Hyperon Matter and Black Hole Formation in Failed Supernovae

We investigate the emergence of hyperons in black-hole-forming failed supernovae, which are caused by the dynamical collapse of nonrotating massive stars. We perform neutrino-radiation hydrodynamical simulations in general relativity adopting realistic hyperonic equation-of-state (EOS). Attractive and repulsive cases are examined for the potential of \Sigma\ hyperons. Since hyperons soften the EOS, they shorten the time interval from the bounce to black hole formation, which corresponds to the duration of neutrino emission. This effect is larger for the attractive case than the repulsive case because \Sigma\ hyperons appear more easily. In addition, we investigate the impacts of pions to find that they also promotes the recollapse towards the black hole formation.