Using observations from the FourStar Galaxy Evolution Survey (ZFOURGE), we obtain the deepest measurements to date of the galaxy stellar mass function at 0.2 < z < 3. ZFOURGE provides wellconstrained photometric redshifts made possible through deep medium-bandwidth imaging at 1-2µm. We combine this with HST imaging from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS), allowing for the efficient selection of both blue and red galaxies down to stellar masses ∼ 10 9.5 M ⊙ at z ∼ 2.5. The total surveyed area is 316 arcmin 2 distributed over three independent fields. We supplement these data with the wider and shallower NEWFIRM Medium-Band Survey (NMBS) to provide stronger constraints at high masses. Several studies at z ≤ 1.5 have revealed a steepening of the slope at the low-mass end of the stellar mass function (SMF), leading to an upturn at masses < 10 10 M ⊙ that is not well-described by a standard single-Schechter function. We find evidence that this feature extends to at least z ∼ 2, and that it can be found in both the star-forming and quiescent populations individually. The characteristic mass (M * ) and slope at the lowest masses (α) of a double-Schechter function fit to the SMF stay roughly constant at Log(M/M ⊙ ) ∼ 10.65 and ∼ −1.5 respectively. The SMF of star-forming galaxies has evolved primarily in normalization, while the change in shape is relatively minor. Our data allow us for the first time to observe a rapid buildup at the low-mass end of the quiescent SMF. Since z = 2.5, the total stellar mass density of quiescent galaxies (down to 10 9 M ⊙ ) has increased by a factor of ∼12 whereas the mass density of star-forming galaxies only increases by a factor of ∼2.2. * This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

We study galactic star-formation activity as a function of environment and stellar mass over 0.5 9 (9.5) at z=1.3 (2.0). This method, when applied to a mock catalog with the photometric-redshift precision (σ z /(1 + z) 0.02) of ZFOURGE, recovers galaxies in low-and high-density environments accurately. We quantify the environmental quenching efficiency, and show that at z > 0.5 it depends on galaxy stellar mass, demonstrating that the effects of quenching related to (stellar) mass and environment are not separable. In high-density environments, the mass and environmental quenching efficiencies are comparable for massive galaxies (log(M/M ⊙ ) 10.5) at all redshifts. For lower mass galaxies (log(M/M ) ⊙ ) 10), the environmental quenching efficiency is very low at z 1.5, but increases rapidly with decreasing redshift. Environmental quenching can account for nearly all quiescent lower mass galaxies (log(M/M ⊙ ) ∼ 9-10), which appear primarily at z 1.0. The morphologies of lower mass quiescent galaxies are inconsistent with those expected of recently quenched star-forming galaxies. Some environmental process must transform the morphologies on similar timescales as the environmental quenching itself. The evolution of the environmental quenching favors models that combine gas starvation (as galaxies become satellites) with gas exhaustion through star-formation and outflows ("overconsumption"), and additional processes such as galaxy interactions, tidalCorresponding author: Lalitwadee Kawinwanichakij kawinwanichakij@physics.tamu.edu * This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile. 2 stripping, and disk fading to account for the morphological differences between the quiescent and star-forming galaxy populations.

We present the results from a new search for candidate galaxies at z ≈ 8.5–11 discovered over the 850 arcmin2 area probed by the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS). We use a photometric-redshift selection including both Hubble and Spitzer Space Telescope photometry to robustly identify galaxies in this epoch at H 160 < 26.6. We use a detailed vetting procedure, including screening against persistence and stellar contamination, and the inclusion of ground-based imaging and follow-up Hubble Space Telescope imaging to build a robust sample of 11 candidate galaxies, three presented here for the first time. The inclusion of Spitzer/IRAC photometry in the selection process reduces contamination, and yields more robust redshift estimates than Hubble alone. We constrain the evolution of the rest-frame ultraviolet luminosity function via a new method of calculating the observed number densities without choosing a prior magnitude bin size. We find that the abundance at our brightest probed luminosities (M UV = − 22.3) is consistent with predictions from simulations that assume that galaxies in this epoch have gas depletion times at least as short as those in nearby starburst galaxies. Due to large Poisson and cosmic variance uncertainties, we cannot conclusively rule out either a smooth evolution of the luminosity function continued from z = 4–8, or an accelerated decline at z > 8. We calculate that the presence of seven galaxies in a single field Extended Groth Strip is an outlier at the 2σ significance level, implying the discovery of a significant over-density. These scenarios will be imminently testable to high confidence within the first year of observations of the James Webb Space Telescope.