halo occupation, morphology–density, gaps

Masjedi showed me his result that he cannot fit the LRG–LRG correlation function at small scales with a halo occupation model that uses the NFW profile for the galaxies. This is true even if he allows the concentrations of the halos to vary. This is a nice result and will motivate him to fit for the Masjedi profile. Look out Moore and NFW!

Quintero made this plot (below), which shows that although there is a relationship between Sérsic index (concentration) and clustocentric distance (environment) when we look at all SDSS galaxies (leftmost panels, top is color histogram, bottom is dependence of quantiles of concentration on environment), if we take narrow color slices, there is no concentration–environment relation within any slice. This is not true if we reverse things; ie, if we take narrow concentration slices, there is a color–environment relation even within each slice. This reflects on the relative fundamental-ness of the color–environment and concentration–environment relations. By the way, the latter is often called, in recent literature, the morphology–density relation.

I continued to work on coding the magnitude gaps.