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Register a new userThe M*-Mhalo relation at 0.08 < z < 1.53 in COSMOS: the role of AGN radio-mode feedback
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Eleni Vardoulaki Dr
Publication date
2021
fields
Physics
and research's language is
English
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In the current picture of cosmology and astrophysics, the formation and evolution of galaxies is closely linked to that of their dark matter haloes. The best representation of this galaxy-dark matter halo co-evolution is the M* - Mhalo relation. In this study we investigate how the radio-mode feedback from active galactic nuclei (AGN) affects the M* - Mhalo relation at redshifts 0.08 < z < 1.53. We use a set of 111 radio-selected AGN at 3 GHz VLA-COSMOS within the X-ray galaxy groups in the COSMOS field. We compare these results to the ones of 171 star-forming galaxies (SFGs), using the theoretical relation of Moster et al. (2013). We find that AGN agree within 1% with the Moster et al. (2013) relation, SFGs show an offset of 37%, suggesting that the radio-mode feedback from AGN at a median redshift of ~ 0.5 still plays a significant role in the M* - Mhalo relation.
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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 (L_1.4 < 1e24 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) cubed) 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.
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