Eric Bell (MPIA) and I spent some time talking about making precise measures of the merger rate. This was inspired by my finishing up the Masjedi et al paper on the growth of LRGs from accretion of satellites. The main uncertainty, of course, is the merging time-scale. We use a time-scale based on dynamical friction, but that is only good to factor-of-two at best. Will we ever have a reliable statistical measure of the growth of galaxies by merging? Perhaps if we have models that build realistic galaxies in a cosmological context.
Bell and I also discussed the project I was discussing a while back with Darren Croton (Berkeley): If galaxies at the massive, red end of the red sequence grow by merging, then the color-magnitude relation should flatten out there. That is, you can't maintain a linear relationship between color and luminosity if galaxies are merging prodigiously. This project requires good photometry at the bright end. Right now, Blanton and I are among the few on SDSS who can provide.
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