Misc,
The KMOS AGN Survey at High redshift (KASHz): the prevalence and drivers of ionised outflows in the host galaxies of X-ray AGN
(2015)cite arxiv:1511.00008Comment: Re-submmited to MNRAS after addressing referee's comments. Main paper: 20 pages, 14 figures. Plus appendix.
Abstract
We present the first results from the KMOS AGN Survey at High redshift
(KASHz), a VLT/KMOS integral-field spectroscopic survey of z>0.6 AGN. We
present galaxy-integrated spectra of 89 X-ray AGN (Lx=10^42-10^45 erg/s), for
which we observed O III (z=1.1-1.7) or Halpha emission (z=0.6-1.1). The
targets have X-ray luminosities representative of the parent AGN population and
we explore the emission-line luminosities as a function of X-ray luminosity.
For the O III targets, ~50 per cent have ionised gas velocities indicative of
gas that is dominated by outflows and/or highly turbulent material (i.e.,
overall line-widths >~600 km/s). The most luminous half (i.e., Lx>6x10^43
erg/s) have a >~2 times higher incidence of such velocities. On the basis of
our results, we find no evidence that X-ray obscured AGN are more likely to
host extreme kinematics than unobscured AGN. Our KASHz sample has a
distribution of gas velocities that is consistent with a luminosity-matched
sample of z<0.4 AGN. This implies little evolution in the prevalence of ionised
outflows, for a fixed AGN luminosity, despite an order-of-magnitude decrease in
average star-formation rates over this redshift range. Furthermore, we compare
our Halpha targets to a redshift-matched sample of star-forming galaxies and
despite a similar distribution of Halpha luminosities and likely star-formation
rates, we find extreme ionised gas velocities are up to ~10x more prevalent in
the AGN-host galaxies. Our results reveal a high prevalence of extreme ionised
gas velocities in high-luminosity X-ray AGN and imply that the most powerful
ionised outflows in high-redshift galaxies are driven by AGN activity.
