The Kinematics of Kepler's Supernova Remnant as Revealed by Chandra
Abstract
I have determined the expansion of the supernova remnant of SN 1604 (Kepler's supernova) based on archival Chandra ACIS-S observations made in 2000 and 2006. The measurements were done in several distinct energy bands, and were made for the remnant as a whole, and for six individual sectors. The average expansion parameter indicates that the remnant expands on average as r propto t0.5, but there are significant differences in different parts of the remnant: the bright northwestern part expands as r propto t0.35, whereas the rest of the remnant's expansion shows an expansion r propto t0.6. The latter is consistent with an explosion in which the outer part of the ejecta has a negative power law slope for density (ρ propto v-n) of n = 7, or with an exponential density profile [ρ propto exp (- v/ve) ]. The expansion parameter in the southern region, in conjunction with the shock radius, indicates a rather low value (<5 × 1050 erg) for the explosion energy of SN 1604 for a distance of 4 kpc. A higher explosion energy is consistent with the results if the distance is larger. The filament in the eastern part of the remnant, which is dominated by X-ray synchrotron radiation, seems to mark a region with a fast shock speed r propto t0.7, corresponding to a shock velocity of v = 4200 km s-1, for a distance to SN 1604 of 4 kpc. This is consistent with the idea that X-ray synchrotron emission requires shock velocities in excess of ~2000 km s-1. The X-ray-based expansion measurements reported are consistent with results based on optical and radio measurements but disagree with previous X-ray measurements based on ROSAT and Einstein observations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2008
- DOI:
- 10.1086/592375
- arXiv:
- arXiv:0803.4011
- Bibcode:
- 2008ApJ...689..231V
- Keywords:
-
- ISM: individual: Kepler's supernova;
- shock waves;
- supernova remnants;
- X-rays: ISM;
- Astrophysics
- E-Print:
- Accepted for publication in ApJ. This new version is the accepted version, which differs mainly in the discussion section