Strange Pulsar Hypothesis

It appears that there is a genuine shortage of radio pulsars with surface magnetic fields significantly smaller than $\sim 10^8$ Gauss. We propose that the pulsars with very low magnetic fields are actually strange stars locked in a state of minimum free energy and therefore at a limiting value of the magnetic field which can not be lowered by the system spontaneously.Comment: 4 pages, 1 figure, uses LaTeX2e(mn2e.cls) and astrobib(mnras.bst), accepted in MNRA

The micro-glitch in PSR B1821-24 : A case for a strange pulsar?

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 ($\Delta \nu / \nu \sim 10^{-11}$) 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 $2.25\times10^9 G$. We have suggested earlier that some of the recycled pulsars could actually be strange quark stars. In this work we argue that the crustal properties of such a {\em strange} pulsar are just right to give rise to a glitch of this magnitude, explaining the scarcity of larger glitches in millisecond pulsars.Comment: 5 pages, 5 figures, uses LaTeX2e(mn2e.cls) and astrobib(mn2e.bst): text substantially modified, to be published in MNRA