In a very special group meeting, Anja von der Linden (MPA) and Eric Bell (MPIA) gave back-to-back short talks on galaxy evolution. von der Linden is looking for evidence that brightest cluster galaxies have a different formation mechanism from field or ordinary galaxies of the same mass and color. Her control sample is so nicely composed, she can rule out the null hypothesis at good confidence, despite the fact that her primary result is that in fact the BCGs are amazingly similar to galaxies of the same mass and color in other environments.
Bell asks whether the evolution in the total mass density in red an blue galaxies can be explained with passive models, or whether merging is necessary and sufficient. He finds both, ie, that merging is both necessary and sufficient to explain the evolution of the red sequence, with the caveat that everything has large error bars.
In the afternoon, Lam Hui (Columbia) showed us various issues with doing precision (and accurate) cosmology with the next generation of huge surveys, including baryon acoustic feature, which is close to our hearts here at NYU. He gave us some great stuff to look for with PRIMUS.