Rest-frame UV--Optically Selected Galaxies at 2.3<z<3.5: Searching for
  Dusty Star-forming and Passively-Evolving Galaxies
  A new set of color selection criteria (VJL) analogous with the BzK method is
designed to select both star-forming galaxies (SFGs) and passively-evolving
galaxies (PEGs) at 2.3<z<3.5 by using rest-frame UV--optical (V-J vs. J-L)
colors. The criteria are thoroughly tested with theoretical stellar population
synthesis models and real galaxies with spectroscopic redshifts to evaluate
their efficiency and contamination. We apply the well-tested VJL criteria to
the HST/WFC3 Early Release Science field and study the physical properties of
selected galaxies. The redshift distribution of selected SFGs peaks at z~2.7,
slightly lower than that of Lyman Break Galaxies at z~3. Comparing the observed
mid-infrared fluxes of selected galaxies with the prediction of pure stellar
emission, we find that our VJL method is effective at selecting massive dusty
SFGs that are missed by the Lyman Break Technique. About half of the star
formation in massive (M_{star}>10^{10}M_{Sun}) galaxies at 2.3<z<3.5 is
contributed by dusty (extinction E(B-V)>0.4) SFGs, which however, only account
for ~20% of the number density of massive SFGs. We also use the mid-infrared
fluxes to clean our PEG sample, and find that galaxy size can be used as a
secondary criterion to effectively eliminate the contamination of dusty SFGs.
The redshift distribution of the cleaned PEG sample peaks at z~2.5. We find 6
PEG candidates at z>3 and discuss possible methods to distinguish them from
dusty contamination. We conclude that at least part of our candidates are real
PEGs at z~3, implying that this type of galaxies began to form their stars at
z>5. We measure the integrated stellar mass density of PEGs at z~2.5 and set
constraints on it at z>3. We find that the integrated stellar mass density
grows by at least about factor of 10 in 1 Gyr at 3<z<5 and by another factor of
10 in next 3.5 Gyr (1<z<3).
