Pulsar Glitches In Young Pulsars

Pulsar glitch,which is characterized by an abrupt increase in spin frequency?v?,is a rare and bizarre phenomenon of irregularity in rotation.To date,a total of 555 glitches in190 pulsars have been reported.Since the first glitch was detected to occur in the Vela pulsar in 1969,although more and more events have been observed,there is no obvious law.Moreover,the three theoretical models used to explain the mechanism behind of glitch have their own limitations,and have not made much progress in recent decades years.The present thesis is an attempt to search more pulsar glitches using timing observations at Parkes.In our work,data spans for each pulsar ranged between 3 yr and 7 yr?32 glitch events have been detected in 20 radio pulsars after carrying out timing residuals analysis.Out of these glitches,28 are new discoveries,and 4 have previously been reported with new exponential relaxation updated in each glitch.These glitches,ranging from0.75×10^-9 to 8.6×10^-6 at the change in relative glitch sizes?v/v,appear like bimodal distribution.In special,the first spin-up events are discovered in 8 pulsars.Most glitches behave in normal behaviours,and an unusual slow glitch is observed in PSR J1602-5100.This is the largest slow glitch detected so far,with the fractional size of?v_max/v?152×10^-9.All large glitches follow a few thousandths change in???,and lower?one order of magnitude?change appears in small glitches.For the post-glitch recoveries,most glitches exhibit a long-term linear recovery and only 8 exponential relaxations are discovered in this work.These exponential decays occurred in large glitches with low,by just a few percent.Observed time constant ?_d for exponential recoveries range from 29 d and 100 d.Additionally,it is obvious that the relatively older glitching pulsars prefer undergoing small glitches,and large glitches all occur in the comparatively younger pulsars.Meanwhile,we found that this slow glitch is linked to changes in the shape of the pulse profile.A new profile component appeared during the slow glitch and disappeared at the end of this event,which is different from the two mode changes following normal glitches.This suggests that slow glitch has a possible different origin from that of normal glitch and should be classified as a new type of pulsar spin irregularity.