The second data release from the European Pulsar Timing Array

I. The dataset and timing analysis

¹ Institute of Astrophysics, FORTH, N. Plastira 100, 70013 Heraklion, Greece
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
³ Université Paris Cité, CNRS, Astroparticule et Cosmologie, 75013 Paris, France
⁴ Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
⁵ ASTRON, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD, Dwingeloo, The Netherlands
⁶ Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, Université d’Orléans / CNRS, 45071 Orléans Cedex 02, France
⁷ Observatoire Radioastronomique de Nançay, Observatoire de Paris, Université PSL, Université d’Orléans, CNRS, 18330 Nançay, France
⁸ Dipartimento di Fisica “G. Occhialini”, Universitá degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
⁹ INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
¹⁰ INAF – Osservatorio Astronomico di Brera, via Brera 20, 20121 Milano, Italy
¹¹ Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
¹² INAF – Osservatorio Astronomico di Cagliari, via della Scienza 5, 09047 Selargius (CA), Italy
¹³ Hellenic Open University, School of Science and Technology, 26335 Patras, Greece
¹⁴ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
¹⁵ School of Physics, Faculty of Science, University of East Anglia, Norwich NR4 7TJ, UK
¹⁶ Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Muühlenberg 1, 14476 Potsdam, Germany
¹⁷ Gran Sasso Science Institute (GSSI), 67100 L’Aquila, Italy
¹⁸ INFN, Laboratori Nazionali del Gran Sasso, I67100 Assergi, Italy
¹⁹ Universitá di Cagliari, Dipartimento di Fisica, S.P. Monserrato-Sestu Km 0,700, 09042 Monserrato (CA), Italy
²⁰ Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
²¹ School of Physics, Trinity College Dublin, College Green, Dublin 2, D02 PN40, Ireland
²² Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
²³ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, PR China
²⁴ E.A. Milne Centre for Astrophysics, University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, UK
²⁵ Centre of Excellence for Data Science, Artificial Intelligence and Modelling (DAIM), University of Hull, Cottingham Road, Kingstonupon-Hull, HU6 7RX, UK
²⁶ Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612, USA
²⁷ IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
²⁸ Institut für Physik und Astronomie, Universität Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany
²⁹ Ollscoil na Gaillimhe – University of Galway, University Road, Galway H91 TK33, Ireland
³⁰ Laboratoire Univers et Théories LUTh, Observatoire de Paris, Université PSL, CNRS, Université de Paris, 92190 Meudon, France
³¹ Florida Space Institute, University of Central Florida, 12354 Research Parkway, Partnership 1 Building, Suite 214, Orlando, FL 32826-0650, USA
³² Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute (AIRUB), 44780 Bochum, Germany
³³ Advanced Institute of Natural Sciences, Beijing Normal University, Zhuhai 519087, PR China

Received: 8 May 2023
Accepted: 15 June 2023

Abstract

Pulsar timing arrays offer a probe of the low-frequency gravitational wave spectrum (1–100 nHz), which is intimately connected to a number of markers that can uniquely trace the formation and evolution of the Universe. We present the dataset and the results of the timing analysis from the second data release of the European Pulsar Timing Array (EPTA). The dataset contains high-precision pulsar timing data from 25 millisecond pulsars collected with the five largest radio telescopes in Europe, as well as the Large European Array for Pulsars. The dataset forms the foundation for the search for gravitational waves by the EPTA, presented in associated papers. We describe the dataset and present the results of the frequentist and Bayesian pulsar timing analysis for individual millisecond pulsars that have been observed over the last ~25 yr. We discuss the improvements to the individual pulsar parameter estimates, as well as new measurements of the physical properties of these pulsars and their companions. This data release extends the dataset from EPTA Data Release 1 up to the beginning of 2021, with individual pulsar datasets with timespans ranging from 14 to 25 yr. These lead to improved constraints on annual parallaxes, secular variation of the orbital period, and Shapiro delay for a number of sources. Based on these results, we derived astrophysical parameters that include distances, transverse velocities, binary pulsar masses, and annual orbital parallaxes.