The XMM-XXL Survey spans two fields of 25 deg ^ { 2 } each observed for more than 6Ms with XMM , which provided a sample of tens of thousands of point sources with a flux limit of \sim 2.2 \times 10 ^ { -15 } and \sim 1.4 \times 10 ^ { -14 } erg s ^ { -1 } cm ^ { 2 } , corresponding to 50 % of the area curve , in the soft band and hard band , respectively .
In this paper we present the spatial clustering properties of \sim 3100 and \sim 1900 X-ray active galactic nuclei ( AGNs ) in the 0.5–2 and 2–10 keV bands , respectively , which have been spectroscopically observed with the AAOmega facility .
This sample is 90 % redshift complete down to an optical magnitude limit of r \lesssim 21.8 .
The sources span the redshift interval 0 < z < 5.2 , although in the current analysis we limit our samples to z \leq 3 , with corresponding sample median values of \bar { z } \simeq 0.96 and 0.79 for the soft band and hard band , respectively .
We employ the projected two-point correlation function to infer the spatial clustering and find a correlation length r _ { 0 } = 7.0 ( \pm 0.34 ) and 6.42 ( \pm 0.42 ) h ^ { -1 } Mpc , respectively , for the soft- and hard-band detected sources with a slope for both cases of \gamma = 1.44 ( \pm 0.1 ) .
The power-law clustering was detected within comoving separations of 1 and \sim 25 h ^ { -1 } Mpc .
These results , as well as those derived in two separate redshift ranges , provide bias factors of the corresponding AGN host dark matter halos that are consistent with a halo mass of \log _ { 10 } [ M _ { h } / ( h ^ { -1 } M _ { \odot } ) ] = 13.04 \pm 0.06 , confirming the results of most recent studies based on smaller X-ray AGN samples .