Active Galactic Nuclei signatures in Red Geyser galaxies from Gemini GMOS-IFU observations

TL;DR

This study uses Gemini GMOS-IFU observations to investigate the ionisation and kinematics of gas in Red Geyser galaxies, providing evidence for low-luminosity AGN activity and outflows in their central regions.

Contribution

First spatially resolved analysis of gas ionisation and kinematics in Red Geyser galaxies using GMOS-IFU data, confirming AGN presence and outflow features.

Findings

AGN ionisation indicated by emission-line ratios in all sources

Detection of outflows with misaligned velocity fields

Presence of faint AGN activity in some galaxies

Abstract

Red Geysers are quiescent galaxies with galactic scale ionised outflows, likely due to low-luminosity Active Galactic Nuclei (AGN). We used Gemini GMOS-IFU observations of the inner $\sim 1.0-3.0$ kpc of nine Red Geysers selected from the MaNGA survey to study the gas ionisation and kinematics. The emission-line ratios suggest the presence of Seyfert/LINER (Low Ionisation Nuclear Emission Region) nuclei in all sources. Two galaxies show H$\alpha$ equivalent width (H$\alpha$ EW) larger than 3 \AA (indicative of AGN ionisation) within an aperture 2.5 arcsec of diameter ($1.3-3.7$ kpc at the distance of galaxies) for MaNGA data, while with the higher resolution GMOS data, four galaxies present H$\alpha$ EW$>3$ \AA within an aperture equal to the angular resolution ($0.3-0.9$ kpc). For two objects with GMOS-IFU data, the H$\alpha$ EW is lower than 3 \AA but larger than 1.5 \AA, most probably due to a faint AGN. The spatially resolved electron density maps show values between $100-3000$ cm$^{-3}$ and are consistent with those determined in other studies. The large (MaNGA) and the nuclear scale (GMOS-IFU) gas velocity fields are misaligned, with a kinematic position angle difference between 12$^{\circ}$ and 60$^{\circ}$. The [NII]$\lambda$6583 emission-line profiles are asymmetrical, with blue wings on the redshifted side of the velocity field and red wings on the blueshifted side. Our results support previous indications that the gas in Red Geysers is ionised by an AGN, at least in their central region, with the presence of outflows, likely originating in a precessing accretion disc.