The Mipsgal View of Supernova Remnants in the Galactic Plane

TL;DR

This study uses Spitzer Space Telescope data to detect and analyze Galactic supernova remnants in the mid-infrared, revealing their infrared properties, correlations with radio and X-ray emissions, and insights into their energy output.

Contribution

First mid-infrared survey of Galactic SNRs using MIPS, identifying 39 remnants and analyzing their multi-wavelength properties and emission ratios.

Findings

Detected 39 out of 121 SNRs in mid-infrared.

Infrared flux ratios show linear trends and correlations with radio emission.

Infrared energy emission is comparable to X-ray cooling.

Abstract

We report the detection of Galactic supernova remnants (SNRs) in the mid-infrared (at 24 and 70 {\mu}m), in the coordinate ranges 10 < l < 65 deg and 285 < l < 350 deg, |b| < 1 deg, using the Multiband Imaging Photometer (MIPS) aboard the Spitzer Space Telescope. We search for infrared counterparts to SNRs in Green's catalog and identify 39 out of 121, i.e., a detection rate of about 32%. Such a relatively low detection fraction is mainly due to confusion with nearby foreground/background sources and diffuse emission. The SNRs in our sample show a linear trend in [F8/F24] versus [F70/F24]. We compare their infrared fluxes with their corresponding radio flux at 1.4 GHz and find that most remnants have ratios of 70 {\mu}m to 1.4 GHz characteristic of SNRs (with the exception of a few which have ratios closer to those of H II regions). Furthermore, we retrieve a slope close to unity when correlating infrared (24 and 70 {\mu}m) with 1.4 GHz emission. Our survey is more successful in detecting remnants with bright X-ray emission, which we find is well correlated with the 24 {\mu}m morphology. Moreover, by comparing the power emitted in X-ray, infrared and radio, we conclude that the energy released in the infrared is comparable to the cooling in the X-ray range.