Improving pulsar timing precision through superior time-of-arrival creation

¹ Ruhr-Universität Bochum, Fakultät für Physik und Astronomie, Astronomisches Institut (AIRUB), 44801 Bochum, Germany
e-mail: jun.wang.ucas@gmail.com
² Advanced Institute of Natural Sciences, Beijing Normal University, Zhuhai 519087, PR China
³ Fakulatät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
⁴ Florida Space Institute, University of Central Florida, 12354 Research Parkway, Orlando, FL 32826, USA
⁵ Dipartimento di Fisica ‘G. Occhialini’, Università degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
⁶ INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
⁷ Laboratoire de Physique et Chimie de l’Environnement et de l’Espace LPC2E CNRS-Université d’Orléans, 45071 Orléans, France
⁸ Station de radioastronomie de Nançay, Observatoire de Paris, PSL Research University, CNRS/INSU, 18330 Nançay, France
⁹ ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
¹⁰ Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
¹¹ Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL, UK
¹² INAF – Osservatorio Astronomico di Cagliari, via della Scienza 5, 09047 Selargius (CA), Italy
¹³ Laboratoire Univers et Théories LUTh, Observatoire de Paris, PSL Research University, CNRS/INSU, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France

Received: 27 January 2024
Accepted: 13 May 2024

Abstract

Context. The measurement of pulsar pulse times-of-arrival (ToAs) is a crucial step in detecting low-frequency gravitational waves. To determine ToAs, we can use template-matching to compare each observed pulse profile with a standard template. However, using different combinations of templates and template-matching methods (TMMs) without careful consideration can lead to inconsistent results.

Aims. In pulsar timing array (PTA) experiments, distinct ToAs from the same observations can be obtained due to the use of diverse templates and TMMs. In other words, employing diverse approaches can yield different timing results and would thus have a significant impact on subsequent gravitational wave searches. In this paper we examine several commonly used combinations to analyze their effect on pulse ToAs.

Methods. We evaluated the potential impact of template and TMM selection on 13 typical millisecond pulsars within the European PTA. We employed pulsar timing methods, specifically the root mean square and reduced chi-square (χ²_r) of the residuals of the best timing solution, to assess the outcomes. Additionally, we evaluated the system-limited noise floor (SLNF) for each pulsar at various telescopes operating around 1.4 GHz using frequency-resolved templates.

Results. Our findings suggest that utilizing data-derived and smoothed templates in conjunction with the Fourier-domain with Markov chain Monte Carlo TMM is generally the most effective approach, though there may be exceptions that require further attention. Furthermore, we determine that pulse phase jitter noise does not significantly limit the current precision of the European PTA’s timing, as jitter levels derived from other studies are much lower than the SLNF.