Glitches in southern pulsars

Abstract

Timing observations of 40 mostly young pulsars using the ATNF Parkes radio telescope between 1990 January and 1998 December are reported. In total, 20 previously unreported glitches and ten other glitches were detected in 11 pulsars. These included 12 glitches in PSR J1341−6220, corresponding to a glitch rate of 1.5 glitches per year. We also detected the largest known glitch, in PSR J1614−5047, with ∆ν g /ν ≈ 6.5 × 10 −6 where ν = 1/P is the pulse frequency. Glitch parameters were determined both by extrapolating timing solutions to inter-glitch intervals and by phase-coherent timing fits across the glitch(es). These fits also gave improved positions and dispersion measures for many of the pulsars. Analysis of glitch parameters, both from this work and from previously published results, shows that most glitches have a fractional amplitude ∆ν g /ν of between 10 −8 and 10 −6 . There is no consistent relationship between glitch amplitude and the time since the previous glitch or the time to the following glitch, either for the ensemble or for individual pulsars. As previously recognised, the largest glitch activity is seen in pulsars with ages of order 10 4 years, but for about 30 per cent of such pulsars, no glitches were detected in the 8-year data span. There is some evidence for a new type of timing irregularity in which there is a significant increase in pulse frequency over a few days, accompanied by a decrease in the magnitude of the slowdown rate. Fits of an exponential recovery to post-glitch data show that for most older pulsars, only a small fraction of the glitch decays. In some younger pulsars, a large fraction of the glitch decays, but in others, there is very little decay. Apart from the Crab pulsar, there is no clear dependence of recovery timescale on pulsar age.

VLT observations of the twoFermipulsars PSR J1357−6429 and PSR J1048−5832

“…Thus, the apparent inconsistency between the Chandra and radio-timing positions cannot be explained by the pulsar proper motion, but by a genuine difference in the astrometry of either of the two observations. In this respect, we note that the radio-timing position of Wang et al (2000) is also inconsistent with the radio-interferometry one of Stappers et al (1999), which suggests that the former might be affected by systematics and has to be taken with caution. Indeed, such an inconsistency has also been noted by Wang et al (2000) who attributed it to the effect of timing noise following period irregularities after a glitch.…”

“…This implies that also the Chandra coordinates of PSR J1048−5832 are free from systematics. We also compared the Wang et al (2000) radio-timing position with that obtained by the Fermi Pulsar Timing Consortium and found no obvious difference. The time span between the epochs of the Chandra and the radio-timing observations of PSR J1048−5832 is ∼5.39 yrs, which would imply a proper motion of 0.…”

“…1 ± 1. 3) from the radio-timing one (Wang et al 2000), obtained from observations performed with the Australia Telescope National Facility (ATNF) Parkes radio telescope. On the other hand, the difference with respect to the radiointerferometry position obtained from observations performed with the ATCA (Stappers et al 1999) is not significant.…”

Deep optical imaging of theγ-ray pulsar J1048–5832 with the VLT

“…The X-ray image is corrected for the ACIS exposure map and smoothed with a four-pixel Gaussian kernel to highlight the PWN shape. The X-ray position of the pulsar and its 1σ uncertainty are marked together with the radio interferometric (Stappers et al 1999) 8 and timing (Wang et al 2000) 9 ones. The X-ray position agrees well with the interferometric one.…”

Detection of very-high-energyγ-ray emission from the vicinity of PSR B1706–44 and G 343.1–2.3 with H.E.S.S.

“…J1708−443. Wang et al 2000). In this observation mode, the array is pointed toward a position offset from the source of interest to allow simultaneous background estimation.…”