3D Spectroscopic Study of the Line Emitting Regions of Mrk 493

TL;DR

This study uses 3D spectroscopy to analyze the emission regions of Mrk 493, revealing complex line components, a circum-nuclear star-forming ring, and the presence of HII regions in its nucleus.

Contribution

First 3D spectroscopic analysis of Mrk 493 revealing detailed structure of emission lines and nuclear regions, including star-forming rings and non-BLR Fe II emission origins.

Findings

Detection of multiple emission line components with different velocities.

Identification of a circum-nuclear star-forming ring.

Presence of HII regions in the NLR, not a typical Seyfert 1 nucleus.

Abstract

We report the results of 3D spectroscopic observations of Mrk 493 (NLS1 galaxy) with the integral-field spectrograph MPFS of the SAO RAS 6-m telescope. The difference in the slope of the optical continuum emission intensity across the nucleus part and an extensive continuum emission region} is detected. The emission in lines (H$\alpha$, H$\beta$, [OIII], etc.) coincides with a composite nuclear region: an AGN plus a circum-nuclear star-forming ring observed in the HST UV/optical images. The [SII] emission region tends to be up to 1kpc around the center. The H$\alpha$ and H$\beta$ could be decomposed into three components (broad $\sim$ 2000 km/s. intermediate $\sim$ 700 km/s and narrow $\sim$ 250 km/s). We found that width ($\sim$ 750 km/s) of the Fe II lines correspond to the intermediate component, that may indicate a non-BLR origin of the Fe II lines, or that a large fraction of the Fe II emission arise in the outher parts of the BLR. The weak broad component detected in the H$\alpha$, H$\beta$ and He$\lambda$4686 may come from the unresolved central BLR, but also partly produced by violent starburst in the circum-nuclear ring. Moreover, diagnostic diagrams clearly show presence of the HII regions (not a Sy 1 nucleus) in the NLR of Mrk 493.