Sub-arcsecond radio continuum mapping in and around the spiral galaxy NGC3351 using MERLIN

TL;DR

This study used MERLIN to produce high-resolution radio maps of NGC3351, identifying 23 sources, including potential supernova remnants and background AGN, but not detecting individual supernovae or SNRs in the galaxy's center.

Contribution

First sub-arcsecond radio continuum mapping of NGC3351 with MERLIN, revealing detailed source distribution and insights into star formation and supernova activity.

Findings

23 radio sources detected, 6 within galaxy's isophote

Potential supernova remnant identified as a compact source

No individual supernovae or SNRs detected in the central region

Abstract

We report sub-arcsecond scale radio continuum observations of a field of 35 by 22 arcmin centred in NGC3351 obtained with the Multi-Element Radio Linked Interferometer Network (MERLIN). We found 23 radio sources in this field, 6 of which are projected within the D$_{25}$ isophote of the galaxy, and 3 are located inside the central 100 arcsec in radius. Two of these three are significantly extended, while the third one is relatively compact. This one is the only source with a previously detected counterpart at other wavelengths and could constitute the radio counterpart of a young supernova remnant. The other two are probably related to jets from a background AGN. We are not able to detect individual supernovae or SNRs in the central region ($r<600$ pc) of the galaxy. This could imply that the ionising populations of the circumnuclear star-forming regions (CNSFRs) are too young (less than a few Myr) to host supernovae. Also the diffusion length of the relativistic electrons in the ISM associated with the SN from previous events of star formation seems to be larger than our maximum resolution of 50 pc in radius. Detecting the thermal bremsstrahlung emission from the circumnuclear HII regions probably requires deeper observations.