The Evolution of the Scatter of the Cosmic Average Color-Magnitude Relation: Demonstrating Consistency with the Ongoing Formation of Elliptical Galaxies

We present first measurements of the evolution of the scatter of the cosmic average early-type galaxy color-magnitude relation (CMR) from z = 1 to the present day, finding that it is consistent with models in which galaxies are constantly being added to the red sequence through truncation of star formation in blue cloud galaxies. We used a sample of over 700 red sequence, structurally selected early-type galaxies (defined to have Sersic index >2.5) with redshifts 0 < z < 1 taken from the Extended Chandra Deep Field South (173 galaxies) and the Sloan Digital Sky Survey (550 galaxies), constructing rest-frame U - V colors accurate to