The Cluster Mass Function from Early Sloan Digital Sky Survey Data: Cosmological Implications

The mass function of clusters of galaxies is determined from 400 deg² of early commissioning imaging data of the Sloan Digital Sky Survey; ~300 clusters in the redshift range z = 0. 1 - 0. 2 are used. Clusters are selected using two independent selection methods: a Matched Filter and a red-sequence color magnitude technique. The two methods yield consistent results. The cluster mass function is compared with large-scale cosmological simulations. We find a best-fit cluster normalization relation of sigma₈*omegaₘ⁰. 6 = 0. 33 +- 0. 03 (for 0. 1 ~= 0. 4) and low sigma₈ (=~ 2 sigma.