The VLA-COSMOS 3 GHz Large Project: Star formation properties and radio luminosity functions of AGN with moderate-to-high radiative luminosities out to z∼6

Ceraj, Lana and Smolčić, Vernesa and Delvecchio, Ivan and Novak, Mladen and Zamorani, Giovanni and Delhaize, Jacinta and Schinnerer, Eva and Vardoulaki, Eleni and Herrera Ruiz, Noelia (2018) The VLA-COSMOS 3 GHz Large Project: Star formation properties and radio luminosity functions of AGN with moderate-to-high radiative luminosities out to z∼6. Astronomy and Astrophysics, 620. A192. ISSN 0004-6361

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Abstract

We have studied a sample of 1604 moderate-to-high radiative luminosity active galactic nuclei (HLAGN) selected at 3 GHz within the VLA-COSMOS 3 GHz Large Project. These were classified by combining multiple AGN diagnostics: X-ray data, mid-infrared data and broadband spectral energy distribution fitting. We decomposed the total radio 1.4 GHz luminosity (L_1.4GHz, TOT) into the emission originating from star formation and AGN activity by measuring the excess in L_1.4GHz, TOT relative to the infrared-radio correlation of star-forming galaxies. To quantify the excess, for each source we calculated the AGN fraction (f_AGN) defined as the fractional contribution of AGN activity to L_1.4GHz, TOT. The majority of the HLAGN, (68.0+-1.5)%, are dominated by star-forming processes(f_AGN<=0.5), while (32.0+-1.5)% are dominated by AGN-related radio emission (0.5 < f_AGN <=1).We used the AGN-related 1.4 GHz emission to derive the 1.4 GHz AGN luminosity functions of HLAGN. By assuming pure density and pure luminosity evolution models we constrained their cosmic evolution out to z~6, finding Phi(z)* ~(1+z)^((2.64+-0.10)+(-0.61+-0.04)z) and L*(z)~(1+z)^((3.97+-0.15)+(-0.92+-0.06)z).These evolutionary laws show that the number and luminosity density of HLAGN increased from higher redshifts (z~6) up to a maximum in the redshift range 1 < z < 2.5, followed by a decline toward local values. By scaling the 1.4 GHz AGN luminosity to kinetic luminosity using the standard conversion, we estimate the kinetic luminosity density as a function of redshift. We compare our result to the semi-analytic models of radio mode feedback, and find that this feedback could have played an important role in the context of AGN-host co-evolution in HLAGN which shows evidence of AGN-related radio emission (f_AGN > 0).

Item Type: Article
Keywords: galaxies: active, galaxies: evolution, galaxies: high-redshift, galaxies: star formation
Date: 2018
Number of Pages: 19
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © ESO 2018. Received: 24 July 2018; Accepted: 30 October 2018; Published online: 17 December 2018.
Divisions: Faculty of Science > Department of Physics
Project code: EK-FP7-337595
Publisher: EDP Sciences
Depositing User: Vernesa Smolčić
Date Deposited: 14 Apr 2019 18:23
Last Modified: 14 Apr 2019 18:29
URI: http://digre.pmf.unizg.hr/id/eprint/5922

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