Publication Date:
2015-12-25
Description:
We present the first results from the KMOS ( K -band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASH z ), a VLT/KMOS integral-field spectroscopic (IFS) survey of z 0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN ( L 2–10 keV = 10 42 –10 45 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. L X 〉 6 x 10 43 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 KASH z 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.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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