Astrophysical Signals of Quark Matter

Abstract : Because of the tremendous pressures in the cores of neutron stars, the nuclear boundaries of neutrons, protons plus other constitutes in the centers of neutron stars may dissolve into their constituent quarks, creating the novel state of ultradense matter known as quark matter. In my talk, I will emonstrated that the existence of such matter in neutron stars could lead to a dramatic, observable anomaly in the timing structure of isolated pulsars. This analysis is extended to the spin evolution of neutron stars in binary systems (X-ray pulsars), which are being spun up by mass transfer from accretion disks. It is found that quark deconfinement in such pulsars, induced by the changing spin period, can lead to a dramatic saturation in the pulsar's spin frequency. This finding provides a possible explanation for the observed, anomalous spin frequency distribution of neutron stars in low-mass X-ray binaries.