Probing the radio loud/quiet AGN dichotomy with quasar clustering

Abstract

We investigate the clustering properties of 45441 radio-quiet quasars (RQQs) and 3493 radio-loud quasars (RLQs) drawn from a joint use of the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at 20 cm (FIRST) surveys in the range 0.3 < z < 2.3. This large spectroscopic quasar sample allow us to investigate the clustering signal dependence on radio-loudness and black hole (BH) virial mass. We find that RLQs are clustered more strongly than RQQs in all the redshift bins considered. We find a real-space correlation length of r 0 = 6.59 +0.33 −0.24 h −1 Mpc and r 0 = 10.95 +1.22 −1.58 h −1 Mpc for RQQs and RLQs, respectively, for the full redshift range. This implies that RLQs are found in more massive host haloes than RQQs in our samples, with mean host halo masses of ∼ 4.9 × 10 13 h −1 M and ∼ 1.9 × 10 12 h −1 M , respectively. Comparison with clustering studies of different radio source samples indicates that this mass scale of 1 × 10 13 h −1 M is characteristic for the bright radio-population, which corresponds to the typical mass of galaxy groups and galaxy clusters. The similarity we find in correlation lengths and host halo masses for RLQs, radio galaxies and flat-spectrum radio quasars agrees with orientation-driven unification models. Additionally, the clustering signal shows a dependence on black hole (BH) mass, with the quasars powered by the most massive BHs clustering more strongly than quasars having less massive BHs. We suggest that the current virial BH mass estimates may be a valid BH proxies for studying quasar clustering. We compare our results to a previous theoretical model that assumes that quasar activity is driven by cold accretion via mergers of gas-rich galaxies. While the model can explain the bias and halo masses for RQQs, it cannot reproduce the higher bias and host halo masses for RLQs. We argue that other BH properties such as BH spin, environment, magnetic field configuration, and accretion physics must be considered to fully understand the origin of radio-emission in quasars and its relation to the higher clustering.

The role of galaxy mass on AGN emission: a view from the VANDELS survey

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VLT/SINFONI study of black hole growth in high-redshift radio-loud quasars from the CARLA survey

“…This correlation between radio-loudness and BH mass suggests that the properties of the SMBH play some role in the formation of the jet (Gu et al 2001;Lacy et al 2001;Chiaberge et al 2015). Moreover, radio-loud AGN are more strongly clustered than radio-quiet AGN, suggesting that they are found in more massive halos (Overzier et al 2003;Retana-Montenegro & Röttgering 2017). This implies that radio-loudness alone is already a good indicator of the BH mass in any quasar sample (Retana-Montenegro & Röttgering 2017).…”

AGN dichotomy beyond radio loudness: a Gaussian mixture model analysis

“…Some au-thors considered quasar luminosity evolution when searching for dichotomy (Singal et al 2013). Retana-Montenegro & Röttgering (2017) investigated the existence of quasars' spatial clustering and detected significant correlations with redshift for RL quasars at z ≤ 2.3, which could provide valuable information about quasar evolution. The dichotomy in quasars seems to be a general property, and not only a consequence of the radio emission.…”