Chandra Observations of SN 2004et and the X-ray Emission of Type IIp Supernovae

Abstract

We report the X-ray detection of the Type II-plateau supernova SN 2004et in the spiral galaxy NGC 6946, using the Chandra X-Ray Observatory. The position of the X-ray source was found to agree with the optical position within ~0.4 arcsec. Chandra also surveyed the region before the 2004 event, finding no X-ray emission at the location of the progenitor. For the post-explosion observations, a total of 202, 151, and 158 photons were detected in three pointings, each ~29 ks in length, on 2004 October 22, November 6, and December 3, respectively. The spectrum of the first observation is best fit by a thermal model with a temperature of kT=1.3 keV and a line-of-sight absorption of N_H=1.0 x 10^{22} cm^{-2}. The inferred unabsorbed luminosity (0.4-8 keV) is ~4x10^{38} erg/s, adopting a distance of 5.5 Mpc. A comparison between hard and soft counts on the first and third epochs indicates a softening over this time, although there is an insufficient number of photons to constrain the variation of temperature and absorption by spectral fitting. We model the emission as arising from the reverse shock region in the interaction between the supernova ejecta and the progenitor wind. For a Type IIP supernova with an extended progenitor, the cool shell formed at the time of shock wave breakout from the star can affect the initial evolution of the interaction shell and the absorption of radiation from the reverse shock. The observed spectral softening might be due to decreasing shell absorption. We find a pre-supernova mass loss rate of (2-2.5)x 10^{-6} M_{\odot} /yr for a wind velocity of 10 kms, which is in line with expectations for a Type IIP supernova.

arXiv commenttotal 19 pages including 7 figures. ApJ, in press. See http://spider.ipac.caltech.edu/staff/rho/preprint/SN2004etms.ps for the paper including full resolution images

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Cited by in corpus (9)

• The progenitor mass of the Type IIP supernova SN 2004et from late-time spectral modeling
• Dust and the type II-plateau supernova 2004et
• Optical and near infrared coverage of SN 2004et: physical parameters and comparison with other type IIP supernovae
• What are Published X-ray lightcurves telling us about Young Supernova Expansion?
• High mass of the type IIP supernova 2004et inferred from hydrodynamic modeling
• The Long-Term Variability of the X-Ray Sources in NGC 6946 and NGC 4485/4490
• The progenitor of SN 2011ja: Clues from circumstellar interaction
• X-Ray emission from SN 2004dj: A Tale of Two Shocks
• Circumstellar Na I and Ca II lines in type IIP supernovae and SN 1998S