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Radioactively Powered Rising Light Curves of Type Ia Supernovae

Piro, Anthony L. (2012) Radioactively Powered Rising Light Curves of Type Ia Supernovae. Astrophysical Journal, 759 (2). Art. No. 83. ISSN 0004-637X.

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The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first ≈0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X_(56) ≈ (4-6) × 10^(–2) of ^(56)Ni distributed between a depth of ≈10^(–2) and 0.3 M_☉ below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

Item Type:Article
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Piro, Anthony L.0000-0001-6806-0673
Additional Information:© 2012 American Astronomical Society. Received 2012 January 25; accepted 2012 September 23; published 2012 October 19. I thank the referee for detailed comments and suggestions. I also thank Lars Bildsten, Luc Dessart, Dan Kasen, Peter Goldreich, Christian Ott, Ken Shen, and Stan Woosley for helpful comments and discussions. This work was supported through NSF grant AST-0855535 and by the Sherman Fairchild Foundation.
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Sherman Fairchild FoundationUNSPECIFIED
Subject Keywords:hydrodynamics; shock waves; supernovae: general; white dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:20121218-084029342
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Official Citation:Radioactively Powered Rising Light Curves of Type Ia Supernovae Anthony L. Piro doi:10.1088/0004-637X/759/2/83
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36023
Deposited By: Ruth Sustaita
Deposited On:18 Dec 2012 16:58
Last Modified:03 Oct 2019 04:34

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