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Taking the "Un" out of "Unnovae"

Piro, Anthony L. (2013) Taking the "Un" out of "Unnovae". Astrophysical Journal Letters, 768 (1). Art. No. L14. ISSN 2041-8205.

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It has long been expected that some massive stars produce stellar mass black holes (BHs) upon death. Unfortunately, the observational signature of such events has been unclear. It has even been suggested that the result may be an "unnova," in which the formation of a BH is marked by the disappearance of a star rather than an electromagnetic outburst. I argue that when the progenitor is a red supergiant, evidence for BH creation may instead be a ≈3-10 day optical transient with a peak luminosity of ≈10^(40)-10^(41) erg s^(–1), a temperature of ≈10^4 K, slow ejection speeds of ≈200 km s^(–1), and a spectrum devoid of the nucleosynthetic products associated with explosive burning. This signal is the breakout of a shock generated by the hydrodynamic response of a massive stellar envelope when the protoneutron star loses ~few × 0.1 M☉ to neutrino emission prior to collapse to a BH. Current and future wide-field, high-cadence optical surveys make this an ideal time to discover and study these events. Motivated by the unique parameter space probed by this scenario, I discuss more broadly the range of properties expected for shock breakout flashes, with an emphasis on progenitors with large radii and/or small shock energies. This may have application in a wider diversity of explosive events, from pair instability supernovae to newly discovered but yet to be understood transients.

Item Type:Article
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URLURL TypeDescription Paper
Piro, Anthony L.0000-0001-6806-0673
Additional Information:© 2013 The American Astronomical Society. Received 2013 March 19; accepted 2013 April 3; published 2013 April 17. I thank Elizabeth Lovegrove and Stan Woosley for sharing their models and helpful discussions of their work. I also thank Christopher Kochanek, Evan O’Connor, and Christian Ott for feedback on previous drafts. This work was supported through NSF grants AST-1212170, PHY-1151197, and PHY-1068881, NASA ATP grant NNX11AC37G, and by the Sherman Fairchild Foundation.
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Sherman Fairchild FoundationUNSPECIFIED
Subject Keywords:black hole physics; shock waves; stars: evolution; supernovae: general
Issue or Number:1
Record Number:CaltechAUTHORS:20130415-091257984
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Official Citation:Taking the "Un" out of "Unnovae" Anthony L. Piro 2013 ApJ 768 L14
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37930
Deposited By: Ruth Sustaita
Deposited On:15 Apr 2013 16:27
Last Modified:03 Oct 2019 04:52

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