Cooling of neutron stars and hybrid stars with a stiff hadronic EoS

摘要

Within the "nuclear medium cooling" scenario of neutron stars all reliably known temperature-age data, including those of the central compact objects in the supernova remnants of Cassiopeia A and XMMU-J1732, can be comfortably explained by a set of cooling curves obtained by variation of the star mass within the range of typical observed masses. The recent measurements of the masses of the pulsars PSR J1616-2230, PSR J0348-0432 and J00737-3039B and the companion of J1756-2251 provide independent proof for the existence of neutron stars with masses in a broad range from 1.2 to 2M (aS (TM)) The values M > 2M (aS (TM)) call for sufficiently stiff equations of state for neutron star matter. We investigate the response of the set of neutron star cooling curves to a stiffening of the nuclear equation of state so that maximum masses of about 2.4M (aS (TM)) would be accessible and to a deconfinement phase transition from such stiff nuclear matter in the outer core to color superconducting quark matter in the inner core. Without a readjustment of cooling inputs the mass range required to cover all cooling data for the stiff DD2 equation of state should include masses of 2.426M (aS (TM)) for describing the fast cooling of CasA while the existence of a quark matter core accelerates the cooling so that CasA cooling data are described with a hybrid star of mass 1.674M (aS (TM)).