Following Rozo, it seems that Universe try to hide some of his properties: indeed results about weight of galaxies clusters appear to depend on measurement technique. In order to verify the assertion, I find reserach's page at KICP and here the links to yout last preprints (published in 2011). Here the abstract:
Extrinsic Sources of Scatter in the Richness-Mass Relation of Galaxy Clusters with Eli Rykoff, Benjamin Koester, Brian Nord, Hao-Yi Wu, August Evrard, Risa Wechsler
Maximizing the utility of upcoming photometric cluster surveys requires a thorough understanding of the richness-mass relation of galaxy clusters. We use Monte Carlo simulations to study the impact of various sources of observational scatter on this relation. Cluster ellipticity, photometric errors, photometric redshift errors, and cluster-to-cluster variations in the properties of red-sequence galaxies contribute negligible noise. Miscentering, however, can be important, and likely contributes to the scatter in the richness-mass relation of galaxy maxBCG clusters at the low mass end, where centering is more difficult. We also investigate the impact of projection effects under several empirically motivated assumptions about cluster environments. Using SDSS data and the maxBCG cluster catalog, we demonstrate that variations in cluster environments can rarely ($\approx$ 1% - 5% of the time) result in significant richness boosts. Due to the steepness of the mass/richness function, the corresponding fraction of optically selected clusters that suffer from these projection effects is $\approx$ 5% - 15%. We expect these numbers to be generic in magnitude, but a precise determination requires detailed, survey-specific modeling.Cosmological Constraints from Galaxy Clustering and the Mass-to-Number Ratio of Galaxy Clusters with Jeremy L. Tinker, Erin S. Sheldon, Risa H. Wechsler, Matthew R. Becker, Ying Zu, David H. Weinberg, Idit Zehavi, Michael Blanton, Michael Busha, Benjamin P. Koester
We place constraints on the average density ($\Omega_m$) and clustering amplitude ($\sigma_8$) of matter using a combination of two measurements from the Sloan Digital Sky Survey: the galaxy two-point correlation function, $w_p$, and the mass-to-galaxy-number ratio within galaxy clusters, $M/N$, analogous to cluster $M/L$ ratios. Our $w_p$ measurements are obtained from DR7 while the sample of clusters is the maxBCG sample, with cluster masses derived from weak gravitational lensing. We construct non-linear galaxy bias models using the Halo Occupation Distribution (HOD) to fit both $w_p$ and $M/N$ for different cosmological parameters. HOD models that match the same two-point clustering predict different numbers of galaxies in massive halos when $\Omega_m$ or $\sigma_8$ is varied, thereby breaking the degeneracy between cosmology and bias. We demonstrate that this technique yields constraints that are consistent and competitive with current results from cluster abundance studies, even though this technique does not use abundance information. Using $w_p$ and $M/N$ alone, we find $\Omega_m^0.5 \cdot \sigma_8=0.465 \pm 0.026$, with individual constraints of $\Omega_m=0.29 \pm 0.03$ and $\sigma_8=0.85 \pm 0.06$. Combined with current CMB data, these constraints are $\Omega_m=0.290 \pm 0.016$ and $\sigma_8=0.826 \pm 0.020$. All errors are $1-\sigma$. The systematic uncertainties that the $M/N$ technique are most sensitive to are the amplitude of the bias function of dark matter halos and the possibility of redshift evolution between the SDSS Main sample and the maxBCG sample. Our derived constraints are insensitive to the current level of uncertainties in the halo mass function and in the mass-richness relation of clusters and its scatter, making the $M/N$ technique complementary to cluster abundances as a method for constraining cosmology with future galaxy surveys.The Sunyaev-Zeldovich Signal of the maxBCG SDSS Galaxy Clusters in WMAP with Patrick Draper, Scott Dodelson, Jiangang Hao
The Planck Collaboration measured the Sunyaev-Zel'dovich (SZ) decrement of optically selected clusters from the Sloan Digital Sky Survey, finding that it falls significantly below expectations based on existing mass calibration of the maxBCG galaxy clusters. Resolving this tension requires either the data to go up, or the theoretical expectations to come down. Here, we use data from the Wilkinson Microwave Anisotropy Probe (WMAP) to perform an independent estimate of the SZ decrement of maxBCG clusters. The recovered signal is consistent with that obtained using Planck, though with larger error bars due to WMAP's larger beam size and smaller frequency range. Nevertheless, this detection serves as an independent confirmation of the magnitude of the effect, and demonstrates that the observed discrepancy must be theoretical in origin.I don't know if Rozo speaks about one of the previous preprint, but I simply think that there are two possibilities: some techniques didn't precise like we think, or some techniques are today able to detect new interactions (there's also a third possibility: experimental wrong, but only the reproduction of results can say us something more).