Late Emission from the Type Ib/c SN 2001em: Overtaking the Hydrogen Envelope
Abstract
The Type Ib/c supernova SN 2001em was observed to have strong radio, X-ray, and Hα emission at an age of ~2.5 yr. Although the radio and X-ray emission have been attributed to an off-axis gamma-ray burst, we model the emission as the interaction of normal SN Ib/c ejecta with a dense, massive (~3 Msolar) circumstellar shell at a distance of ~7×1016 cm. We investigate two models, in which the circumstellar shell has or has not been overtaken by the forward shock at the time of the X-ray observation. The circumstellar shell was presumably formed by vigorous mass loss with a rate of ~(2-10)×10-3 Msolar yr-1 at ~(1-2)×103 yr prior to the supernova explosion. The hydrogen envelope was completely lost and subsequently was swept up and accelerated by the fast wind of the presupernova star up to a velocity of 30-50 km s-1. Although interaction with the shell can explain most of the late emission properties of SN 2001em, we need to invoke clumping of the gas to explain the low absorption at X-ray and radio wavelengths.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2006
- DOI:
- 10.1086/500539
- arXiv:
- arXiv:astro-ph/0510362
- Bibcode:
- 2006ApJ...641.1051C
- Keywords:
-
- Stars: Mass Loss;
- Stars: Supernovae: General;
- Stars: Supernovae: Individual: Alphanumeric: SN 2001em;
- Astrophysics
- E-Print:
- 26 pages, 4 figures, ApJ submitted