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Broadband Radiation from Primary Electrons in Very Energetic Supernovae

Ando, Shin'ichiro and Mészáros, Peter (2008) Broadband Radiation from Primary Electrons in Very Energetic Supernovae. Astrophysical Journal Letters, 689 (1). pp. 351-357. ISSN 2041-8205. doi:10.1086/592497.

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A class of very energetic supernovae (hypernovae) is associated with long gamma-ray bursts, in particular with a less energetic but more frequent population of gamma-ray bursts. Hypernovae also appear to be associated with mildly relativistic jets or outflows, even in the absence of gamma-ray bursts. Here we consider radiation from charged particles accelerated in such mildly relativistic outflows with kinetic energies of ~10^(50) ergs. The radiation processes of the primarily accelerated electrons considered are synchrotron radiation and inverse Compton scattering of synchrotron photons (synchrotron self-Compton; SSC) and of supernova photons (external inverse Compton; EIC). In the soft X-ray regime, both the SSC and EIC flux can be the dominant component, but due to their very different spectral shapes, it should be easy to distinguish between them. When the fraction of the kinetic energy going into the electrons (εe) is large, the SSC is expected to be important; otherwise, the EIC will dominate. The EIC flux is quite high, almost independently of εe, providing a good target for X-ray telescopes such as XMM-Newton and Chandra. In the GeV gamma-ray regime, the EIC would be the dominant radiation process and the Gamma-Ray Large Area Space Telescope (GLAST, which has been renamed the Fermi Gamma-ray Space Telesope) should be able to probe the value of εe, the spectrum of the electrons, and their maximum acceleration energy. Accelerated protons also lead to photon radiation through the secondary electrons produced by the photopion and photopair processes. We find that over a significant range of parameters the proton component is generally less prominent than the primary electron component. We discuss the prospects for the detection of the X-ray and GeV signatures of the mildly relativistic outflow of hypernovae.

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Additional Information:© 2008. The American Astronomical Society. Received 2008 June 16, accepted for publication 2008 August 11. We thank Katsuaki Asano for valuable comments. This work was supported by the Sherman Fairchild Foundation (S. A.) and by the NSF AST 03-07376 and NASA NAG 05-13286 (P. M.).
Funding AgencyGrant Number
Sherman Fairchild Foundation (S. A.)UNSPECIFIED
NSFAST 03-07376
NASANAG 05-13286 (P. M.)
Subject Keywords:gamma rays; bursts,radiation mechanisms; nonthermal, supernovae; general
Issue or Number:1
Record Number:CaltechAUTHORS:20090630-131941850
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Official Citation:Broadband Radiation from Primary Electrons in Very Energetic Supernovae Shin'ichiro Ando and Peter Mészáros 2008 ApJ 689 351-357 doi: 10.1086/592497
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14465
Deposited By: Ruth Sustaita
Deposited On:29 Aug 2009 00:55
Last Modified:08 Nov 2021 23:12

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