Spin change of a proto-neutron star by the emission of neutrinos

We investigate the structure of proto-neutron stars (PNSs) with trapped neutrinos by using a quark-meson coupling model. We adopt a phenomenological lepton density which is diffuse near the surface. We calculate the populations of baryons and leptons, the equations of state, and the mass-radius relation for isentropic PNS models. In addition, the moment of inertia is calculated for both PNS and cold-neutron-star (CNS) models as a means to study the change of the spin period due to the neutrino emission from a PNS. Neutrino emission from a hyperonic neutron star is shown to increase the spin by about 10% of the initial spin, while the spin of a nucleonic neutron star with a central density above ρ_C≈5ρ₀ is decreased by a few % by the emission of neutrinos. Therefore, the spin change owing to the leakage of neutrinos from a PNS is a small (<10%) correction compared to other processes related to the spin change.