Abstract
We present two-dimensional numerical simulations of a model for Kepler's supernova remnant (SNR) carried out with the YGUAZU-A code. Following previous studies, we have assumed that the peculiar shape of this young remnant arises as a consequence of the interaction of the SNR blast wave with the bow shock formed by the wind of its high velocity progenitor. Furthermore, from our numerical results we have obtained synthetic X-ray emission maps, which can be directly compared with recent and previous observations of this SNR. Our models show that a nice fit with respect to the X-ray morphology and luminosity is obtained for a SN progenitor with mass-loss rate of 5 x 10(-5) M-circle dot yr(-1), an ambient medium density of 10(-2) cm(-3), an initial explosion energy of 8 x 10(50) ergs, and a total ejected mass within 1.4-2.5 M-circle dot. In our simulations, parameters typical of a young population progenitor have not been considered. This model also predicts a similar to 0.3% yearly decrease in the total X-ray luminosity, which is consistent with observed values. The parameters employed in our runs correspond to a Type Ia supernova. Based on our simulations, we find that the expansion rate increases after the SNR blast wave overruns the bow shock, and we discuss whether this can explain the observed difference between the expansion rates measured from sequences of radio and X-ray images. (Less)
Highlights
Kepler’s supernova remnant (SNR) exploded 400 yr ago and is one of the few so-called historical SNRs
The present manuscript is organized in the following way: in x 2 we describe the main features of Bandiera’s scenario; the initial conditions for numerical simulations and the overall features of the YGUAZU -A code are given in x 2.1; the simulation of the X-ray emission is discussed in x 2.2; the numerical results and comparison with observations are given in x 3; and in x 4 we present our summary and conclusions
Our numerical simulations have two stages: the first one consists of generating a cometary or bowshock structure produced by the interaction of the isotropic stellar wind of the progenitor with the plane-parallel ISM wind and the second one is the evolution of a SNR expanding into this anisotropic medium
Summary
Kepler’s supernova remnant (SNR) exploded 400 yr ago and is one of the few so-called historical SNRs. An emission band crosses the disk of the SNR from NW to SE, which might arise from material on the front and back sides of the shell seen in projection (Blair 2005). Combining Very Large Array (VLA) 6 and 20 cm observations, DeLaney et al (2002) found variations of the spectral index around the remnant, with the steepest indices ($À0.85) at the NW ear and the flattest ones ($À0.65) at the northern bright arc. Spectral differences are found in X-rays; while most of the X-ray emission is dominated by lines from Si, S, Ar, Ca, and Fe (Becker et al 1980; Kinugasa & Tsunemi 1999), recent XMM-Newton (Cassam-Chenaı et al 2004) and Chandra (Bamba et al 2005) observations have revealed nonthermal thin filaments marking the outer edge of the SNR. While in recent years there was a general agreement in favor of a core-collapse event rather than a Type Ia, as was originally believed (Baade 1943), the abundances recently determined, based on XMM-Newton data (CassamChenaı et al 2004), can be indicative of a Type Ia event
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