Mon. Not. R. Astron. Soc., 445, 955-969 (2014/November-3)
The cosmic evolution of radio-AGN feedback to z = 1.
BEST P.N., KER L.M., SIMPSON C., RIGBY E.E. and SABATER J.
Abstract (from CDS):
This paper presents the first measurement of the radio luminosity function of `jet-mode' (radiatively inefficient) radio-AGN out to z = 1, in order to investigate the cosmic evolution of radio-AGN feedback. Eight radio source samples are combined to produce a catalogue of 211 radio-loud AGN with 0.5 < z < 1.0, which are spectroscopically classified into jet-mode and radiative-mode (radiatively efficient) AGN classes. Comparing with large samples of local radio-AGN from the Sloan Digital Sky Survey, the cosmic evolution of the radio luminosity function of each radio-AGN class is independently derived. Radiative-mode radio-AGN show an order of magnitude increase in space density out to z ~ 1 at all luminosities, consistent with these AGN being fuelled by cold gas. In contrast, the space density of jet-mode radio-AGN decreases with increasing redshift at low radio luminosities (L1.4GHz ≲ 1024 W/ Hz) but increases at higher radio luminosities. Simple models are developed to explain the observed evolution. In the best-fitting models, the characteristic space density of jet-mode AGN declines with redshift in accordance with the declining space density of massive quiescent galaxies, which fuel them via cooling of gas in their hot haloes. A time delay of 1.5-2 Gyr may be present between the quenching of star formation and the onset of jet-mode radio-AGN activity. The behaviour at higher radio luminosities can be explained either by an increasing characteristic luminosity of jet-mode radio-AGN activity with redshift (roughly as (1 + z)3) or if the jet-mode radio-AGN population also includes some contribution of cold-gas-fuelled sources seen at a time when their accretion rate was low. Higher redshifts measurements would distinguish between these possibilities.
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)
accretion, accretion discs - galaxies: active - galaxies: evolution - galaxies: jets - radio continuum: galaxies
VizieR on-line data:
<Available at CDS (J/MNRAS/445/955): tablea1.dat>
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