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 _ { -0.24 } ^ { +0.33 } h ^ { -1 } \textrm { Mpc } and r _ { 0 } = 10.95 _ { -1.58 } ^ { +1.22 } h ^ { -1 } \textrm { 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 \sim 4.9 \times 10 ^ { 13 } h ^ { -1 } M _ { \odot } and \sim 1.9 \times 10 ^ { 12 } h ^ { -1 } M _ { \odot } , respectively .
Comparison with clustering studies of different radio source samples indicates that this mass scale of \gtrsim 1 \times 10 ^ { 13 } h ^ { -1 } M _ { \odot } 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 can not 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 .