Constraints on the distribution of supernova remnants with Galactocentric radius

TL;DR

This paper analyzes the distribution of supernova remnants in the Galaxy, considering observational biases and distance estimation challenges, and compares observed data with models to better understand their spatial distribution.

Contribution

It provides a new constraint on the Galactic distribution of SNRs by comparing observed distributions with models, highlighting a more centrally concentrated distribution.

Findings

The observed longitude distribution of bright SNRs aligns with a more centrally concentrated model.

Selection effects significantly influence the observed SNR distribution.

The best-fitting model differs from previous widely used distributions, favoring a more central concentration.

Abstract

Supernova remnants (SNRs) in the Galaxy are an important source of energy injection into the interstellar medium, and also of cosmic rays. Currently there are 294 known SNRs in the Galaxy, and their distribution with Galactocentric radius is of interest for various studies. Here I discuss some of the statistics of Galactic SNRs, including the observational selection effects that apply, and difficulties in obtaining distances for individual remnants from the `Sigma-D' relation. Comparison of the observed Galactic longitude distribution of a sample of bright Galactic SNRs -- which are not strongly affected by selection effects -- with those expected from models is used to constrain the Galactic distribution of SNRs. The best-fitting power-law/exponential model is more concentrated towards the Galactic centre than the widely used distribution obtained by Case & Bhattacharya (1998).