## Abstract

The mass function of clusters of galaxies is determined from 400 deg ^{2} of early commissioning imaging data of the Sloan Digital Sky Survey using ∼300 clusters in the redshift range z = 0.1-0.2. 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 σ _{8}Ω_{m}^{0.6} = 0.33 ± 0.03 (for 0.1 ≲ Ω_{m} ≲ 0.4) or, equivalently, σ_{8} = (0.16/Ω_{m})^{0.6}. The amplitude of this relation is significantly lower than the previous canonical value, implying that either Ω_{m} is lower than previously expected (Ω_{m} = 0.16 if σ_{8} = 1) or σ_{8} is lower than expected (σ_{8} = 0.7 if Ω_{m} = 0.3). The shape of the cluster mass function partially breaks this classic degeneracy. We find best-fit parameters of Ω_{m} = 0.19±_{0.07} ^{0.08} and σ_{8} = 0.9±_{0.2} ^{0.3}. High values of Ω_{m} (≳ 0.4) and low σ_{8} (≲ 0.6) are excluded at ≳ 2 σ.

Original language | English (US) |
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Pages (from-to) | 182-190 |

Number of pages | 9 |

Journal | Astrophysical Journal |

Volume | 585 |

Issue number | 1 I |

DOIs | |

State | Published - Mar 1 2003 |

## All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science

## Keywords

- Cosmological parameters
- Cosmology: observations
- Cosmology: theory
- Dark matter
- Galaxies: clusters: general
- Large-scale structure of universe