AAS 200th meeting, Albuquerque, NM, June 2002
Session 77. Large Scale Structure with the SDSS
Special Session Oral, Thursday, June 6, 2002, 10:00-11:30am, Ballroom A

## [77.06] SDSS Cluster Abundance and Cosmological Implications

J. Annis, M. Makler, S. Kent, S. Dodelson, J. Frieman (Fermilab), E. Sheldon, T. McKay (Michigan), N. Bahcall (Princeton), SDSS Collaboration

The SDSS is a very good cluster finding machine. The precise 5 color photometry allows photometric redshift techniques that revolutionize methods of finding clusters in the optical: projection on scales greater than delta-z = 0.05 is no longer a problem. A corollary is that cluster finders become both powerful group finders and powerful redshift estimators. The statistics of the SDSS allows several scaling relations to be constructed: Ngals, Lambda, \sigmavel, and weak lensing shear may be measured and related. In particular, we find that the cluster galaxy number function may be constructed from 0.05 \leq z \leq 0.5. By using SDSS calibrated halo occupational number distribution theories, the number functions may be predicted. The implied mass functions agree well with the measured SDSS velocity dispersion function, but do not suffer from the cosmic variance problems of all z < 0.1 measures.The number functions are quite sensitive to the mass power spectrum. In particular, the \sigma8/\Omegam degeneracy is broken, and constraints on \sigma8, the normalization of the power spectrum, may be placed. The other relevent cosmological parameters that affect the mass power spectrum are the dark matter mass density, the power spectrum index, and the neutrino mass density.

Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.