Near-infrared Coronal Line Observations of Dwarf Galaxies Hosting AGN-driven Outflows

Abstract

Abstract We have obtained Keck near-infrared spectroscopy of a sample of nine M ⋆ < 1010 M ⊙ dwarf galaxies to confirm active galactic nuclei (AGNs) 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 AGNs in these galaxies. Similar CL detection rates are found in larger samples of more massive galaxies hosting type 1 and 2 AGNs. 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 Cosmic Web Imager 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 AGNs in low-mass galaxies.