THE CLUSTERING OF QSOS AT LOW REDSHIFT

We have determined the correlation function, xi(r), for QSOs with z < 0.2 in the Einstein Extended Medium Sensitivity Survey (EMSS). At small scales we obtain a barely significant level of clustering, xi(< 10 h-1 Mpc) = 0.7 +/- 0.6. This amplitude of clustering is most consistent with the amplitude of QSO clustering derived at higher redshifts (z approximately 1.5) if the evolution of clustering is governed by a 'comoving' or biased model. The 'stable' model for the evolution of the QSO correlation function is marginally excluded by these observations, while models in which the QSO clusters are collapsing over this redshift interval are strongly excluded. At large scales. xi(r) > 100 h-1 Mpc, the correlation function is consistent with an unclustered population: xi (r) = 0.00 +/- 0.03.