The VLA-COSMOS 3 GHz Large Project: Cosmic evolution of radio AGN and implications for radio-mode feedback since z ~ 5

Smolčić, Vernesa and Novak, Mario and Delvecchio, I. and Ceraj, Lana and Bondi, M. and Delhaize, J. and Marchesi, S. and Murphy, E. and Schinnerer, E. and Vardoulaki, E. and Zamorani, G. (2017) The VLA-COSMOS 3 GHz Large Project: Cosmic evolution of radio AGN and implications for radio-mode feedback since z ~ 5. Astronomy and Astrophysics, 602. Art. No. A6-13. ISSN 0004-6361

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Based on a sample of over 1800 radio AGN at redshifts out to z ~ 5, which have typical stellar masses within ~3 × (1010 − 1011)M⊙, and 3 GHz radio data in the COSMOS field, we derived the 1.4 GHz radio luminosity functions for radio AGN (L1.4 GHz~ 1022 − 1027 W Hz-1) out to z ~ 5. We constrained the evolution of this population via continuous models of pure density and pure luminosity evolutions, and we found best-fit parametrizations of Φ∗ ∝ (1 + z)(2.00 ± 0.18) − (0.60 ± 0.14)z, and L∗ ∝ (1 + z)(2.88 ± 0.82) − (0.84 ± 0.34)z, respectively, with a turnover in number and luminosity densities of the population at z ≈ 1.5. We converted 1.4 GHz luminosity to kinetic luminosity taking uncertainties of the scaling relation used into account. We thereby derived the cosmic evolution of the kinetic luminosity density provided by the AGN and compared this luminosity density to the radio-mode AGN feedback assumed in the Semi-Analytic Galaxy Evolution (SAGE) model, i.e., to the redshift evolution of the central supermassive black hole accretion luminosity taken in the model as the source of heating that offsets the energy losses of the cooling, hot halo gas, and thereby limits further stellar mass growth of massive galaxies. We find that the kinetic luminosity exerted by our radio AGN may be high enough to balance the radiative cooling of the hot gas at each cosmic epoch since z ~ 5. However, although our findings support the idea of radio-mode AGN feedback as a cosmologically relevant process in massive galaxy formation, many simplifications in both the observational and semi-analytic approaches still remain and need to be resolved before robust conclusions can be reached.

Item Type: Article
Keywords: surveys, radio continuum: galaxies, galaxies: evolution
Date: 13 June 2017
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2017 ESO. Received 23 February 2017. Accepted 10 May 2017. Published online 13 June 2017. This research was funded by the European Union’s Seventh Frame-work programs under grant agreements 333654 (CIG, “AGN feedback”). V.S., M.N., I.D., and L.C. acknowledge support from the European Union’s Seventh Frame-work program under grant agreement 337595 (ERC Starting Grant, “CoSMass”). M.B. acknowledges support from the PRIN-INAF 2014. E.S. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 694343).
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Vernesa Smolčić
Date Deposited: 20 Nov 2017 09:08
Last Modified: 20 Nov 2017 09:08

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