First results from the UTMOST-NS pulsar timing programme

Résumé fourni par la source

ABSTRACT The UTMOST-NS pulsar timing programme operated at the Molonglo Observatory Synthesis Telescope from 2021 April to 2023 June, observing 173 pulsars with an average cadence of 50 pulsars per day. An overview of the programme is presented, detailing the hardware, software, and observing strategy. Pulsar timing results are discussed, focusing on timing noise and glitches. It is shown that the scaling of residuals due to timing noise with pulsar parameters and observing time span is consistent with earlier studies, and that the recovered timing noise parameters remain consistent as the observing time span is increased. Second frequency derivatives are investigated, and it is shown that the uncertainty on $\ddot{\nu }$ is sensitive to the frequency cut-off in the timing noise model, varying by threefold approximately depending on whether Fourier modes with frequency lower than the reciprocal of the observing time span are included. We measure 39 non-zero values of $\ddot{\nu }$ when considering both models with and without low-frequency modes. An analytic scaling relating anomalous braking indices to timing noise amplitude is also validated. Glitches in the sample are discussed, including three detected by an ‘online’ glitch detection pipeline using a hidden Markov model (HMM). In total 17 glitches are discussed, one of which, in PSR J1902$+$0615, has not been reported elsewhere. An ‘offline’ glitch search pipeline using the HMM framework is used to search for previously undetected glitches. Systematic upper limits are set on the size of undetected glitches. The mean upper limit is $\Delta \nu ^{90\,{{\%}}}\!/\nu = 6.3 \times 10^{-9}$ at 90 per cent confidence.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.