The MeerKAT Pulsar Timing Array: the first search for gravitational waves with the MeerKAT radio telescope

ABSTRACT Pulsar timing arrays search for nanohertz-frequency gravitational waves by regularly observing ensembles of millisecond pulsars over many years to look for correlated timing residuals. Recently the first evidence for a stochastic gravitational wave background has been presented by the major arrays, with varying levels of significance (${\sim} 2\sigma \!-\! 4\sigma$). In this paper, we present the results of background searches with the MeerKAT Pulsar Timing Array. Although of limited duration (4.5 yr), the ${\sim} 250\,000$ arrival times with a median error of just $3 \, \mu {\rm s}$ on 83 pulsars make it very sensitive to spatial correlations. Detection of a gravitational wave background requires careful modelling of noise processes to ensure that any correlations represent a fit to the underlying background and not other misspecified processes. Under different assumptions about noise processes, we can produce either what appear to be compelling Hellings–Downs correlations of high significance ($3\sigma \!-\! 3.4\sigma$) with a spectrum close to that which is predicted, or surprisingly, under slightly different assumptions, ones that are insignificant. This appears to be related to the fact that many of the highest precision MeerKAT Pulsar Timing Array pulsars are in close proximity and dominate the detection statistics. The sky-averaged characteristic strain amplitude of the correlated signal in our most significant model is $h_{{\rm c}, {\rm yr}} = 7.5^{+0.8}_{-0.9} \times 10^{-15}$ measured at a spectral index of $\alpha =-0.26$, decreasing to $h_{{\rm c}, {\rm yr}} = 4.8^{+0.8}_{-0.9} \times 10^{-15}$ when assessed at the predicted $\alpha =-2/3$. These data will be valuable as the International Pulsar Timing Array project explores the significance of gravitational wave detections and their dependence on the assumed noise models.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-12-03
DOI
https://doi.org/10.1093/mnras/stae2571
Citations
62
Primary Topic
Pulsars and Gravitational Waves Research
Type
article
Field-Weighted Citation Impact
20.55

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article

The MeerKAT Pulsar Timing Array: the first search for gravitational waves with the MeerKAT radio telescope

Jaikhomba Singha, Sarah Buchner, M. Krämer, D. J. Champion et al.
62 citations
Monthly Notices of the Royal Astronomical Society
Pulsars and Gravitational Waves Research
20.55
article

The MeerKAT Pulsar Timing Array: the first search for gravitational waves with the MeerKAT radio telescope

Jaikhomba Singha, Sarah Buchner, M. Krämer, D. J. Champion, Kathrin Grunthal, Rowina S Nathan, R. M. Shannon, F. Camilo, Andrea Possenti, Daniel J. Reardon, A. Parthasarathy, Atharva Kulkarni, G. Shaifullah, Mohsen Shamohammadi, Marisa Geyer, Federico Abbate, V. Venkatraman Krishnan, A D Cameron, M. J. Keith, M. Bailes, G. Theureau, E. Thrane, Matthew T. Miles, Pratyasha Gitika, Beatrice E Moreschi
article en
62 citations

Abstract

ABSTRACT Pulsar timing arrays search for nanohertz-frequency gravitational waves by regularly observing ensembles of millisecond pulsars over many years to look for correlated timing residuals. Recently the first evidence for a stochastic gravitational wave background has been presented by the major arrays, with varying levels of significance (${\sim} 2\sigma \!-\! 4\sigma$). In this paper, we present the results of background searches with the MeerKAT Pulsar Timing Array. Although of limited duration (4.5 yr), the ${\sim} 250\,000$ arrival times with a median error of just $3 \, \mu {\rm s}$ on 83 pulsars make it very sensitive to spatial correlations. Detection of a gravitational wave background requires careful modelling of noise processes to ensure that any correlations represent a fit to the underlying background and not other misspecified processes. Under different assumptions about noise processes, we can produce either what appear to be compelling Hellings–Downs correlations of high significance ($3\sigma \!-\! 3.4\sigma$) with a spectrum close to that which is predicted, or surprisingly, under slightly different assumptions, ones that are insignificant. This appears to be related to the fact that many of the highest precision MeerKAT Pulsar Timing Array pulsars are in close proximity and dominate the detection statistics. The sky-averaged characteristic strain amplitude of the correlated signal in our most significant model is $h_{{\rm c}, {\rm yr}} = 7.5^{+0.8}_{-0.9} \times 10^{-15}$ measured at a spectral index of $\alpha =-0.26$, decreasing to $h_{{\rm c}, {\rm yr}} = 4.8^{+0.8}_{-0.9} \times 10^{-15}$ when assessed at the predicted $\alpha =-2/3$. These data will be valuable as the International Pulsar Timing Array project explores the significance of gravitational wave detections and their dependence on the assumed noise models.

Monthly Notices of the Royal Astronomical SocietyVol. 536(2)
Université d'Orléans (FR), Centre National de la Recherche Scientifique (FR), University of Cape Town (ZA), Université Paris Cité (FR), Université Paris Sciences et Lettres (FR), University of Manchester (GB), Laboratoire Univers et Théories (FR), South African Radio Astronomy Observatory (ZA), ARC Centre of Excellence for Gravitational Wave Discovery (AU), Astronomical Institute of the Slovak Academy of Sciences (SK), Osservatorio Astronomico di Cagliari (IT), Max Planck Institute for Radio Astronomy (DE), Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (FR), Monash University (AU), Swinburne University of Technology (AU), University of Milano-Bicocca (IT), University of Amsterdam (NL), Netherlands Institute for Radio Astronomy (NL)
Department of Science and Innovation, South Africa, International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, National Research Foundation, Agence Nationale de la Recherche, Swinburne University of Technology, Centre National d’Etudes Spatiales, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Max-Planck-Gesellschaft, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, International Max Planck Research School for Advanced Methods in Process and Systems Engineering, Observatoire de Paris, Université de Recherche Paris Sciences et Lettres, Science and Technology Facilities Council, Australian Research Council, Institut national des sciences de l'Univers, Institut National de Physique Nucléaire et de Physique des Particules, Institut de physique, H2020 European Research Council
Openalex Percentile: Top 0%
Pulsars and Gravitational Waves Research
20.55
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