Title: The micro-glitch in PSR B1821-24 : A case for the strange pulsar? Authors: Raka Dona Ray Mandal, Sushan Konar, Mira Dey, Jishnu Dey
The single glitch observed in PSR B1821-24, a millisecond pulsar in M28, is unusual on two counts. First, the magnitude of this glitch is at least an order of magnitude smaller (\Delta \nu / \nu ~ 10^{-11}) than the smallest glitch observed to date. Secondly, all other glitching pulsars have strong magnetic fields with B \gsim 10^{11} G and are young, whereas PSR B1821-24 is an old recycled pulsar with a field strength of 2.25 x 10^9 G. We have suggested earlier that some of the recycled pulsars could actually be strange quark stars (Ray Mandal et al., 2006). In this work we argue that the crustal properties of such a strange pulsar are just right to give rise to a glitch of this magnitude, explaining the scarcity of larger glitches in millisecond pulsars.