Homologous Core Collapse in a Massive Star and Self-Similar Evolution of Rebound Shocks

摘要

During the gravitational core collapse of a massive progenitor star which may give rise to at least a class ofgamma-ray bursts(GRBs)associated with supernovae,a stellar core rapidly passes through a short yet important phase ofneutronization,producing a huge amount of energetic neutrinos and photons which contribute to the total pressure withinthe progenitor core．The collection of neutrinos,photons and gas materials together may be approximated as a fluid with apolytropic index γ=4/3 under the action of self-gravity．With a substantial generalization and using analytical and numericalmethods (Lon & Cao 2008),we recently constructed and examined various self-similar solutions to describe collapses,rebound shocks and flows systematically in a γ=4/3 polytropic gas mixture with spherical symmetry,and compare our resultswith those of Goldreich & Weber (1980)．It is also possible to construct central void solutions without or with shocks．Variousfeatures and characteristics of this nonlinear relativistically hot gas dynamics,including asymptotic and exact solutions,arepresented．This more general polytropic model analysis provides the dynamic basis of understanding the evolution of reboundshocks in supernovae(SNs) and the results may be also utilized to benchmark hydrodynamic simulations．