The Virial Mass Function of Nearby SDSS Galaxy Clusters

Abstract

We present a new determination of the cluster mass function and velocity dispersion function in a volume $\sim 10^7{h}^3$Mpc${}^{-3}$ using the Fourth Data Release of the Sloan Digital Sky Survey (SDSS). We use the caustic technique to remove foreground and background galaxies. The cluster virial mass function agrees well with recent estimates from both X-ray observations and cluster richnesses. The mass function lies between those predicted by the First-Year and Three-Year WMAP data. We constrain the cosmological parameters ${\Omega }_m$ and ${\sigma }_8$ and find good agreement with WMAP and constraints from other techniques. With the CIRS mass function alone, we estimate ${\Omega }_m=0.24_{-0.09}^{+0.14}$ and ${\sigma }_8=0.92_{-0.19}^{+0.24}$, or ${\sigma }_8=0.84\pm$0.03 when holding ${\Omega }_m=0.3$ fixed. We also use the WMAP parameters as priors and constrain velocity segregation in clusters. Using the First and Third-Year results, we infer velocity segregation of ${\sigma }_{gxy}/{\sigma }_{DM}\approx 0.94\pm$0.05 or 1.28$\pm$0.06 respectively. We compare the velocity dispersion function of clusters to that of early-type galaxies and conclude that clusters comprise the high-velocity end of the velocity dispersion function of dark matter haloes. The evolution of cluster abundances provides constraints on dark energy models; the mass function presented here offers an important low redshift calibration benchmark.

22 pages, 11 figures, ApJ in press, revised figures

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Cited by in corpus (10)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Virial Scaling of Massive Dark Matter Halos: Why Clusters Prefer a High Normalization Cosmology
• LoCuSS: Comparison of Observed X-ray and Lensing Galaxy Cluster Scaling Relations with Simulations
• The X-Ray Concentration-Virial Mass Relation
• Strong lensing statistics and the power spectrum normalisation
• Testing cold dark matter with the low mass Tully-Fisher relation
• Scaling relations of the colour-detected cluster RzCS 052 at z=1.016 and of some other high redshift clusters
• WMAP5 and the Cluster Mass Function
• Reconstruction of Cluster Masses using Particle Based Lensing I: Application to Weak Lensing
• Detecting quasars at very high redshift with next generation X-ray telescopes