High spatial resolution X-ray spectroscopy of SNR Cassiopeia A with {\sl Chandra}

TL;DR

This study uses high-resolution Chandra X-ray spectroscopy to map the distribution of elements in Cassiopeia A, revealing jet structures and insights into the supernova's nucleosynthesis processes.

Contribution

It provides detailed spatial maps of element abundances and ionization states in Cassiopeia A, highlighting jet features and correlations among ejecta elements, advancing understanding of supernova explosion mechanisms.

Findings

Jet structures are visible in Si, S, and possibly Ca abundance maps.

Fe distribution is perpendicular to the jet, indicating different synthesis regions.

Correlations among element abundances suggest different nucleosynthesis processes.

Abstract

We present high spatial resolution X-ray spectroscopy of supernova remnant Cassiopeia A with the {\sl Chandra} observations. The X-ray emitting region of this remnant was divided into 38 $\times$ 34 pixels with a scale of 10$\arcsec$ $\times$ 10$\arcsec$ each. Spectra of 960 pixels were created and fitted with an absorbed two component non-equilibrium ionization model. With the spectral analysis results we obtained maps of absorbing column density, temperatures, ionization ages, and the abundances for Ne, Mg, Si, S, Ca and Fe. The Si, S and possibly Ca abundance maps show obviously jet structures, while Fe doesn't follow the jet but seems to be distributed perpendicular to it. In the range of about two orders of magnitude, the abundances of Si, S and Ca show tight correlations between each other, suggesting them to be ejecta from explosive O-burning and incomplete Si-burning. Meanwhile, Ne abundance is well correlated with that of Mg, indicating them to be the ashes of explosive C/Ne burning. The Fe abundance is positively correlated with that of Si when Si abundance is lower than 3 solar abundances, but a negative correlation appears when the Si abundance is higher. We suggest that such a two phase correlation is the results of different ways in which Fe is synthesized.