Soderberg 2006 SN 2003bg 射电和X射线

主要内容:
此暴既又详细的射电数据，也有X射线的观测。一般超新星并没有观测的到的X射线的数据的。

精彩摘抄:

射电光变

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Title:		The Radio and X-Ray Luminous SN 2003bg and the Circumstellar Density Variations around Radio Supernovae
Authors:		Soderberg, A. M.; Chevalier, R. A.; Kulkarni, S. R.; Frail, D. A.
Affiliation:		AA(Division of Physics, Mathematics and Astronomy, 105-24, California Institute of Technology, Pasadena, CA 91125.), AB(Department of Astronomy, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903-0818.), AC(Division of Physics, Mathematics and Astronomy, 105-24, California Institute of Technology, Pasadena, CA 91125.), AD(National Radio Astronomy Observatory, Socorro, NM 87801.)
Publication:		The Astrophysical Journal, Volume 651, Issue 2, pp. 1005-1018. (ApJ Homepage)
Publication Date:		11/2006
Origin:		UCP
ApJ Keywords:		Radiation Mechanisms: Nonthermal, Radio Continuum: General, supernovae: individual (SN 2003bg)
Abstract Copyright:		(c) 2006: The American Astronomical Society
DOI:		10.1086/507571
Bibliographic Code:		2006ApJ...651.1005S

Abstract

We report extensive radio and X-ray observations of SN 2003bg, whose spectroscopic evolution shows a transition from a broad-lined Type Ic to a hydrogen-rich Type II, and later to a typical hydrogen-poor Type Ibc. We show that the extraordinarily luminous radio emission is well described by a self-absorption-dominated synchrotron spectrum, while the observed X-ray emission at t~30 days is adequately fit by inverse Compton scattering of the optical photons off of the synchrotron-emitting electrons. Our radio model implies a subrelativistic ejecta velocity, v~0.24c, at t₀~10 days after the explosion, which emphasizes that broad optical absorption lines do not imply relativistic ejecta. We find that the total energy of the radio-emitting region evolves as E~7.3×10⁴⁸(t/t₀)^0.4 ergs, assuming equipartition of energy between relativistic electrons and magnetic fields (ɛ_e=ɛ_B=0.1). The circumstellar density is well described by a stellar wind profile, with modest (factor of ~2) episodic density enhancements that produce abrupt achromatic flux variations. We estimate an average mass-loss rate of M˙~3×10^-4 M_solar yr^-1 (assuming a wind velocity of v_w=10³ km s^-1) for the progenitor, consistent with the observed values for Galactic Wolf-Rayet stars. Comparison with other events reveals that ~50% of radio supernovae show similar short-timescale flux variations, attributable to circumstellar density irregularities. Specifically, the radio light curves of SN 2003bg are strikingly similar to those of the Type IIb SN 2001ig, suggestive of a common progenitor evolution for these two events. Based on the relative intensity of the inferred density enhancements, we conclude that the progenitors of SNe 2003bg and 2001ig experienced quasi-periodic mass-loss episodes just prior to the SN explosion. Finally, this study emphasizes that abrupt radio light-curve variations cannot be used as a reliable proxy for an engine-driven explosion, including off-axis gamma-ray bursts.

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