2003/06/05 by J. M. Laming, J. Martin Laming, Una Hwang · 9 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Asymmetry #Cassiopeia A #Ejecta #Envelope (radar) #Gamma-ray bursts and supernovae #Ion #Ionization #Jet (fluid) #Mechanics #Physics #Spectral line #Supernova #Supernova remnant #astro-ph
paper · pdf · doi:10.1086/378268
published as Astrophys.J. 597 (2003) 347-361 · 32 pages, submitted to ApJ
arxiv created 2003/06/05 · openalex publication_date 2003/10/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a detailed analysis of Chandra X-ray spectra from individual ejecta knots in the supernova remnant Cassiopeia A. The spectra are fitted to give the electron temperature T(sub e), and (single) ionization age n(sub e)t. These quantities are compared with the predictions of self similar hydrodynamic models incorporating time dependent ionization and radiation losses, and Coulomb electron-ion equilibration behind the reverse shock, for a variety of different ejecta density profiles described by a uniform density core and a power law envelope. We find that the ejecta close to the 'jet' region in the NE, but not actually in the jet itself, have a systematically shallower outer envelope than ejecta elsewhere in the remnant, and we interpret this as being due to more energy of the initial explosion being directed in this polar direction as opposed to equatorially. The degree of asymmetry we infer is at the low end of that generally modelled in asymmetric core-collapse simulations, and may be used to rule out highly asymmetric explosion models.