Cosmic Evolution of Radio Selected Active Galactic Nuclei in the Cosmos Field

Abstract

We explore the cosmic evolution of radio AGN with low radio powers (L 1.4GHz 5 × 10 25 W Hz −1 ) out to z = 1.3 using to-date the largest sample of ∼ 600 low luminosity radio AGN at intermediate redshift drawn from the VLA-COSMOS survey. We derive the radio luminosity function for these AGN, and its evolution with cosmic time assuming two extreme cases: i) pure luminosity and ii) pure density evolution. The former and latter yield L * ∝ (1+z) 0.8±0.1 , and Φ * ∝ (1+z) 1.1±0.1 , respectively, both implying a fairly modest change in properties of low radio-power AGN since z = 1.3. We show that this is in stark contrast with the evolution of powerful (L 1.4GHz > 5 × 10 25 W Hz −1 ) radio AGN over the same cosmic time interval, constrained using the 3CRR, 6CE, and 7CRS radio surveys by Willott et al. (2001). We demonstrate that this can be explained through differences in black hole fueling and triggering mechanisms, and a dichotomy in host galaxy properties of weak and powerful AGN. Our findings suggest that high and low radio-power AGN activity is triggered in different stages during the formation of massive red galaxies. We show that weak radio AGN occur in the most massive galaxies already at z ∼ 1, and they may significantly contribute to the heating of their surrounding medium and thus inhibit gas accretion onto their host galaxies, as recently suggested for the 'radio mode' in cosmological models. 16 The 'radio mode' is defined here as given in Croton et al. (2006).

CONFIRMING THE EXISTENCE OF A QUIESCENT GALAXY POPULATION OUT TO z = 3: A STACKING ANALYSIS OF MID-, FAR-INFRARED, AND RADIO DATA

“…Our results indicate that low-luminosity radio AGNs may be widespread among massive QGs, reciprocating the fact that massive QGs are the preferential hosts for low-luminosity radio AGNs (e.g., Smolčić et al 2009;Baldi et al 2014), and that radio-mode AGN feedback gains importance at later cosmic epochs at z<1.5-2 (Croton et al 2006). The fact that we only detect AGN contribution at radio wavelengths but not 24 μm in massive QGs is interesting for two reasons: (1) this is consistent with the expectation for luminous AGNs that selection criteria at different wavelengths have only slight overlaps, i.e., most AGNs identified at one wavelength do not fulfill the selection criteria at other wavelengths (e.g., Lemaux et al 2014); (2) it indicates that only radio-mode feedback, but not (obscured) quasar-mode feedback, is at work in keeping the SF inefficient in massive QGs.…”

Galaxy formation in the Planck cosmology – I. Matching the observed evolution of star formation rates, colours and stellar masses

“…S24, a feature that we recently discovered in our dark matter merger trees moti- (Smolčić et al 2009) are shown as a light gray region.…”

“…The heating rate in the model is computed as Ω L mech = ηṀBHc 2 , while observationally it is derived from integrating the mechanical luminosity density function. This is obtained from the AGN monochromatic radio to mechanical power (see section 7.3 of Smolčić et al (2009)). The comparisons with observation presented in the main paper and in Paper II, in combination with Fig.…”

An overview of jet-mode AGN feedback and the prospects for studying its cosmic evolution with LOFAR

“…However, the only systematic study of jet-mode feedback in higher-redshift systems (out to z ∼ 0.5) was done by Hlavacek-Larrondo et al (2012) using the the MAssive Cluster Survey (MACS) sample and, as a result, is likely biased towards the most luminous cooling flow clusters. Instead, most studies of AGN feedback at high redshift (Lehmer et al 2007;Smolčić et al 2009;Danielson et al 2012;Ma et al 2013) rely on indirect methods of inferring AGN feedback powers, such as scaling relations between the jet power and the radio luminosity (e.g., Bîrzan et al 2008). These studies generally do not find any evidence for evolution in the feedback properties, suggesting that the jet-mode feedback starts to operate as early as 7 Gyr years after the Big Bang (z ∼ 1.3) and has not changed since then (see also Simpson et al 2013), thus maintaining the same approximate balance between AGN heating and radiative cooling as in the local universe (Best et al 2006).…”