Imaging Spectroscopy of Ionized Gaseous Nebulae around Optically Faint AGNs at Redshift z similar to 2
2018
ASTROPHYSICAL JOURNAL
DOI
10.3847/1538-4357/aae156
We present Keck/OSIRIS laser guide-star assisted adaptive optics (LGSAO) integral-field spectroscopy of [O III].5007 nebular emission from 12 galaxies hosting optically faint (R = 20-25; nu L-nu similar to 10(44) - 10(46) erg s(-1)) active galactic nuclei (AGNs) at redshift z similar to 2-3. In combination with deep Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) 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 structures of these sources exhibit a wide range of morphologies, from compact, isolated point sources to double-AGN merging systems with extensive similar to 50 kpc tidal tails. One of the 12 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 AGNs; the [O III] velocity dispersions tend to be high (sigma = 100-500 km s(-1)), 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 AGNs 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.