Timing observations of three Galactic millisecond pulsars

• Published in: Monthly notices of the Royal Astronomical Society Vol. 507; no. 4; pp. 5303 - 5309
• Main Authors: Lorimer, D R, Kawash, A M, Freire, P C C, Smith, D A, Kerr, M, McLaughlin, M A, Mickaliger, M B, Spiewak, R, Bailes, M, Barr, E, Burgay, M, Cameron, A D, Camilo, F, Johnston, S, Jankowski, F, Keane, E F, Keith, M, Kramer, M, Possenti, A
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.11.2021
• Subjects: pulsars: individual (PSR J0921–5202, PSR J1146–6610, PSR J1546–5925); stars: neutron
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stab2474

ABSTRACT We report observed and derived timing parameters for three millisecond pulsars (MSPs) from observations collected with the Parkes 64-m telescope, Murriyang. The pulsars were found during reprocessing of archival survey data by Mickaliger et al. One of the new pulsars (PSR J1546–5925) has a spin period P = 7.8 ms and is isolated. The other two (PSR J0921–5202 with P = 9.7 ms and PSR J1146–6610 with P = 3.7 ms) are in binary systems around low-mass (${\gt}0.2\, {\rm M}_{\odot }$) companions. Their respective orbital periods are 38.2 and 62.8 d. While PSR J0921–5202 has a low orbital eccentricity e = 1.3 × 10−5, in keeping with many other Galactic MSPs, PSR J1146–6610 has a significantly larger eccentricity, e = 7.4 × 10−3. This makes it a likely member of a group of eccentric MSP–helium white dwarf binary systems in the Galactic disc whose formation is poorly understood. Two of the pulsars are co-located with previously unidentified point sources discovered with the Fermi satellite’s Large Area Telescope, but no γ-ray pulsations have been detected, likely due to their low spin-down powers. We also show that, particularly in terms of orbital diversity, the current sample of MSPs is far from complete and is subject to a number of selection biases.