Supernova remnant properties and luminosity functions in NGC 7793 using MUSE IFS

Abstract

ABSTRACT In this study, we use MUSE Integral Field Spectroscopy (IFS), along with multiline diagnostics, for the optical identification of supernova remnants (SNRs) in the galaxy NGC 7793. We find in total 238 SNR candidates, 225 of them new identifications, increasing significantly the number of known SNRs in this galaxy. The velocity dispersion of the candidate SNRs was calculated, giving a mean value of $\rm 27\, km\, s^{-1}$. We construct the H $\rm {\alpha }$, [S ii], [O iii], and [S ii]–H $\rm {\alpha }$ luminosity functions, and for the first time, the [N ii], [N iI]–H $\rm {\alpha }$, [N ii]–[S ii], [O iii]–[S ii], and [O iii]–[N ii] luminosity functions of the candidate SNRs. Shock models, along with the observed multiline information were used, in order to estimate shock velocities. The $\rm \sim 65{{\ \rm per\ cent}}$ of the SNRs present velocities < 300 $\rm km\, s^{-1}$. There is a clear correlation between shock velocity and [O iii]/H $\rm {\beta }$ ratio, and a less clear but still evident correlation in the relation between shock velocity and the [S ii]/H $\rm {\alpha }$, [N ii]/H $\rm {\alpha }$ ratios. We also use the [S ii]6716/31 ratio of the SNR candidates to calculate their post-shock density, assuming different temperatures. The median value of the density of our sample is $\rm \sim 80\, cm^{-3}$, for a temperature of $\rm T = 10^4\, K$. No correlation between shock velocity and density, or density and SNRs with [S ii]/H $\rm {\alpha }$ > 0.4 and [S ii]/H $\rm {\alpha }$ < 0.4 is observed.