Timing

Author

Madison, D.R, Cordes, J.M, Arzoumanian, Z, Chatterjee, S, Crowter, K, DeCesar, M. E, Demorest, P. B, Dolch, T, Ellis, J. A, Ferdman, R. D, Ferrara, E. C, Fonseca, E, Gentile, P. A, Jones, G, Jones, M. L, Lam, M. T, Levin, L, Lorimer, D. R, Lynch, R. S, McLaughlin, M. A, Mingarelli, C. M. F, Ng, C, Nice, D. J, Pennucci, T. T, Ransom, S. M, Ray, P. S, Spiewak, R, Stairs, I. H, Stovall, K, Swiggum, J. K, and Zhu, W. W

Subjects
Astronomy, Astrophysics
Abstract

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has observed dozens ofmillisecond pulsars for over a decade. We have accrued a large collection of dispersion measure (DM)measurements sensitive to the total electron content between Earth and the pulsars at each observation. All lines ofsight cross through the solar wind (SW), which produces correlated DM fluctuations in all pulsars. We develop andapply techniques for extracting the imprint of the SW from the full collection of DM measurements in the recentlyreleased NANOGrav 11 yr data set. We filter out long-timescale DM fluctuations attributable to structure in theinterstellar medium and carry out a simultaneous analysis of all pulsars in our sample that can differentiate thecorrelated signature of the wind from signals unique to individual lines of sight. When treating the SW asspherically symmetric and constant in time, we find the electron number density at 1au to be 7.9 ± 0.2 cm(exp -3). Wefind our data to be insensitive to long-term variation in the density of the wind. We argue that our techniques pairedwith a high-cadence, low-radio-frequency observing campaign of near-ecliptic pulsars would be capable ofmapping out large-scale latitudinal structure in the wind.

Published
2019
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13. The NANOGrav 11 Year Data Set: Pulsar-Timing Constraints on the Stochastic Gravitational-Wave Background

Author

Arzoumanian, Z, Baker, P. T, Brazier, A, Burke-Spolaor, S, Chamberlin, S. J, Chatterjee, S, Christy, B, Cordes, J. M, Cornish, N. J, Crawford, F, Cromartie, H. Thankful, Crowter, K, DeCesar, M, Demorest, P. B, Dolch, T, Ellis, J. A, Ferdman, R. D, Ferrara, E, Folkner, W. M, Fonseca, E, Garver-Daniels, N, Gentile, P. A, Haas, R, Hazboun, J. S, Huerta, E. A, Islo, K, Jones, G, Jones, M. L, Kaplan, D. L, Kaspi, V. M, Lam, M. T, Lazio, T. J. W, Levin, L, Lommen, A. N, Lorimer, D. R, Luo, J, Lynch, R. S, Madison, D. R, McLaughlin, M. A, McWilliams, S. T, Mingarelli, C. M. F, Ng, C, Nice, D. J, Park, R. S, Pennucci, T. T, Pol, N. S, Ransom, S. M, Ray, P. S, Rasskazov, A, Siemens, X, Simon, J, Spiewak, R, Stairs, I. H, Stinebring, D. R, Stovall, K, Swiggum, J, Taylor, S. R, Vallisneri, M, van Haasteren, R, Vigeland, S, and Zhu, W. W

Subjects
Astrophysics
Abstract

We search for an isotropic stochastic gravitational-wave background (GWB) in the newly released 11 year data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). While we find no evidence for a GWB, we place constraints on a population of inspiraling supermassive black hole (SMBH) binaries, a network of decaying cosmic strings, and a primordial GWB. For the first time, we find that the GWB constraints are sensitive to the solar system ephemeris (SSE) model used and that SSE errors can mimic a GWB signal. We developed an approach that bridges systematic SSE differences, producing the first pulsar-timing array (PTA) constraints that are robust against SSE errors. We thus place a 95% upper limit on the GW-strain amplitude of A (sub GWB) < 1.45 × 10 (exp -15) at a frequency of f=1 yr(exp -1) for a fiducial f (exp -2/3) power-law spectrum and with interpulsar correlations modeled. This is a factor of approximately 2 improvement over the NANOGrav nine-year limit calculated using the same procedure. Previous PTA upper limits on the GWB (as well as their astrophysical and cosmological interpretations) will need revision in light of SSE systematic errors. We use our constraints to characterize the combined influence on the GWB of the stellar mass density in galactic cores, the eccentricity of SMBH binaries, and SMBH-galactic-bulge scaling relationships. We constrain the cosmic-string tension using recent simulations, yielding an SSE-marginalized 95% upper limit of G (sub mu) < 5.3 × 10(exp -11) - a factor of approximately 2 better than the published NANOGrav nine-year constraints. Our SSE-marginalized 95% upper limit on the energy density of a primordial GWB (for a radiation-dominated post-inflation universe) is omega (sub GWB)(f) h (exp 2) < 3.4 × 10 (exp -10).

Published
2018
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14. A gamma-ray pulsar timing array constrains the nanohertz gravitational wave background

Author

Ajello, M., Atwood, W.B., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Berretta, A., Bhattacharyya, B., Bissaldi, E., Blandford, R.D., Bloom, E., Bonino, R., Bruel, P., Buehler, R., Burns, E., Buson, S., Cameron, R.A., Caraveo, P.A., Cavazzuti, E., Cibrario, N., Ciprini, S., Clark, C.J., Cognard, I., Coronado-Blazquez, J., Crnogorcevic, M., Cromartie, H., Crowter, K., Cutini, S., d'Ammando, F., de Gaetano, S., de Palma, F., Digel, S.W., Di Lalla, N., Dirirsa, F. Fana, Di Venere, L., Domínguez, A., Ferrara, E.C., Fiori, A., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gammaldi, V., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Green, D., Grenier, I.A., Guillemot, L., Guiriec, S., Gustafsson, M., Harding, A.K., Hays, E., Hewitt, J.W., Horan, D., Hou, X., Johannesson, G., Keith, M.J., Kerr, M., Kramer, M., Kuss, M., Larsson, S., Latronico, L., Li, J., Longo, F., Loparco, F., Lovellette, M.N., Lubrano, P., Maldera, S., Manfreda, A., Martí-Devesa, G., Mazziotta, M.N., Mereu, I., Michelson, P.F., Mirabal, N., Mitthumsiri, W., Mizuno, T., Monzani, M.E., Morselli, A., Negro, M., Nieder, L., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Ormes, J.F., Paneque, D., Parthasarathy, A., Pei, Z., Persic, M., Pesce-Rollins, M., Pillera, R., Poon, H., Porter, T.A., Principe, G., Racusin, J.L., Raino, S., Rando, R., Rani, B., Ransom, S.M., Ray, P.S., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Roy, J., Sanchez-Conde, M., Saz Parkinson, P.M., Scargle, J., Scotton, L., Serini, D., Sgro, C., Siskind, E.J., Smith, D.A., Spandre, G., Spiewak, R., Spinelli, P., Stairs, I., Suson, D.J., Swihart, S.J., Tabassum, S., Thayer, J.B., Theureau, G., Torres, D.F., Troja, E., Valverde, J., Wadiasingh, Z., Wood, K., Zaharijas, G., UAM. Departamento de Física Teórica, Ajello, M., Atwood, W. B., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Berretta, A., Bhattacharyya, B., Bissaldi, E., Blandford, R. D., Bloom, E., Bonino, R., Bruel, P., Buehler, R., Burns, E., Buson, S., Cameron, R. A., Caraveo, P. A., Cavazzuti, E., Cibrario, N., Ciprini, S., Clark, C. J., Cognard, I., Coronado-Bl??zquez, J., Crnogorcevic, M., Cromartie, H., Crowter, K., Cutini, S., D'Ammando, F., De Gaetano, S., de Palma, F., Digel, S. W., Di Lalla, N., Fana Dirirsa, F., Di Venere, L., Dom??nguez, A., Ferrara, E. C., Fiori, A., Franckowiak, A., Fukazawa, Y., Funk, S., Fusco, P., Gammaldi, V., Gargano, F., Gasparrini, D., Giglietto, N., Giordano, F., Giroletti, M., Green, D., Grenier, I. A., Guillemot, L., Guiriec, S., Gustafsson, M., Harding, A. K., Hays, E., Hewitt, J. W., Horan, D., Hou, X., J??hannesson, G., Keith, M. J., Kerr, M., Kramer, M., Kuss, M., Larsson, S., Latronico, L., Li, J., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Maldera, S., Manfreda, A., Mart??-Devesa, G., Mazziotta, M. N., Mereu, I., Michelson, P. F., Mirabal, N., Mitthumsiri, W., Mizuno, T., Monzani, M. E., Morselli, A., Negro, M., Nieder, L., Ojha, R., Omodei, N., Orienti, M., Orlando, E., Ormes, J. F., Paneque, D., Parthasarathy, A., Pei, Z., Persic, M., Pesce-Rollins, M., Pillera, R., Poon, H., Porter, T. A., Principe, G., Racusin, J. L., Rain??, S., Rando, R., Rani, B., Ransom, S. M., Ray, P. S., Razzano, M., Razzaque, S., Reimer, A., Reimer, O., Roy, J., S??nchez-Conde, M., Saz Parkinson, P. M., Scargle, J., Scotton, L., Serini, D., Sgr??, C., Siskind, E. J., Smith, D. A., Spandre, G., Spiewak, R., Spinelli, P., Stairs, I., Suson, D. J., Swihart, S. J., Tabassum, S., Thayer, J. B., Theureau, G., Torres, D. F., Troja, E., Valverde, J., Wadiasingh, Z., Wood, K., Zaharijas, G., 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), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-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), 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), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Fermi-LAT

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Gravitational Waves, astro-ph.HE, noise, radio wave, Multidisciplinary, Astrophysics::High Energy Astrophysical Phenomena, gravitational radiation: background, DEAE-Dextran, binary, FOS: Physical sciences, Física, Diethylaminoethyldextran, GLAST, monitoring, gamma ray, black hole, galaxy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Pulsars, pulsar
Abstract

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiere, La Editorial no permite publicar la versión editorial, After large galaxies merge, their central supermassive black holes are expected to form binary systems. Their orbital motion should generate a gravitational wave background (GWB) at nanohertz frequencies. Searches for this background use pulsar timing arrays, which perform long-term monitoring of millisecond pulsars at radio wavelengths. We used 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 × 10-14 at a frequency of 1 year-1. The sensitivity is expected to scale with tobs, the observing time span, as t-13/6obs. This direct measurement provides an independent probe of the GWB while offering a check on radio noise models

Published
2022
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15. European Surveillance System on Contact Allergies (ESSCA): results with the European baseline series, 2013/14

Author

Uter, W., Amario‐Hita, J.C., Balato, A., Ballmer‐Weber, B., Bauer, A., Belloni Fortina, A., Bircher, A., Chowdhury, M.M.U., Cooper, S.M., Czarnecka‐Operacz, M., Dugonik, A., Gallo, R., Giménez‐Arnau, A., Johansen, J.D., John, S.M., Kieć‐Świerczyńska, M., Kmecl, T., Kręcisz, B., Larese Filon, F., Mahler, V., Pesonen, M., Rustemeyer, T., Sadowska‐Przytocka, A., Sánchez‐Pérez, J., Schliemann, S., Schuttelaar, M.L., Simon, D., Spiewak, R., Valiukevičienė, S., Weisshaar, E., White, I.R., and Wilkinson, S.M.

Published
2017
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16. Searches for Shapiro delay in seven binary pulsars using the MeerKAT telescope.

Author

Shamohammadi, M, Bailes, M, Freire, P C C, Parthasarathy, A, Reardon, D J, Shannon, R M, Venkatraman Krishnan, V, Bernadich, M C i, Cameron, A D, Champion, D J, Corongiu, A, Flynn, C, Geyer, M, Kramer, M, Miles, M T, Possenti, A, and Spiewak, R

Subjects
MEERKAT, BINARY pulsars, PULSARS, NEUTRON stars, DATA quality, SPACETIME, RADIO telescopes
Abstract

Precision timing of millisecond pulsars (MSPs) in binary systems enables observers to detect the relativistic Shapiro delay induced by space–time curvature. When favourably aligned, this enables constraints to be placed on the component masses and system orientation. Here, we present the results of timing campaigns on seven binary MSPs observed with the 64-antenna MeerKAT radio telescope that show evidence of Shapiro delay: PSRs J0101−6422, J1101−6424, J1125−6014, J1514−4946, J1614−2230, J1732−5049, and J1909−3744. Evidence for Shapiro delay was found in all of the systems, and for three the orientations and data quality enabled strong constraints on their orbital inclinations and component masses. For PSRs J1125−6014, J1614−2230, and J1909−3744, we determined pulsar masses to be |$M_{\rm p} = 1.68\pm 0.17$|⁠ , |$1.94\pm 0.03$|⁠ , and |$1.45 \pm 0.03 \, {\rm M_{\odot }}$|⁠ , and companion masses to be |$M_{\rm c} = 0.33\pm 0.02$|⁠ , |$0.495\pm 0.005$|⁠ , and |$0.205 \pm 0.003 \, {\rm M_{\odot }}$|⁠ , respectively. This provides the first independent confirmation of PSR J1614−2230's mass, one of the highest known. The Shapiro delays measured for PSRs J0101−6422, J1101−6424, J1514−4946, and J1732−5049 were only weak, and could not provide interesting component mass limits. Despite a large number of MSPs being routinely timed, relatively few have accurate masses via Shapiro delays. We use simulations to show that this is expected, and provide a formula for observers to assess how accurately a pulsar mass can be determined. We also discuss the observed correlation between pulsar companion masses and spin period, and the anticorrelation between recycled pulsar mass and their companion masses. [ABSTRACT FROM AUTHOR]

Published
2023
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17. The MeerKAT Pulsar Timing Array: first data release.

Author

Miles, M T, Shannon, R M, Bailes, M, Reardon, D J, Keith, M J, Cameron, A D, Parthasarathy, A, Shamohammadi, M, Spiewak, R, van Straten, W, Buchner, S, Camilo, F, Geyer, M, Karastergiou, A, Kramer, M, Serylak, M, Theureau, G, and Venkatraman Krishnan, V

Subjects
DATA release, PULSARS, MEERKAT, GRAVITATIONAL waves, COMMUNITIES
Abstract

We present the first 2.5 yr of data from the MeerKAT Pulsar Timing Array (MPTA), part of MeerTime, a MeerKAT Large Survey Project. The MPTA aims to precisely measure pulse arrival times from an ensemble of 88 pulsars visible from the Southern hemisphere, with the goal of contributing to the search, detection, and study of nanohertz-frequency gravitational waves as part of the International Pulsar Timing Array. This project makes use of the MeerKAT telescope and operates with a typical observing cadence of 2 weeks using the L-band receiver that records data from 856 to 1712 MHz. We provide a comprehensive description of the observing system, software, and pipelines used and developed for the MeerTime project. The data products made available as part of this data release are from the 78 pulsars that had at least 30 observations between the start of the MeerTime programme in February 2019 and October 2021. These include both sub-banded and band-averaged arrival times and the initial timing ephemerides, noise models, and the frequency-dependent standard templates (portraits) used to derive pulse arrival times. After accounting for detected noise processes in the data, the frequency-averaged residuals of 67 of the pulsars achieved a root-mean-square residual precision of |$\lt 1 \, \mu \rm {s}$|⁠. We also present a novel recovery of the clock correction waveform solely from pulsar timing residuals and an exploration into preliminary findings of interest to the international pulsar timing community. The arrival times, standards, and full Stokes parameter-calibrated pulsar timing archives are publicly available. [ABSTRACT FROM AUTHOR]

Published
2023
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18. The NANOGrav 12.5-Year Data Set: Polarimetry, Rotation Measures, and Galactic Magnetic Field Strengths from NANOGrav Observations with the Green Bank Telescope

Author

Wahl, H.M., McLaughlin, M.A., Gentile, P.A., Jones, M.L., Spiewak, R., Arzoumanian, Z., Crowter, K., Demorest, P.B., DeCesar, M.E., Dolch, T., Ellis, J.A., Ferdman, R.D., Ferrara, E.C., Fonseca, E., Garver-Daniels, N., Jones, G., Lam, M.T., Levin, L., Lewandowska, N., Lorimer, D.R., Lynch, R.S., Madison, D.R., Ng, C., Nice, D.J., Pennucci, T.T., Ransom, S.M., Ray, P., Stairs, I.H., Stovall, K., Swiggum, J.K., and Zhu, W.W.

Subjects
Astrophysics and Astronomy, astro-ph.SR, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We present polarization profiles for 24 millisecond pulsars observed at 820 and 1500 MHz with the Green Bank Telescope by the NANOGrav pulsar timing array. We use Mueller matrix solutions calculated from observations of PSRs B1929+10 and J1022+1001 to calibrate the data. We discuss the polarization profiles, which can be used to constrain pulsar emission geometry, and also present the discovery of very low intensity average profile components ("microcomponents") in four pulsars. Using the rotation measures we measured for each pulsar, we calculate the Galactic magnetic field parallel to the line of sight for different lines of sight through the interstellar medium. We fit for linear and sinusoidal trends in time in the rotation measure, dispersion measure, and Galactic magnetic field. We detect rotation measure variations with a period of one year in some pulsars but overall find that the variations in these parameters are more consistent with a stochastic origin.

Published
2021

19. Discoveries and timing of pulsars in NGC 6440.

Author

Vleeschower, L, Stappers, B W, Bailes, M, Barr, E D, Kramer, M, Ransom, S, Ridolfi, A, Venkatraman Krishnan, V, Possenti, A, Keith, M J, Burgay, M, Freire, P C C, Spiewak, R, Champion, D J, Bezuidenhout, M C, Niţu, I C, Chen, W, Parthasarathy, A, DeCesar, M E, and Buchner, S

Subjects
BINARY pulsars, ECLIPSES, MARKOV chain Monte Carlo, PULSARS, MONTE Carlo method, RADIO telescopes, PULSAR detection
Abstract

Using the MeerKAT radio telescope, a series of observations have been conducted to time the known pulsars and search for new pulsars in the globular cluster NGC 6440. As a result, two pulsars have been discovered, NGC 6440G and NGC 6440H, one of which is isolated and the other a non-eclipsing (at frequencies above 962 MHz) 'Black Widow', with a very low mass companion (M c > 0.006 M⊙). It joins the other binary pulsars discovered so far in this cluster that all have low companion masses (M c < 0.30 M⊙). We present the results of long-term timing solutions obtained using data from both Green Bank and MeerKAT telescopes for these two new pulsars and an analysis of the pulsars NGC 6440C and NGC 6440D. For the isolated pulsar NGC 6440C, we searched for planets using a Markov chain Monte Carlo technique. We find evidence for significant unmodelled variations but they cannot be well modelled as planets nor as part of a power-law red-noise process. Studies of the eclipses of the 'Redback' pulsar NGC 6440D at two different frequency bands reveal a frequency dependence with longer and asymmetric eclipses at lower frequencies (962–1283 MHz). [ABSTRACT FROM AUTHOR]

Published
2022
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29. Mode changing in J1909 − 3744: the most precisely timed pulsar.

Author

Miles, M T, Shannon, R M, Bailes, M, Reardon, D J, Buchner, S, Middleton, H, and Spiewak, R

Subjects
PULSARS, SIGNAL-to-noise ratio, GRAVITATIONAL waves, NEUTRON stars, MEERKAT, BASEBAND
Abstract

We present baseband radio observations of the millisecond pulsar J1909 − 3744, the most precisely timed pulsar, using the MeerKAT telescope as part of the MeerTime pulsar timing array campaign. During a particularly bright scintillation event the pulsar showed strong evidence of pulse mode changing, among the first millisecond pulsars and the shortest duty cycle millisecond pulsar to do so. Two modes appear to be present, with the weak (lower signal-to-noise ratio) mode arriving 9.26 ± 3.94 μs earlier than the strong counterpart. Further, we present a new value of the jitter noise for this pulsar of 8.20 ± 0.14 ns in one hour, finding it to be consistent with previous measurements taken with the MeerKAT (9 ± 3 ns) and Parkes (8.6 ± 0.8 ns) telescopes, but inconsistent with the previously most precise measurement taken with the Green Bank telescope (14 ± 0.5 ns). Timing analysis on the individual modes is carried out for this pulsar, and we find an approximate |$10\, \mathrm{per\,cent}$| improvement in the timing precision is achievable through timing the strong mode only as opposed to the full sample of pulses. By forming a model of the average pulse from templates of the two modes, we time them simultaneously and demonstrate that this timing improvement can also be achieved in regular timing observations. We discuss the impact an improvement of this degree on this pulsar would have on searches for the stochastic gravitational wave background, as well as the impact of a similar improvement on all MeerTime PTA pulsars. [ABSTRACT FROM AUTHOR]

Published
2022
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36. The NANOGrav 12.5 yr Data Set: Polarimetry and Faraday Rotation Measures from Observations of Millisecond Pulsars with the Green Bank Telescope.

Author

Wahl, H. M., McLaughlin, M. A., Gentile, P. A., Jones, M. L., Spiewak, R., Arzoumanian, Z., Crowter, K., Demorest, P. B., DeCesar, M. E., Dolch, T., Ellis, J. A., Ferdman, R. D., Ferrara, E. C., Fonseca, E., Garver-Daniels, N., Jones, G., Lam, M. T., Levin, L., Lewandowska, N., and Lorimer, D. R.

Subjects
PULSARS, POLARIMETRY, MAGNETIC declination, GALACTIC magnetic fields, INTERSTELLAR medium, MUELLER calculus, MAGNETIC fields, TELESCOPES
Abstract

In this work, we present polarization profiles for 23 millisecond pulsars observed at 820 and 1500 MHz with the Green Bank Telescope as part of the NANOGrav pulsar timing array. We calibrate the data using Mueller matrix solutions calculated from observations of PSRs B1929+10 and J1022+1001. We discuss the polarization profiles, which can be used to constrain pulsar emission geometry, and present both the first published radio polarization profiles for nine pulsars and the discovery of very low-intensity average profile components ("microcomponents") in four pulsars. We obtain the Faraday rotation measures for each pulsar and use them to calculate the Galactic magnetic field parallel to the line of sight for different lines of sight through the interstellar medium. We fit for linear and sinusoidal trends in time in the dispersion measure and Galactic magnetic field and detect magnetic field variations with a period of 1 yr in some pulsars, but overall find that the variations in these parameters are more consistent with a stochastic origin. [ABSTRACT FROM AUTHOR]

Published
2022
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37. Thousand-Pulsar-Array programme on MeerKAT – VI. Pulse widths of a large and diverse sample of radio pulsars.

Author

Posselt, B, Karastergiou, A, Johnston, S, Parthasarathy, A, Keith, M J, Oswald, L S, Song, X, Weltevrede, P, Barr, E D, Buchner, S, Geyer, M, Kramer, M, Reardon, D J, Serylak, M, Shannon, R M, Spiewak, R, and Venkatraman Krishnan, V

Subjects
PULSARS, MEERKAT, WIDTH measurement, ACTINIC flux, RADIO measurements
Abstract

We present pulse width measurements for a sample of radio pulsars observed with the MeerKAT telescope as part of the Thousand-Pulsar-Array (TPA) programme in the MeerTime project. For a centre frequency of 1284 MHz, we obtain 762 W 10 measurements across the total bandwidth of 775 MHz, where W 10 is the width at the 10 per cent level of the pulse peak. We also measure about 400 W 10 values in each of the four or eight frequency sub-bands. Assuming, the width is a function of the rotation period P , this relationship can be described with a power law with power law index μ = −0.29 ± 0.03. However, using orthogonal distance regression, we determine a steeper power law with μ = −0.63 ± 0.06. A density plot of the period-width data reveals such a fit to align well with the contours of highest density. Building on a previous population synthesis model, we obtain population-based estimates of the obliquity of the magnetic axis with respect to the rotation axis for our pulsars. Investigating the width changes over frequency, we unambiguously identify a group of pulsars that have width broadening at higher frequencies. The measured width changes show a monotonic behaviour with frequency for the whole TPA pulsar population, whether the pulses are becoming narrower or broader with increasing frequency. We exclude a sensitivity bias, scattering and noticeable differences in the pulse component numbers as explanations for these width changes, and attempt an explanation using a qualitative model of five contributing Gaussian pulse components with flux density spectra that depend on their rotational phase. [ABSTRACT FROM AUTHOR]

Published
2021
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39. The Parkes pulsar timing array second data release: timing analysis.

Author

Reardon, D J, Shannon, R M, Cameron, A D, Goncharov, B, Hobbs, G B, Middleton, H, Shamohammadi, M, Thyagarajan, N, Bailes, M, Bhat, N D R, Dai, S, Kerr, M, Manchester, R N, Russell, C J, Spiewak, R, Wang, J B, and Zhu, X J

Subjects
BINARY pulsars, PULSARS, NEUTRON stars, INTERSTELLAR medium, STELLAR mass, GRAVITATIONAL waves
Abstract

The main goal of pulsar timing array experiments is to detect correlated signals such as nanohertz-frequency gravitational waves. Pulsar timing data collected in dense monitoring campaigns can also be used to study the stars themselves, their binary companions, and the intervening ionized interstellar medium. Timing observations are extraordinarily sensitive to changes in path-length between the pulsar and the Earth, enabling precise measurements of the pulsar positions, distances and velocities, and the shapes of their orbits. Here we present a timing analysis of 25 pulsars observed as part of the Parkes Pulsar Timing Array (PPTA) project over time spans of up to 24 yr. The data are from the second data release of the PPTA, which we have extended by including legacy data. We make the first detection of Shapiro delay in four Southern pulsars (PSRs J1017−7156, J1125−6014, J1545−4550, and J1732−5049), and of parallax in six pulsars. The prominent Shapiro delay of PSR J1125−6014 implies a neutron star mass of Mp = 1.5 ± 0.2 M⊙ (68 per cent credibility interval). Measurements of both Shapiro delay and relativistic periastron advance in PSR J1600−3053 yield a large but uncertain pulsar mass of |$M_p = 2.06^{+0.44}_{-0.41}$|  M⊙ (68 per cent credibility interval). We measure the distance to PSR J1909−3744 to a precision of 10 lyr, indicating that for gravitational wave periods over a decade, the pulsar provides a coherent baseline for pulsar timing array experiments. [ABSTRACT FROM AUTHOR]

Published
2021
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40. Clocking Stars with Radio Telescopes: Timing Four Pulsars from the GBNCC Survey

Author

Aloisi, R., Cruz, A., Daniels, L., Meyers, N., Roekle, R., Schuett, A., Swiggum, J., Decesar, M. E., Kaplan, D., Lynch, R. S., Stovall, K., Levin, L. S., Archibald, A., Banaszak, S., Chawla, P., Cui, B., Fonseca, E., Kaspi, V., Kondratiev, V., Mclaughlin, M., Al Noori, H., Ransom, S. M., Spiewak, R., Stairs, I., Leeuwen, J., Boyles, J., Hessels, J., Mallory Roberts, Karako-Argaman, C., Siemens, X., and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We present the timing solutions for four pulsars discovered in the Green Bank Northern Celestial Cap (GBNCC) survey. Timing observations were processed and timing solutions were obtained by undergraduate students participating in course-based research at the University of Wisconsin - Milwaukee. Both discovery and timing observations were conducted at a center frequency of 350 MHz using the 100-m Robert C. Byrd Green Bank Telescope. All four pulsars are isolated with spin periods between 0.26 s and 1.84 s. PSR J0038-2501 has a 0.26 s period and a period derivative of 7.6 × 10-19 s s-1, which is unusually low for isolated, longer period pulsars. This low period derivative may be simply an extreme value for an isolated pulsar or it could indicate an unusual evolution path for PSR J0038-2501, such as a disrupted recycled pulsar (DRP) from a binary system or an orphaned central compact object (CCO). Correcting the observed spin-down rate for the Shklovkii effect suggests that this pulsar may have an unusually low space velocity, which is consistent with expectations for DRPs since they come from disrupted binaries. There is no X-ray emission detected from PSR J0038-2501 in an archival Neil Gehrels Swift Observatory observation, which suggests that it is not a young orphaned CCO. A second pulsar, PSR J1949+3426 has a high dispersion measure suggesting that it is one of the most distant pulsars discovered in the GBNCC survey at an estimated distance of 12.3 kpc. Among the pulsars discovered in the GBNCC survey that makes it one of the brightest pulsars discovered in the GBNCC survey with a pseudo-luminosity of 570 mJy kpc2.

Published
2019

41. The Green Bank Northern Celestial Cap Pulsar Survey II: The Discovery and Timing of Ten Pulsars

Author

Kawash, A. M., McLaughlin, M. A., Kaplan, D. L., DeCesar, M. E., Levin, L., Lorimer, D. R., Lynch, R. S., Stovall, K., Swiggum, J. K., Fonseca, E., Archibald, A. M., Banaszak, S., Biwer, C. M., Boyles, J., Cui, B., Dartez, L. P., Day, D., Ernst, S., Ford, A. J., Flanigan, J., Heatherly, S. A., Hessels, J. W. T., Hinojosa, J., Jenet, F. A., Karako-Argaman, C., Kaspi, V. M., Kondratiev, V. I., Leake, S., Lunsford, G., Martinez, J. G., Mata, A., Matheny, T. D., Mcewen, A. E., Mingyar, M. G., Orsini, A. L., Ransom, S. M., Roberts, M. S. E., Rohr, M. D., Siemens, X., Spiewak, R., Stairs, I. H., van Leeuwen, J., Walker, A. N., and Wells, B. L.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics
Abstract

We present timing solutions for ten pulsars discovered in 350 MHz searches with the Green Bank Telescope. Nine of these were discovered in the Green Bank Northern Celestial Cap survey and one was discovered by students in the Pulsar Search Collaboratory program in analysis of drift-scan data. Following discovery and confirmation with the Green Bank Telescope, timing has yielded phase-connected solutions with high precision measurements of rotational and astrometric parameters. Eight of the pulsars are slow and isolated, including PSR J0930$-$2301, a pulsar with nulling fraction lower limit of $\sim$30\% and nulling timescale of seconds to minutes. This pulsar also shows evidence of mode changing. The remaining two pulsars have undergone recycling, accreting material from binary companions, resulting in higher spin frequencies. PSR J0557$-$2948 is an isolated, 44 \rm{ms} pulsar that has been partially recycled and is likely a former member of a binary system which was disrupted by a second supernova. The paucity of such so-called `disrupted binary pulsars' (DRPs) compared to double neutron star (DNS) binaries can be used to test current evolutionary scenarios, especially the kicks imparted on the neutron stars in the second supernova. There is some evidence that DRPs have larger space velocities, which could explain their small numbers. PSR J1806+2819 is a 15 \rm{ms} pulsar in a 44 day orbit with a low mass white dwarf companion. We did not detect the companion in archival optical data, indicating that it must be older than 1200 Myr., 9 pages, 5 figures

Published
2018

43. The Thousand-Pulsar-Array programme on MeerKAT – II. Observing strategy for pulsar monitoring with subarrays.

Author

Song, X, Weltevrede, P, Keith, M J, Johnston, S, Karastergiou, A, Bailes, M, Barr, E D, Buchner, S, Geyer, M, Hugo, B V, Jameson, A, Parthasarathy, A, Reardon, D J, Serylak, M, Shannon, R M, Spiewak, R, van Straten, W, and Venkatraman Krishnan, V

Subjects
PULSARS, MEERKAT, RADIO telescopes, VERY large array telescopes, TELESCOPES
Abstract

The Thousand-Pulsar-Array (TPA) programme currently monitors about 500 pulsars with the sensitive MeerKAT radio telescope by using subarrays to observe multiple sources simultaneously. Here we define the adopted observing strategy, which guarantees that each target is observed long enough to obtain a high-fidelity pulse profile, thereby reaching a sufficient precision of a simple pulse shape parameter. This precision is estimated from the contribution of the system noise of the telescope, and the pulse-to-pulse variability of each pulsar, which we quantify under some simplifying assumptions. We test the assumptions and choice of model parameters using data from the MeerKAT 64-dish array and the Lovell and Parkes telescopes. We demonstrate that the observing times derived from our method produce high-fidelity pulse profiles that meet the needs of the TPA in studying pulse shape variability and pulsar timing. Our method can also be used to compare strategies for observing large numbers of pulsars with telescopes capable of forming multiple subarray configurations. We find that using two 32-dish MeerKAT subarrays is the most efficient strategy for the TPA project. We also find that the ability to observe in different array configurations will become increasingly important for large observing programmes using the Square Kilometre Array telescope. [ABSTRACT FROM AUTHOR]

Published
2021
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44. The thousand-pulsar-array programme on MeerKAT IV: Polarization properties of young, energetic pulsars.

Author

Serylak, M, Johnston, S, Kramer, M, Buchner, S, Karastergiou, A, Keith, M J, Parthasarathy, A, Weltevrede, P, Bailes, M, Barr, E D, Camilo, F, Geyer, M, Hugo, B V, Jameson, A, Reardon, D J, Shannon, R M, Spiewak, R, van Straten, W, and Venkatraman Krishnan, V

Subjects
PULSARS, MEERKAT, BINARY pulsars, TELESCOPES, GEOMETRY, INTERFEROMETERS
Abstract

We present observations of 35 high spin-down energy radio pulsars using the MeerKAT telescope. Polarization profiles and associated parameters are also presented. We derive the geometry for a selection of pulsars which show interpulse emission. We point out that, in several cases, these radio pulsars should also be seen in γ-rays but that improved radio timing is required to aid the high-energy detection. We discuss the relationship between the width of the radio profile and its high-energy detectability. Finally, we reflect on the correlation between the spin-down energy and the radio polarization fraction and the implications this may have for γ-ray emission. [ABSTRACT FROM AUTHOR]

Published
2021
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45. Measurements of pulse jitter and single-pulse variability in millisecond pulsars using MeerKAT.

Author

Parthasarathy, A, Bailes, M, Shannon, R M, van Straten, W, Osłowski, S, Johnston, S, Spiewak, R, Reardon, D J, Kramer, M, Venkatraman Krishnan, V, Pennucci, T T, Abbate, F, Buchner, S, Camilo, F, Champion, D J, Geyer, M, Hugo, B, Jameson, A, Karastergiou, A, and Keith, M J

Subjects
PULSARS, MEERKAT, RADIO telescopes, SIGNAL-to-noise ratio
Abstract

Using the state-of-the-art SKA precursor, the MeerKAT radio telescope, we explore the limits to precision pulsar timing of millisecond pulsars achievable due to pulse stochasticity (jitter). We report new jitter measurements in 15 of the 29 pulsars in our sample and find that the levels of jitter can vary dramatically between them. For some, like the 2.2 ms pulsar PSR J2241−5236, we measure an implied jitter of just ∼4 ns h−1, while others, like the 3.9 ms PSR J0636−3044, are limited to ∼100 ns h−1. While it is well known that jitter plays a central role to limiting the precision measurements of arrival times for high signal-to-noise ratio observations, its role in the measurement of dispersion measure (DM) has not been reported, particularly in broad-band observations. Using the exceptional sensitivity of MeerKAT, we explored this on the bright millisecond pulsar PSR J0437−4715 by exploring the DM of literally every pulse. We found that the derived single-pulse DMs vary by typically 0.0085 cm−3 pc from the mean, and that the best DM estimate is limited by the differential pulse jitter across the band. We postulate that all millisecond pulsars will have their own limit on DM precision which can only be overcome with longer integrations. Using high-time resolution filterbank data of 9 μs, we also present a statistical analysis of single-pulse phenomenology. Finally, we discuss optimization strategies for the MeerKAT pulsar timing program and its role in the context of the International Pulsar Timing Array. [ABSTRACT FROM AUTHOR]

Published
2021
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46. Identifying and mitigating noise sources in precision pulsar timing data sets.

Author

Goncharov, Boris, Reardon, D J, Shannon, R M, Zhu, Xing-Jiang, Thrane, Eric, Bailes, M, Bhat, N D R, Dai, S, Hobbs, G, Kerr, M, Manchester, R N, Osłowski, S, Parthasarathy, A, Russell, C J, Spiewak, R, Thyagarajan, N, and Wang, J B

Subjects
PULSARS, GRAVITATIONAL waves, NOISE, STATISTICAL models
Abstract

Pulsar timing array projects measure the pulse arrival times of millisecond pulsars for the primary purpose of detecting nanohertz-frequency gravitational waves. The measurements include contributions from a number of astrophysical and instrumental processes, which can either be deterministic or stochastic. It is necessary to develop robust statistical and physical models for these noise processes because incorrect models diminish sensitivity and may cause a spurious gravitational wave detection. Here we characterize noise processes for the 26 pulsars in the second data release of the Parkes Pulsar Timing Array using Bayesian inference. In addition to well-studied noise sources found previously in pulsar timing array data sets such as achromatic timing noise and dispersion measure variations, we identify new noise sources including time-correlated chromatic noise that we attribute to variations in pulse scattering. We also identify 'exponential dip' events in four pulsars, which we attribute to magnetospheric effects as evidenced by pulse profile shape changes observed for three of the pulsars. This includes an event in PSR J1713+0747, which had previously been attributed to interstellar propagation. We present noise models to be used in searches for gravitational waves. We outline a robust methodology to evaluate the performance of noise models and identify unknown signals in the data. The detection of variations in pulse profiles highlights the need to develop efficient profile domain timing methods. [ABSTRACT FROM AUTHOR]

Published
2021
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47. Searching for gravitational-wave bursts from cosmic string cusps with the Parkes Pulsar Timing Array.

Author

Yonemaru, N, Kuroyanagi, S, Hobbs, G, Takahashi, K, Zhu, X-J, Coles, W A, Dai, S, Howard, E, Manchester, R, Reardon, D, Russell, C, M Shannon, R, Thyagarajan, N, Spiewak, R, and Wang, J-B

Subjects
COSMIC strings, PULSARS, FALSE alarms, GRAVITATIONAL waves
Abstract

Cosmic strings are potential gravitational-wave (GW) sources that can be probed by pulsar timing arrays (PTAs). In this work we develop a detection algorithm for a GW burst from a cusp on a cosmic string, and apply it to Parkes PTA data. We find four events with a false alarm probability less than 1 per cent. However further investigation shows that all of these are likely to be spurious. As there are no convincing detections we place upper limits on the GW amplitude for different event durations. From these bounds we place limits on the cosmic string tension of G μ ∼ 10−5, and highlight that this bound is independent from those obtained using other techniques. We discuss the physical implications of our results and the prospect of probing cosmic strings in the era of Square Kilometre Array. [ABSTRACT FROM AUTHOR]

Published
2021
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48. Giant pulses from J1823−3021A observed with the MeerKAT telescope.

Author

Abbate, F, Bailes, M, Buchner, S J, Camilo, F, Freire, P C C, Geyer, M, Jameson, A, Kramer, M, Possenti, A, Ridolfi, A, Serylak, M, Spiewak, R, Stappers, B W, and Venkatraman Krishnan, V

Subjects
MEERKAT, LINEAR polarization, RADIO telescopes, CIRCULAR polarization, TELESCOPES, GLOBULAR clusters
Abstract

The millisecond pulsar J1823−3021A is a very active giant pulse emitter in the globular cluster NGC 6624. New observations with the MeerKAT radio telescope have revealed 14350 giant pulses over 5 h of integration time, with an average wait time of about 1 s between giant pulses. The giant pulses occur in phases compatible with the ordinary radio emission, follow a power-law distribution with an index of −2.63 ± 0.02, and contribute 4 per cent of the total integrated flux. The spectral index of the giant pulses follows a Gaussian distribution centred around −1.9 with a standard deviation of 0.6 and is on average flatter than the integrated emission, which has a spectral index of −2.81 ± 0.02. The waiting times between the GPs are accurately described by a Poissonian distribution, suggesting that the time of occurrence of a GP is independent from the times of occurrence of other GPs. 76 GPs show multiple peaks within the same rotation, a rate that is also compatible with the mutual independence of the GP times of occurrence. We studied the polarization properties of the giant pulses finding, on average, linear polarization only at the 1 per cent level and circular polarization at the 3 per cent level, similar to the polarization percentages of the total integrated emission. In four cases, it was possible to measure the RM of the GPs that are highly variable and, in two cases, is inconsistent with the mean RM of the total integrated pulsar signal. [ABSTRACT FROM AUTHOR]

Published
2020
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49. Which bright fast radio bursts repeat?

Author

James, C W, Osłowski, S, Flynn, C, Kumar, P, Bannister, K, Bhandari, S, Farah, W, Kerr, M, Lorimer, D R, Macquart, J-P, Ng, C, Phillips, C, Price, D C, Qiu, H, Shannon, R M, and Spiewak, R

Subjects
CONFIDENCE intervals, RADIOS
Abstract

A handful of fast radio bursts (FRBs) are now known to repeat. However, the question remains – do they all? We report on an extensive observational campaign with the Australian Square Kilometre Array Pathfinder (ASKAP), Parkes, and Robert C. Byrd Green Bank Telescope, searching for repeat bursts from FRBs detected by the Commensal Real-time ASKAP Fast Transients survey. In 383.2 h of follow-up observations covering 27 FRBs initially detected as single bursts, only two repeat bursts from a single FRB, FRB 171019, were detected, which have been previously reported by Kumar et al. We use simulations of repeating FRBs that allow for clustering in burst arrival times to calculate new estimates for the repetition rate of FRB 171019, finding only slight evidence for incompatibility with the properties of FRB 121102. Our lack of repeat bursts from the remaining FRBs set limits on the model of all bursts being attributable to repeating FRBs. Assuming a reasonable range of repetition behaviour, at most 60 per cent (90 per cent confidence limit) of these FRBs have an intrinsic burst distribution similar to FRB 121102. This result is shown to be robust against different assumptions on the nature of repeating FRB behaviour, and indicates that if indeed all FRBs repeat, the majority must do so very rarely. [ABSTRACT FROM AUTHOR]

Published
2020
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