THE GALAXY CLUSTERING CORRELATION LENGTH

The galaxy clustering correlation length r0 is studied using a variety of galaxy samples drawn from Huchra's CfA-I galaxy redshift catalogue (completeness limit m(B) less-than-or-equal-to 14.5) and the first Cf A-II slice (m(B) less-than-or-equal-to 15.5). Estimates of r0 depend o n the sample, and some samples show the well-known trend that r0 incre ases with sample depth. We study this phenomenon both in complete volu me limited samples, and in velocity limited samples with an a priori f ixed absolute magnitude limit M(com) = -18.5 + 5 log h, using a select ion function based on the sample luminosity function. The first sample is certainly affected by luminosity segregation. To isolate this effe ct we have studied samples with different depth and the same absolute magnitude limit. The effect of the luminosity segregation is clearly n oticed in biasing the value of r0. In the analysis of incomplete sampl es, if the luminosity function were a universal function, we would not expect strong luminosity dependent effects, therefore the observed va riability of r0 in these samples is mainly due to the weight large sca le inhomogeneities and the fact that we are not using a fair sample of the Universe. We have also studied the influence of the corrections p erformed by Einasto et al. (1984): galactic absorption and random pecu liar velocities in clusters.