Abstract
We study the red sequence in a cluster of galaxies at z=1.62 and follow its
evolution over the intervening 9.5 Gyr to the present day. Using deep YJKs
imaging with the HAWK-I instrument on the VLT we identify a tight red sequence
and construct its rest-frame i-band luminosity function (LF). There is a marked
deficit of faint red galaxies in the cluster that causes a turnover in the LF.
We compare the red sequence LF to that for clusters at z<0.8 correcting the
luminosities for passive evolution. The shape of the cluster red sequence LF
does not evolve between z=1.62 and z=0.7 but at z<0.7 the faint population
builds up significantly. On the other hand, the inferred total light on the red
sequence grows by a factor of ~3 and the bright end of the LF becomes more
populated over the period from z=1.62 to 0.7. We construct a simple model for
red sequence evolution that grows the red sequence in total luminosity and
matches the constant LF shape at z>0.7. In this model the cluster accretes
quenched blue galaxies from the field and subsequently allows them to merge. An
average of three mergers between z=1.62 and z=0.7 match the observed luminosity
functions at the two redshifts. The inferred merger rate is consistent with
other studies of this cluster. Our result supports the picture that galaxy
merging during the major growth phase of massive clusters is an important
process in shaping the red sequence population at all luminosities.
Users
Please
log in to take part in the discussion (add own reviews or comments).