The LOFAR Tied-Array All-Sky Survey: Timing of 35 radio pulsars and an overview of the properties of the LOFAR pulsar discoveries

¹ ASTRON, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
e-mail: emma.vanderwateren@gmail.com
² Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010 6500 GL Nijmegen, The Netherlands
³ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
⁴ LPC2E – Université d’Orléans/CNRS, 3A avenue de la Recherche Scientifique, 45071 Orléans, France
⁵ ORN, Observatoire de Paris, Université PSL, Univ. Orléans, CNRS, 18330 Nançay, France
⁶ Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
⁷ Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
⁸ MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
⁹ Department of Physics, McGill University, 3600 Rue University, Montréal, QC H3A 2T8, Canada
¹⁰ McGill Space Institute, McGill University, 3550 Rue University, Montréal, QC H3A 2A7, Canada
¹¹ INAF – Cagliari Astronomical Observatory, Via della Scienza 5, 09047 Selargius, CA, Italy
¹² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹³ Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
¹⁴ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
¹⁵ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
¹⁶ Ruhr University Bochum, Faculty of Physics and Astronomy, Astronomical Institute, 44780 Bochum, Germany
¹⁷ Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
¹⁸ Manly Astrophysics, 15/41-42 East Esplanade, Manly, NSW 2095, Australia
¹⁹ SKA Observatory, Jodrell Bank, Lower Withington, Macclesfield SK11 9FT, UK
²⁰ Department of Physics and Astronomy, University of the Western Cape, Bellville, Cape Town 7535, South Africa
²¹ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany

Received: 3 October 2022
Accepted: 18 November 2022

Abstract

The LOFAR Tied-Array All-Sky Survey (LOTAAS) is the most sensitive untargeted radio pulsar survey performed at low radio frequencies (119−151 MHz) to date and has discovered 76 new radio pulsars, including the 23.5-s pulsar J0250+5854, which up until recently was the slowest spinning radio pulsar known. In this paper, we report on the timing solutions of 35 pulsars discovered by LOTAAS, which include a nulling pulsar and a mildly recycled pulsar, and thereby complete the full timing analysis of the LOTAAS pulsar discoveries. We give an overview of the findings from the full LOTAAS sample of 76 pulsars, discussing their pulse profiles, radio spectra, and timing parameters. We found that the pulse profiles of some of the pulsars show profile variations in time or frequency, and while some pulsars show signs of scattering, a large majority display no pulse broadening. The LOTAAS discoveries have on average steeper radio spectra and longer spin periods (1.4×), as well as lower spin-down rates (3.1×) compared to the known pulsar population. We discuss the cause of these differences and attribute them to a combination of selection effects of the LOTAAS survey as well as previous pulsar surveys, though we cannot rule out that older pulsars tend to have steeper radio spectra.