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The KMOS AGN Survey at High redshift (KASHz): The prevalence and drivers of ionized outflows in the host galaxies of X-ray AGN

Lookup NU author(s): Dr Christopher HarrisonORCiD


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© 2015 The Authors. Published by Oxford University Press. We present the first results from the KMOS (K-band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic (IFS) survey of z ≲ 0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (L2-10 keV = 1042-1045 erg s-1), for which we observed [OIII] (z ≈ 1.1-1.7) or Hα 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 [OIII] targets,≈50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall linewidths≲600 km s-1). The most luminous half (i.e. LX > 6 × 1043 erg s-1) 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 ofz<0.4 AGN. This implies little evolution in the prevalence of ionized 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 Hα targets to a redshift-matched sample of star-forming galaxies and despite a similar distribution of Hα luminosities and likely star formation rates, we find extreme ionized gas velocities are up to ≈10 times more prevalent in the AGN-host galaxies. Our results reveal a high prevalence of extreme ionized gas velocities in high-luminosity X-ray AGN and imply that the most powerful ionized outflows in high-redshift galaxies are driven by AGN activity.

Publication metadata

Author(s): Harrison CM, Alexander DM, Mullaney JR, Stott JP, Swinbank AM, Arumugam V, Bauer FE, Bower RG, Bunker AJ, Sharples RM

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2016

Volume: 456

Issue: 2

Pages: 1195-1220

Print publication date: 21/02/2016

Online publication date: 21/12/2015

Acceptance date: 17/11/2015

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press


DOI: 10.1093/mnras/stv2727


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