Fernando Buitrago, Ignacio Trujillo, Christopher J. Conselice, Boris Haeussler
Present-day massive galaxies are composed mostly of early-type objects. It is
unknown whether this was also the case at higher redshifts. In a hierarchical
assembling scenario the morphological content of the massive population is
expected to change with time from disk-like objects in the early Universe to
spheroid-like galaxies at present. In this paper we have probed this
theoretical expectation by compiling a large sample of massive
(M_{stellar}>10^{11} h_{70}^{-2} M_{Sun}$) galaxies in the redshift interval 0
< z < 3. Our sample of 1082 objects comprises 207 local galaxies selected from
SDSS plus 875 objects observed with the HST belonging to the POWIR/DEEP2 and
GNS surveys. 639 of our objects have spectroscopic redshifts. Our morphological
classification is done in the V-band restframe both quantitatively (using the
Sersic index as a morphological proxy) and qualitative (by visual inspection).
Using both techniques we find an enormous change on the dominant morphological
class with cosmic time. The fraction of early-type galaxies among the massive
galaxy population has changed from ~20-30% at z~3 to ~70% at z=0. Elliptical
galaxies have been the predominant morphological class for massive galaxies
since only z~1.
View original:
http://arxiv.org/abs/1111.6993
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