A study of 315 glitches in the rotation of 102 pulsars

Abstract

The rotation of more than 700 pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 pulsars. Combining these new data with those already published, we present a data base containing 315 glitches in 102 pulsars. The data base was used to study the glitch activity among the pulsar population, finding that it peaks for pulsars with a characteristic age c 10 kyr and decreases for longer values of c , disappearing for objects with c > 20 Myr. The glitch activity is also smaller in the very young pulsars ( c 1 kyr). The cumulative effect of glitches, a collection of instantaneous spin-up events, acts to reduce the regular long-term spin-down rate || of the star. The percentage of || reversed by glitch activity was found to vary between 0.5 and 1.6 per cent for pulsars with spin-down rates || between 10 -14 and 3.2 10 -11 Hz s -1 , decreasing to less than 0.01 per cent at both higher and lower spin-down rates. These ratios are interpreted in terms of the amount of superfluid involved in the generation of glitches. In this context, the activity of the youngest pulsar studied, the Crab pulsar, may be explained by quake-like activity within the crust. Pulsars with low spin-down rates seem to exhibit mostly small glitches, matching well the decrease of their crustal superfluid.