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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.

Harrison, C. M. and Alexander, D. M. and Mullaney, J. R. and Stott, J. P. and Swinbank, A. M. and Arumugam, V. and Bauer, F. E. and Bower, R. G. and Bunker, A. J. and Sharples, R. M. (2016) 'The KMOS AGN Survey at High redshift (KASHz) : the prevalence and drivers of ionized outflows in the host galaxies of X-ray AGN.', Monthly notices of the Royal Astronomical Society., 456 (2). pp. 1195-1220.


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 [O III] (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 [O III] targets, ≈50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall line widths ≳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 of z < 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.

Item Type:Article
Keywords:Galaxies: active - galaxies: evolution, Galaxies: kinematics and dynamics, Quasars: emission lines.
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Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:18 November 2015
Date deposited:25 January 2016
Date of first online publication:23 December 2015
Date first made open access:No date available

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