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

Abstract

Theoretically, the phase transition between the confinedand deconfined phases of quarks can have a remarkable effect on thespin properties of millisecond pulsars and on the spin distributionof the population of x-ray neutron stars in low-mass binaries. Inthe latter class of stars, the effect has already been observed--astrong clustering in the population in a narrow band of spins. Theobserved clustering cannot presently be uniquely assigned to the phasetransition as cause. However, there is another possible signal--not so farobserved--in millisecond pulsars that we also discuss which wouldhave the same origin, and whose discovery would tend to confirm theinterpretation in terms of a phase transition in the stellar core.