The neutrino signal from protoneutron star accretion and black hole formation

Context: We discuss the formation of stellar mass black holes via protoneutron star (PNS) collapse. In the absence of an earlier explosion, the PNS collapses to a black hole due to the continued mass accretion onto the PNS. We present an analysis of the emitted neutrino spectra of all three flavors during the PNS contraction.
Aims: Special attention is given to the physical conditions which depend on the input physics, e.g. the equation of state (EoS) and the progenitor model.
Methods: The PNSs are modeled as the central object in core collapse simulations using general relativistic three-flavor Boltzmann neutrino transport in spherical symmetry. The simulations are launched from several massive progenitors of 40 M(_⊙) and 50 M(_⊙).
Results: We analyze the electron-neutrino luminosity dependencies and construct a simple approximation for the electron-neutrino luminosity, which depends only on the physical conditions at the electron-neutrinosphere. In addition, we analyze different μ,τ-neutrino pair-reactions separately and compare the differences during the post-bounce phases of failed core collapse supernova explosions of massive progenitors. We also investigate the connection between the increasing μ,τ-neutrino luminosity and the PNS contraction during the accretion phase before black hole formation.
Conclusions: Comparing the different post bounce phases of the progenitor models under investigation, we find large differences in the emitted neutrino spectra. These differences and the analysis of the electron-neutrino luminosity indicate a strong progenitor model dependency of the emitted neutrino signal.