We investigate the large-scale clustering of radio sources in the Green Bank and Parkes-MIT-NRAO 4.85 GHz surveys by measuring the angular two-point correlation function w ( \theta ) .
Excluding contaminated areas , the two surveys together cover 70 per cent of the whole sky .
We find both surveys to be reasonably complete above 50 mJy .
On the basis of previous studies , the radio sources are galaxies and radio-loud quasars lying at redshifts up to z \sim 4 , with a median redshift z \sim 1 .
This provides the opportunity to probe large-scale structures in a volume far larger than that within the reach of present optical and infrared surveys .
We detect a clustering signal w ( \theta ) \approx 0.01 for \theta = 1 \degr .
By assuming an evolving power-law spatial correlation function in comoving coordinates \xi ( r _ { c } ,z ) = ( r _ { c } / r _ { 0 } ) ^ { - \gamma } ( 1 + z ) ^ { \gamma - ( 3 + \epsilon ) } , where \gamma = 1.8 , and the redshift distribution N ( z ) of the radio galaxies , we constrain the r _ { 0 } – \epsilon parameter space .
For ‘ stable clustering ’ ( \epsilon = 0 ) , we find the correlation length r _ { 0 } \approx 18 h \hbox { $ { } ^ { -1 } $ } Mpc , larger than the value for nearby normal galaxies and comparable to the cluster-cluster correlation length .