# Emission Measures and Emission-measure-weighted Temperatures of Shocked ISM and Ejecta in Supernova Remnants

## TL;DR

This paper develops models to connect supernova explosion parameters with observed X-ray properties of supernova remnants, enabling better inference of explosion characteristics from observations.

## Contribution

It introduces spherically symmetric hydrodynamic models and fitting formulae for emission measures and temperatures, integrated into the SNRPy code for practical application.

## Key findings

- Derived dimensionless emission measures and temperatures as functions of SNR age.
- Applied models to three historical supernova remnants: Kepler, Tycho, SN1006.
- Provided a tool for inferring explosion parameters from X-ray observations.

## Abstract

A goal of supernova remnant (SNR) evolution models is to relate fundamental parameters of a supernova (SN) explosion and progenitor star to the current state of its SNR. The SNR hot plasma is characterized by its observed X-ray spectrum, which yields electron temperature, emission measure and abundances. Depending on their brightness, the properties of the plasmas heated by the SNR forward shock, reverse shock or both can be measured. The current work utilizes models which are spherically symmetric. One dimensional hydrodynamic simulations are carried out for SNR evolution prior to onset of radiative losses. From these, we derive dimensionless emission measures and emission-measure-weighted temperatures, and we present fitting formulae for these quantities as functions of scaled SNR time. These models allow one to infer SNR explosion energy, circumstellar medium density, age, ejecta mass and ejecta density profile from SNR observations. The new results are incorporated into the SNR modelling code SNRPy. The code is demonstrated with application to three historical SNRs: Kepler, Tycho and SN1006.