In group meeting, Berlind talked about reactions to NYU work at the SDSS meeting last week. This led to a discussion of Quintero's current project of looking for signs of the direction to the cluster in galaxies in the infall regions, the results of which were very well received at the meeting, apparently. We figured out that because Quintero is looking at broadband light, he won't be extremely sensitive to some of the effects claimed in the literature.
Berlind mentioned that Park (Seoul) is working on some environmental relations similar to those measured by Blanton and me. But he is using some kind of Nth-nearest neighbor statistic that has variable length scale (and a large median length-scale, and we have shown that only very small scales—Mpc or so—matter).
After group meeting, Berlind gave a short talk in the brown-bag about confirming some non-trivial relationships between cluster ages, masses, and clustering (as measured by the autocorrelation function). Age is positively correlated with clustering amplitude at masses below the nonlinear scale, but negatively above! Wechsler (Chicago) predicted this from simulations and Berlind has confirmed.
Sheldon, Masjedi, and I talked about ratios of cluster-mass and cluster-galaxy or galaxy-mass and galaxy-galaxy cross-correlations to measure the mass-to-light ratio as a function of scale. The observed power-law galaxy autocorrelation functions can only be explained in conventional CDM cosmology if these cross-correlation ratios have very specific shapes with radius. I hope this discussion was the birth of a new (and fast) project on this.
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