The Parkes pulsar timing array second data release: timing analysis

Abstract

The main goal of pulsar timing array experiments is to detect correlated signals such as nanohertz-frequency gravitational waves. Pulsar timing data collected in dense monitoring campaigns can also be used to study the stars themselves, their binary companions, and the intervening ionised interstellar medium. Timing observations are extraordinarily sensitive to changes in path-length between the pulsar and the Earth, enabling precise measurements of the pulsar positions, distances and velocities, and the shapes of their orbits. Here we present a timing analysis of 25 pulsars observed as part of the Parkes Pulsar Timing Array (PPTA) project over time spans of up to 24 yr. The data are from the second data release of the PPTA, which we have extended by including legacy data. We make the first detection of Shapiro delay in four Southern pulsars (PSRs J1017−7156, J1125−6014, J1545−4550, and J1732−5049), and of parallax in six pulsars. The prominent Shapiro delay of PSR J1125−6014 implies a neutron star mass of Mp = 1.5 ± 0.2M⊙ (68 per cent credibility interval). Measurements of both Shapiro delay and relativistic periastron advance in PSR J1600−3053 yield a large but uncertain pulsar mass of $M_p = 2.06^{+0.44}_{-0.41}$ M⊙ (68 per cent credibility interval). We measure the distance to PSR J1909−3744 to a precision of 10 lyr, indicating that for gravitational wave periods over a decade, the pulsar provides a coherent baseline for pulsar timing array experiments.

GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo During the Second Part of the Third Observing Run

“…These results are consistent with previous inferences [8], showing that the change in how the fast scattering glitches in Livingston data were mitigated (discussed in Appendix C) does not have a significant impact on this analysis. The primary is consistent with being a low-mass BH [8], we infer a 29% probability that m 1 < 5M ; the secondary is consistent with the masses of known Galactic NSs [159,[228][229][230]. GW200105 162426's source corresponds to a higher mass NSBH candidate, with M = 11.0 +1.5 −1.4 M , and M = 3.42 +0.08 −0.08 M .…”

Modelling annual scintillation arc variations in PSR J1643-1224 using the Large European Array for Pulsars

“…As can be seen in Figures B1 and B2, we observe strong degeneracies between pulsar distance 𝑑 psr and screen parameters, so obtaining accurate measurements is highly dependent on the accuracy of the priors on distance. As there has been slight tension between PTA measurements, with the previous IPTA value appearing lower (Verbiest et al 2016), and the recent PPTA value appearing higher (Reardon et al 2021) than the EPTA value (Desvignes et al 2016), we adopted a conservative distance prior, as described in Section 5.…”

Mode changing in J1909$-$3744: the most precisely timed pulsar

“…Similar campaigns to the one undertaken in this study may result in valuable insights into millisecond pulsars emission structures, and offer opportunities to gain greater timing precision. In precision timing studies of millisecond pulsars, PSR J1909−3744 is consistently one of the most precisely timed (Liu et al 2020;Alam et al 2021;Reardon et al 2021), with sub-microsecond root mean square (rms) timing residuals often achieved. This precision leads it to be one of the most important pulsars in the search for the SGWB, with publications (Arzoumanian et al 2020;Goncharov et al 2021) suggesting it is the first (NANOGrav) and third (PPTA) largest contributors to the detection efforts.…”