Black Hole Formation in Failing Core-Collapse Supernovae
We present results of a systematic study of failing core-collapse supernovae and the formation of stellar-mass black holes (BHs). Using our open-source general-relativistic 1.5D code GR1D equipped with a three-species neutrino leakage/heating scheme and over 100 presupernova models, we study the effects of the choice of nuclear equation of state (EOS), zero-age main sequence (ZAMS) mass and metallicity, rotation, and mass-loss prescription on BH formation. We find that the outcome, for a given EOS, can be estimated, to first order, by a single parameter, the compactness of the stellar core at bounce. By comparing protoneutron star (PNS) structure at the onset of gravitational instability with solutions of the Tolman–Oppenheimer–Volkof equations, we find that thermal pressure support in the outer PNS core is responsible for raising the maximum PNS mass by up to 25% above the cold NS value. By artificially increasing neutrino heating, we find the critical neutrino heating efficiency required for exploding a given progenitor structure and connect these findings with ZAMS conditions, establishing, albeit approximately, for the first time based on actual collapse simulations, the mapping between ZAMS parameters and the outcome of core collapse. We also study the effect of progenitor rotation and find that the dimensionless spin of nascent BHs may be robustly limited below a* = Jc/GM^2 = 1 by the appearance of nonaxisymmetric rotational instabilities.
Additional Information© 2011 American Astronomical Society. Received 2010 October 26; accepted 2011 January 10; published 2011 March 7. We acknowledge helpful discussions with and input from A. Burrows, P. Cerdá-Durán, L. Dessart, M. Duez, T. Fischer, J. Kaplan, J. Lattimer, C. Meakin, J. Murphy, F. Peng, S. Phinney, C. Reisswig, S. Scheidegger, N. Smith, E. Schnetter, K. Thorne, and S. Teukolsky. We thank S. Woosley and A. Heger for their recent presupernova models and A. Chieffi and M. Limongi for making available both of their presupernova model sets. The computations were performed at Caltech's Center for Advanced Computing Research on the cluster "Zwicky" funded through NSF grant no. PHY-0960291 and the Sherman Fairchild Foundation. Furthermore, computations were performed on Louisiana Optical Network Infrastructure computer systems under allocation loni_numrel05, on the NSF Teragrid under allocation TG-PHY100033, and on resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231. This research is supported in part by the National Science Foundation under grant nos. AST-0855535 and OCI-0905046. EOC is supported in part by a post-graduate fellowship from the Natural Sciences and Engineering Research Council of Canada (NSERC).
Published - OConnor2011p13391Astrophys_J.pdf