Orateur
Description
Cassiopeia A (Cas A) is the youngest known galactic core-collapse supernova remnant (SNR) and is perhaps the best-studied SNR in X-rays. Cas A was observed at two different locations by XRISM, the X-Ray Imaging and Spectroscopy Mission, for more than a total of 350 ks. This rich dataset has revealed unprecedented details in elemental abundances, their dynamics, and plasma properties. In this talk, I will share the latest XRISM results on mapping the stellar ejecta kinematics and plasma properties of Cas A. I present the challenges faced during the analysis of high-resolution XRISM data, which required updates to atomic databases and Bayesian-based fitting methods. To this end, we developed UltraSPEX — a new tool integrating the nested sampling algorithm Ultranest with SPEX spectral fitting software, which offers unique computational advantages for fitting high-resolution XRISM/Resolve data.
