Signal of Quark Deconfinement in Millisecond Pulsars and Reconfinement in Accreting X-ray Neutron Stars

Abstract

Theoretically, the phase transition between the confined and deconfined phases of quarks can have a remarkable effect on the spin properties of millisecond pulsars and on the spin distribution of the population of x-ray neutron stars in lowmass binaries. In the latter class of stars, the effect has already been observed-a strong clustering in the population in a narrow band of spins. The observed clustering cannot presently be uniquely assigned to the phase transition as cause. However, there is another possible signal-not so far observed-in millisecond pulsars that we also discuss which would have the same origin, and whose discovery would tend to confirm the interpretation in terms of a phase transition in the stellar core.