The neutrino signal from protoneutron star accretion and black hole formation

¹ Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland

² Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-1200, USA

Received: 29 September 2008
Accepted: 18 March 2009

Abstract

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 M and  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 -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 -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.