Timing irregularities and glitches from the pulsar monitoring campaign at IAR

Abstract

Context. Pulsars have an overall very stable rotation. However, sudden increases in their rotation frequency, known as glitches, perturbtheir evolution. While many observatories commonly detect large glitches, small glitches are harder to detect because of the lack ofdaily-cadence observations over long periods of time (years).Aims. We aim to explore and characterise the timing behaviour of young pulsars at daily timescales, looking for small glitches andother irregularities. The results will further our comprehension of the real distribution of glitch sizes, which has also consequences forthe theoretical modeling of the glitch mechanism.Methods. We observed six pulsars with up to daily cadence between December 2019 and January 2024 with the two antennas of theArgentine Institute of Radio Astronomy (IAR). We used standard pulsar timing tools to obtain the times of arrival of the pulses andto characterise the pulsar’s rotation. We developed an algorithm to look for small timing events in the data and calculate the changesin the frequency (ν) and its derivative (˙ν) at those epochs.Results. We found that the rotation of all pulsars in this dataset is affected by small step changes in ν and ˙ν. Among them, we foundthree new glitches that had not been reported before: two glitches in PSR J1048−5832 with relative sizes ∆ν/ν = 9.1(4) × 10−10 and∆ν/ν = 4.5(1) × 10−9, and one glitch in the Vela pulsar with a size ∆ν/ν = 2.0(2) × 10−10. We also report new decay terms on the 2021Vela giant glitch, and on the 2022 giant glitches in PSR J0742−2822 and PSR J1740−3015 respectively. In addition, we found thatthe red noise contribution significantly diminished in PSR J0742−2822 after its giant glitch in 2022.Conclusions. Our results highlight the importance of high-cadence monitoring with an exhaustive analysis of the residuals to bettercharacterize the distribution of glitch sizes and to deepen our understanding of the mechanisms behind glitches, red noise and timingirregularities.