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Probing Shock Breakout with Serendipitous GALEX Detections of Two SNLS Type II-P Supernovae

Gezari, Suvi and Dessart, Luc and Basa, Stéphane and Martin, D. Christopher and Neill, James D. and Woosley, S. E. and Hillier, D. John and Bazin, Gurvan and Forster, Karl and Friedman, Peter G. and Le Du, Jérémy and Mazure, Alain and Morrissey, Patrick and Neff, Susan G. and Schiminovich, David and Wyder, Ted K. (2008) Probing Shock Breakout with Serendipitous GALEX Detections of Two SNLS Type II-P Supernovae. Astrophysical Journal Letters, 683 (1). L131-L134. ISSN 2041-8205. doi:10.1086/591647.

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We report the serendipitous detection by GALEX of fast (<1 day) rising (≳1 mag) UV emission from two Type II plateau (II-P) supernovae (SNe) at z = 0.185 and 0.324 discovered by the Supernova Legacy Survey. Optical photometry and VLT spectroscopy 2 weeks after the GALEX detections link the onset of UV emission to the time of shock breakout. Using radiation hydrodynamics and non-LTE radiative transfer simulations, and starting from a standard red supergiant (RSG; Type II-P SN progenitor) star evolved self-consistently from the main sequence to iron core collapse, we model the shock breakout phase and the 55 hr that follow. The small scale height of our RSG atmosphere model suggests that the breakout signature is a thermal soft X-ray burst (λpeak ~ 90 Å) with a peak duration of ≾2000 s. Longer durations are possible but require either an extended and tenuous nonstandard envelope or an unusually dense RSG wind with M ~ 10^(-3)M_☉yr^(-1). The GALEX observations miss the peak of the luminous (M_(FUV)≈ − 20), UV burst but unambiguously capture the rise of the emission and a subsequent 2 day long plateau. The postbreakout, UV-bright plateau is a prediction of our model in which the shift of the peak of the spectral energy distribution (SED) from ∼100 to ∼1000 Å and the ejecta expansion both counteract the decrease in bolometric luminosity from ∼10^(11) to ~ 10^9 L_☉ over that period. Based on the observed detection efficiency of our study, we make predictions for the breakout detection rate of the GALEX Time Domain Survey.

Item Type:Article
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URLURL TypeDescription
Gezari, Suvi0000-0003-3703-5154
Martin, D. Christopher0000-0002-8650-1644
Neill, James D.0000-0002-0466-1119
Forster, Karl0000-0001-5800-5531
Morrissey, Patrick0000-0001-8177-1023
Additional Information:© 2008 The American Astronomical Society. Print publication: Issue 2 (2008 August 20) Received 2008 April 7, accepted for publication 2008 July 8 Published 2008 July 31. We thank the anonymous referee for their helpful comments. L. D. acknowledges support for this work from the SciDAC program of the DOE, under grants DE-FC02-01ER41184 and DE-FC02-06ER41452, and from the NSF under grant AST- 0504947. S. W. acknowledges support from the SciDAC under grant DE-FC02-06ER41438 and also by NASA under grant NNG05GG28G. S. G. and S. B. thank Bruno Milliard for his support during this study. We gratefully acknowledge NASA’s support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with CNES of France and the Korean MOST. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the CFHT, which is operated by the NRC of Canada, the INSU of the CNRS of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the CADC as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS. Based on observations made with the ESO telescopes at the La Silla or Paranal Observatories under proposal IDs 171.A-0486 and 176.A-0589.
Group:Space Radiation Laboratory, Space Astrophysics Laboratory
Funding AgencyGrant Number
Department of Energy (DOE)DE-FC02-01ER41184
Department of Energy (DOE)DE-FC02-06ER41452
Department of Energy (DOE)DE-FC02-06ER41438
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Ministry of Science and Technology (Korea)UNSPECIFIED
European Southern Observatory - La Silla or Paranal Observatories171.A-0486
European Southern Observatory - La Silla or Paranal Observatories176.A-0589
Subject Keywords:radiative transfer; stars: atmospheres; supernovae: general; ultraviolet: ISM
Issue or Number:1
Record Number:CaltechAUTHORS:20091013-202239042
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Official Citation:Probing Shock Breakout with Serendipitous GALEX Detections of Two SNLS Type II-P Supernovae Suvi Gezari, Luc Dessart, Stéphane Basa, D. Chris Martin, James D. Neill, S. E. Woosley, D. John Hillier, Gurvan Bazin, Karl Forster, Peter G. Friedman, Jérémy Le Du, Alain Mazure, Patrick Morrissey, Susan G. Neff, David Schiminovich, and Ted K. Wyder 2008 ApJ 683 L131-L134 doi: 10.1086/591647
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16337
Deposited By: Joy Painter
Deposited On:14 Oct 2009 16:18
Last Modified:08 Nov 2021 23:26

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