Abstract :
Pulsars have attracted increasing interest over the past years as more data and more observing programmes become available. Binary pulsars in particular have proved valuable as the orbital motion gives access to the masses of both components and through the relativistic corrections to that motion, to tests of gravity that cannot be carried out elsewhere. PSR J1012+5307 is one such system, a millisecond pulsar with a helium core white dwarf companion that has been observed for nearly three decades. In this work we present a timing analysis of 25,080 times of arrival spanning 28.3 years from the third EPTA data release, fitting the timing and noise parameters jointly and sampling the Shapiro delay parameters, the orbital period derivative and the parallax explicitly whilst marginalising analytically over the remaining timing parameters. We perform the analysis twice, once imposing a prior on the parallax from the published VLBI measurement and once with no prior at all. In the latter case we obtain ϖ = 1.1457 ± 0.1448 mas that is in agreement with the VLBI value. Restricting the companion mass to the range adopted by the second EPTA data release gives mc = 0.202 (+0.061/−0.045) M☉, and combining this with the optical mass ratio gives a pulsar mass of mp = 2.11 (+0.64/−0.47) M☉, both consistent with the values determined from optical spectroscopy of the white dwarf. After removing the Shklovskii and Galactic contributions we measure an intrinsic orbital period derivative of Ṗb,int = −1.150 (+0.112/−0.121) × 10⁻¹⁴ that consistent with the value of −1.154 (+0.124/−0.129) × 10⁻¹⁴ predicted by general relativity with a ratio of measured to predicted decay of 0.997 ± 0.149.
