Clustering properties of two samples of X-ray selected AGNs are compared with IR/Optical galactic samples .
These are the Einstein Observatory Extended Medium Sensitivity Survey : EMSS ( Maccacaro it et al .
1991 ) , with flux limit of > 3.25 ( 10 ^ { -14 } ) erg cm ^ { -2 } sec ^ { -1 } ( 0.5-2.0 keV ) , redshifts up to 2.83 and a sky coverage of 778 deg ^ { 2 } ; and an all sky sample of 654 ROSAT detected radio quasars ( Brinkmann et al . 1997 ) , with a uniform flux limit of a few ( 10 ^ { -13 } ) erg cm ^ { -2 } sec ^ { -1 } ( 0.1-2.4 keV ) and redshifts up to 3.886 .
The cosmological dipole moment is calculated for these samples , yielding the values of b \Omega _ { o } ^ { -0.6 } ( where b is the bias parameter , and \Omega _ { o } is the present value of the cosmological density parameter ) .
We find this factor to be 0.68 \pm 0.22 for the EMSS sample , and 1.02 \pm 0.014 for the quasars sample .
Comparing these values with that of the IRAS 1.2 Jy sample ( 1.95 \pm 0.096 ) , suggests that these AGNs are less clustered than the IRAS galaxies .
For each sample there is a depth at which the amplitude of the dipole growth curve saturates .
This convergence radius ( R _ { conv } ) is found to be \sim 300 - 400 h ^ { -1 } Mpc for the EMSS sample and \sim 450 - 500 h ^ { -1 } Mpc for the ROSAT detected quasars sample , which suggests that X-ray AGNs have a much deeper contribution to the Local Group ( LG ) motion compared to the galaxy and cluster samples .
Also the maximum amplitudes at saturation are found to be ~ { } 405 \pm 103 km/sec for the EMSS AGNs and ~ { } 617 \pm 8 km/sec for the quasar sample , which suggests that the lower the flux limit of the sample ( ie .
the more sensitive the sample ) , the lower the maximum amplitude at the region of saturation , therefore the less clustered the sample .
Using the properties of the angular and spatial correlation functions for these samples , we find : b _ { IRAS } / b _ { quasars } = 3.61 \pm 2.7 ; b _ { IRAS } / b _ { EMSS } = 8.46 \pm 6.4 and b _ { quasars } / b _ { EMSS } = 2.35 \pm 0.2 .
Using Chi-squared minimisation , we have fitted the angular correlation functions using the standard power law model of the form : W ( \theta ) = A \theta ^ { - \delta } , and the spatial correlation functions using the power law model of the form : \xi ( r ) = ( r / r _ { 0 } ) ^ { - \gamma } .
For the angular correlation functions , we find A \sim 0.6 for the AGN auto-correlations and A \sim 0.2 - 0.3 for the AGN-IRAS galaxy cross-correlations .
Also \delta is found to be ~ { } 0.8 - 1.1 .
In the spatial correlation analysis , we find r _ { o } \sim 3.5 - 5.1 h ^ { -1 } Mpc and \gamma \sim 1.4 - 1.7 .
The bias factor resulting from the IR / Optical galaxies may not be the true representative of this parameter , due to the local nature of those samples , whereas AGN samples are deep/far enough to give a more accurate value of this parameter .