14
Luminosity Functions
•Features to note
–Morphology matters, also field vs. cluster.
–M* in rich clusters isn’t a bad “standard candle”
–cD galaxies in cluster centers are special cases; they are like massive ellipticals but have extra stellar envelopes.  They do not fit extrapolations of ellipitical LFs.  More on this in Chapter 4.
–Low luminosity end of LFs not well determined (Irr and dwarf ellipticals).  Again SDSS will probably be the best word on this (if it goes faint enough).