Gas-Phase metallicity for the Seyfert galaxy NGC 7130

TL;DR

This study reveals a positive radial metallicity gradient in the AGN-ionized region of NGC 7130, suggesting AGN activity may transport metals outward, providing insights into galaxy evolution and gas flow mechanisms.

Contribution

It presents the first detection of a positive metallicity gradient in the AGN component of a Seyfert galaxy, highlighting the role of AGN-driven metal redistribution.

Findings

Positive metallicity gradient found only in AGN ionized gas

Metal transport from galaxy center to outskirts inferred

Uses advanced MUSE observations and strong-line diagnostics

Abstract

Metallicity measurements in galaxies can give valuable clues about galaxy evolution. One of the mechanisms postulated for metallicity redistribution in galaxies is gas flows induced by AGN, but the details of this process remain elusive. We report the discovery of a positive radial gradient in the gas-phase metallicity of the narrow line region of the Seyfert 2 galaxy NGC 7130, which is not found when considering the star-forming components in the galaxy disk. To determine gas-phase metallicities for each kinematic component, we use both active galactic nuclei (AGN) and star-forming (SF) strong-line abundance relations, as well as BPT diagnostic diagrams. These relations involve sensitive strong emission lines, namely [OIII]5007, [NII]6584, H$\alpha$, H$\beta$, [SII]6716, and [SII]6731, observed with the adaptive-optics-assisted mode of the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT). The presence of a positive radial metallicity gradient only in the AGN ionized component suggests that metals may be transported from central areas to its purlieus by AGN activity.