Radio and gamma-ray timing of TRAPUM L-band Fermi pulsar survey discoveries

TL;DR

This study combines radio and gamma-ray observations to precisely time nine MSPs discovered by the TRAPUM survey, revealing detailed binary and pulsar parameters and demonstrating the effectiveness of joint timing analysis.

Contribution

It introduces a new joint radio and gamma-ray timing method using MCMC, enabling precise measurement of pulsar parameters, including proper motions, for the first time in some cases.

Findings

Six pulsars show gamma-ray pulsations.

Proper motions measured for four pulsars.

Joint analysis improves parameter precision.

Abstract

This paper presents the results of a joint radio and gamma-ray timing campaign on the nine millisecond pulsars (MSPs) discovered as part of the L-band targeted survey of Fermi-LAT sources performed in the context of the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. Out of these pulsars, eight are members of binary systems; of these eight, two exhibit extended eclipses of the radio emission. Using an initial radio timing solution, pulsations were found in the gamma rays for six of the targets. For these sources, a joint timing analysis of radio times of arrival and gamma-ray photons was performed, using a newly developed code that optimises the parameters through a Markov chain Monte Carlo (MCMC) technique. This approach has allowed us to precisely measure both the short- and long-term timing parameters. This study includes a proper motion measurement for four pulsars, which a gamma ray-only analysis would not have been sensitive to, despite the 15-year span of Fermi data.