Near-Infrared Coronal Line Observations of Dwarf Galaxies hosting AGN-driven Outflows

TL;DR

This study uses near-infrared spectroscopy to confirm AGN activity and galaxy-wide outflows in dwarf galaxies, revealing that coronal line emissions are effective indicators of AGN-driven outflows in low-mass galaxies.

Contribution

It provides new evidence of AGN-driven outflows in dwarf galaxies through coronal line detection and kinematic analysis, expanding understanding of AGN feedback in low-mass systems.

Findings

55% of dwarf galaxies show coronal line detections confirming AGN presence.

Outflow velocities in [Si VI] are generally faster than in [O III].

Galaxies with faster [O III] outflows also have higher [Si VI] luminosity.

Abstract

We have obtained Keck NIR spectroscopy of a sample of nine M$_\star$ $<$ 10$^{10}$ M$_\odot$ dwarf galaxies to confirm AGN activity and the presence of galaxy-wide, AGN-driven outflows through coronal line (CL) emission. We find strong CL detections in 5/9 galaxies (55$\%$) with line ratios incompatible with shocks, confirming the presence of AGN in these galaxies. Similar CL detection rates are found in larger samples of more massive galaxies hosting type 1 and 2 AGN. We investigate the connection between the CLs and galaxy-wide outflows by analyzing the kinematics of the CL region, as well as the scaling of gas velocity with ionization potential of different CLs. In addition, using complementary Keck KCWI observations of these objects, we find that the outflow velocities measured in [Si VI] are generally faster than those seen in [O III]. The galaxies with the fastest outflows seen in [O III] also have the highest [Si VI] luminosity. The lack of $J$-band CN absorption features, which are often associated with younger stellar populations, provides further evidence that these outflows are driven by AGN in low mass galaxies.