Effects of trapped neutrinos on the composition and structure of massive protoneutron stars

摘要

The properties of massive protoneutron stars (PNSs) are of great significance for the study of supernova and the evolution of neutron stars or black holes. The mass of the massive neutron star PSR J1614-2230 is fitted by selecting the nuclear coupling constants and adjusting the hyperon coupling constants in the framework of the relativistic mean field (RMF) theory. The model is then extrapolated to calculate the properties of massive PNS with the trapped neutrinos. The effects of different trapped neutrinos on the composition and structure of massive PNSs are discussed for entropy per baryon S = 1. Results show that the presence of trapped neutrinos increase the energy density. Moreover, the significant neutrinos trapped, such as electron leptons number Y-L = 0.4, reduces the pressure of massive PNSs in the density region 0.2-0.5 fm(-3), that is to say, the equation-of-state (EOS) is softened in this region. The maximum masses and corresponding radii of massive PNSs are calculated to be 2.110 M-circle dot, 2.106 M-circle dot, 2.095 M-circle dot, 2.082 M-circle dot and 12.19, 11.88, 11.75 and 11.81 km for the electron leptons number Y-L = 0.1, 0.2, 0.3, 0.4. We calculate the distribution of the internal temperature, and get the effects of the trapped neutrinos on the internal temperature of massive PNSs for the first time. For the different electron leptons number YL = 0.1, 0.2, 0.3, 0.4, the central temperatures of the massive PNS, when the mass is taken to be the same as that of the observed neutron star PSR J1614-2230(1.97 +/- 0.04 M-circle dot), are 19.57(-0.19)(+0.32), 22.55(-0.25)(+0.36), 25.48(-0.45)(+0.68), 27.47(-0.83)(+0.93) MeV, respectively.