A possible binary AGN in Mrk\,622?

TL;DR

This study reveals that Mrk 622 is a complex galaxy with a triple-peaked emission line structure, likely indicating a composite system of a single AGN and a binary AGN candidate, possibly due to a recent merger.

Contribution

The paper provides new optical spectroscopic evidence showing Mrk 622's triple-peaked emission lines and spatial separation, suggesting a composite AGN system with a potential binary AGN.

Findings

Mrk 622 exhibits triple-peaked narrow emission lines.

The blue and red components are spatially separated by ~76 pc.

The emission line components are consistent with AGN activity.

Abstract

Mrk\,622 is a Compton Thick AGN and a double-peaked narrow emission line galaxy, thus a dual AGN candidate. In this work, new optical long-slit spectroscopic observations clearly show that this object is rather a triple peaked narrow emission line galaxy, with both blue and red shifted narrow emission lines, as well as a much narrower emission line centred at the host galaxy systemic velocity. The average velocity offset between the blue and red shifted components is $\sim$500 km\,s$^{-1}$, which is producing the apparent double-peaked emission lines. These two components are in the loci of AGN in the Baldwin, Phillips \& Terlevich (BPT) diagrams and are found to be spatially separated by $\sim$76 pc. Analysis of the optical spatially resolved spectroscopic observations presented in this work favours that Mrk\,622 is a system consisting of a Composite AGN amidst a binary AGN candidate, likely the result of a recent merger. This notwithstanding, outflows from a starburst, or single AGN could also explain the triple nature of the emission lines.