Imaging Spectroscopy of Ionized Gaseous Nebulae around Optically Faint AGN at Redshift z ~ 2

TL;DR

This study uses advanced spectroscopy to analyze ionized gas around faint AGN at high redshift, revealing diverse galaxy morphologies, evidence of large-scale gas flows, and properties consistent with near-Eddington accretion.

Contribution

First detailed integral field spectroscopy of faint high-redshift AGN nebulae, linking morphology, gas flows, and ionization properties to AGN activity.

Findings

Diverse galaxy morphologies from compact to merging systems.

Evidence of large-scale gas flows photoionized by AGN.

AGN radiate near their Eddington limit, with nebula sizes scaling with luminosity.

Abstract

We present Keck/OSIRIS laser guide-star assisted adaptive optics (LGSAO) integral field spectroscopy of [O III] 5007 Angstrom nebular emission from twelve galaxies hosting optically faint (R = 20 - 25; nuLnu ~ 10^44 -10^46 erg/s) active galactic nuclei (AGN) at redshift z ~ 2 - 3. In combination with deep Hubble Space Telescope Wide Field Camera 3 rest-frame optical imaging, Keck/MOSFIRE rest-optical spectroscopy, and Keck/KCWI rest-UV integral field spectroscopy we demonstrate that both the continuum and emission-line structure of these sources exhibit a wide range of morphologies from compact isolated point sources to double-AGN merging systems with extensive ~ 50 kpc tidal tails. One of the twelve galaxies previously known to exhibit a proximate damped LyA system coincident in redshift with the galaxy shows evidence for both an extended [O III] narrow-line emission region and spatially offset LyA emission (with morphologically distinct blueshifted and redshifted components) indicative of large scale gas flows photoionized by the central AGN. We do not find widespread evidence of star formation in the host galaxies surrounding these AGN; the [O III] velocity dispersions tend to be high (sigma = 100 - 500 km/s), the continuum morphologies are much more compact than a mass-matched star forming comparison sample, and the diagnostic nebular emission line ratios are dominated by an AGN-like ionizing spectrum. The sample is most consistent with a population of AGN that radiate at approximately their Eddington limit and photoionize extended [O III] nebulae whose characteristic sizes scale approximately as the square root of the AGN luminosity.