Detailed study of the microwave emission of the supernova remnant 3C 396

TL;DR

This study comprehensively observes supernova remnant 3C 396 across multiple microwave frequencies, finding a dominant synchrotron emission with no evidence of anomalous microwave emission, and analyzing its correlation with infrared data.

Contribution

It provides detailed microwave observations of 3C 396 across several frequencies and investigates the emission mechanisms and their relation to infrared emission.

Findings

Spectral energy distribution follows a single power law with spectral index -0.364.

No evidence of anomalous microwave emission from 3C 396.

Polarised emission consistent with synchrotron radiation.

Abstract

We have observed the supernova remnant 3C~396 in the microwave region using the Parkes 64-m telescope. Observations have been made at 8.4 GHz, 13.5 GHz, and 18.6 GHz and in polarisation at 21.5 GHz. We have used data from several other observatories, including previously unpublished observations performed by the Green Bank Telescope at 31.2 GHz, to investigate the nature of the microwave emission of 3C 396. Results show a spectral energy distribution dominated by a single component power law emission with $\alpha=(-0.364 \pm 0.017)$. Data do not favour the presence of anomalous microwave emission coming from the source. Polarised emission at 21.5 GHz is consistent with synchrotron-dominated emission. We present microwave maps and correlate them with infrared (IR) maps in order to characterise the interplay between thermal dust and microwave emission. IR vs. microwave TT plots reveal poor correlation between mid-infrared and microwave emission from the core of the source. On the other hand, a correlation is detected in the tail emission of the outer shell of 3C 396, which could be ascribed to Galactic contamination.