Detection of 107 glitches in 36 southern pulsars

Abstract

Timing observations from the Parkes 64-m radio telescope for 165 pulsars between 1990 and 2011 have been searched for period glitches. Data spans for each pulsar ranged between 5.3 years and 20.8 years. From the total of 1911 years of pulsar rotational history, 107 glitches were identified in 36 pulsars. Out of these glitches, 61 have previously been reported whereas 46 are new discoveries. Glitch parameters, both for the previously known and the new glitch detections, were measured by fitting the timing residual data. Observed relative glitch sizes ∆ν g /ν range between 10 −10 and 10 −5 , where ν = 1/P is the pulse frequency. We confirm that the distribution of ∆ν g /ν is bimodal with peaks at approximately 10 −9 and 10 −6 . Glitches are mostly observed in pulsars with characteristic ages between 10 3 and 10 5 years, with large glitches mostly occurring in the younger pulsars. Exponential post-glitch recoveries were observed for 27 large glitches in 18 pulsars. The fraction Q of the glitch that recovers exponentially also has a bimodal distribution. Large glitches generally have low Q, typically just a few per cent, but large Q values are observed in both large and small glitches. Observed time constants for exponential recoveries ranged between 10 and 300 days with some tendency for longer timescales in older pulsars. Shorter timescale recoveries may exist but were not revealed by our data which typically have observation intervals of 2 -4 weeks. For most of the 36 pulsars with observed glitches, there is a persistent linear increase inν (i.e., decrease in the slow-down rate |ν|) in the inter-glitch interval. Where an exponential recovery is also observed, the effects of this are superimposed on the linear increase inν. In some but not all cases, the slope of the linear recovery changes at the time of a glitch. Theν values characterising the linear changes inν are almost always positive and, after subtracting the magnetospheric component of the braking, are approximately proportional to the ratio of |ν| and the inter-glitch interval, as predicted by vortex-creep models.

The Einstein@home Gamma-Ray Pulsar Survey. I. Search Methods, Sensitivity, and Discovery of New Young Gamma-Ray Pulsars

“…If the photon data are sparse, as is often the case, this can happen before we have even detected any pulsed photons after the glitch (Yu et al 2013;Clark et al 2015). A result is that the likelihood distribution in the glitch epoch, t g , resembles a comb of possible epochs, with each maximum occurring at a time where ∆Φ g (t) equals an integer number of rotations.…”

“…Yu et al 2013). Pulsars with large glitches are particularly difficult to detect in blind searches, which require long intervals containing a stable signal to accumulate sufficient S/N.…”

Post-glitch exponential relaxation of radio pulsars and magnetars in terms of vortex creep across flux tubes

“…While most canonical radio pulsar glitches (for exceptions see Archibald et al (2016) and references in Akbal et al (2015)) are not followed by changes correlated with external torque variation (Espinoza et al 2011;Yu et al 2013), magnetar glitches are accompanied by radiative changes and bursting activity (Dib & Kaspi 2014). This fact indicates that glitches reflect angular momentum exchange between the observed crust and interior components of the neutron star.…”

“…glitches, occasionally. Glitch events manifest in timing data as fractional changes in the rotation rate with ∆Ω/Ω ∼ 10 −11 − 10 −5 and are usually accompanied by jumps in the spin-down rate, ∆Ω/Ω ∼ 10 −4 − 10 −1 (Espinoza et al 2011;Yu et al 2013;Shabanova et al 2013;Dib & Kaspi 2014). Both of these changes tend to relax back to the original preglitch state fully or partially on timescales of the order of several days to a few years.…”

Understanding the spin-down rate changes of PSR B0919+06

“…a sudden increase in rotational frequency; e.g. Espinoza et al 2011;Yu et al 2013) and lowfrequency timing noise. These spin irregularities are generally seen in pulsar timing residuals; i.e.…”