Ryan F. Quadri

3D-HST: a wide-field grism spectroscopic survey with the Hubble Space Telescope

We present 3D-HST, a near-infrared spectroscopic Treasury program with the Hubble Space Telescope for studying nthe physical processes that shape galaxies in the distant universe. 3D-HST provides rest-frame optical spectra for na sample of ∼7000 galaxies at 1 < z < 3.5, the epoch when ∼60% of all star formation took place, the number ndensity of quasars peaked, the first galaxies stopped forming stars, and the structural regularity that we see in ngalaxies today must have emerged. 3D-HST will cover three quarters (625 arcmin^2) of the CANDELS Treasury nsurvey area with two orbits of primary WFC3/G141 grism coverage and two to four orbits with the ACS/G800L ngrism in parallel. In the IR, these exposure times yield a continuum signal-to-noise ratio of ∼5 per resolution element nat H_140 ∼ 23.1 and a 5σ emission-line sensitivity of ∼5 × 10^(−17) erg s^−1 cm^(−2) for typical objects, improving by na factor of ∼2 for compact sources in images with low sky background levels. The WFC3/G141 spectra provide ncontinuous wavelength coverage from 1.1 to 1.6μm at a spatial resolution of ∼0.13, which, combined with their ndepth, makes them a unique resource for studying galaxy evolution. We present an overview of the preliminary nreduction and analysis of the grism observations, including emission-line and redshift measurements from combined nfits to the extracted grism spectra and photometry from ancillary multi-wavelength catalogs. The present analysis nyields redshift estimates with a precision of σ(z) = 0.0034(1 + z), or σ(v) ≈ 1000 km s^(−1). We illustrate how nthe generalized nature of the survey yields near-infrared spectra of remarkable quality for many different types nof objects, including a quasar at z = 4.7, quiescent galaxies at z ∼ 2, and the most distant T-type brown dwarf nstar known. The combination of the CANDELS and 3D-HST surveys will provide the definitive imaging and nspectroscopic data set for studies of the 1 < z < 3.5 universe until the launch of the James Webb Space Telescope.

The number density and mass density of star-forming and quiescent galaxies at 0.4 ≤ z ≤ 2.2

We study the buildup of the bimodal galaxy population using the NEWFIRM Medium-Band Survey, which provides excellent redshifts and well-sampled spectral energy distributions of {approx}27, 000 galaxies with K 3 x 10{sup 10} M{sub sun} increases by a factor of {approx}10 from z {approx} 2 to the present day, whereas the mass density in star-forming galaxies is flat or decreases over the same time period. Modest mass growth by a factor of {approx}2 of individual quiescent galaxies can explain roughly half of the strong density evolution at masses >10{sup 11} M{sub sun}, due to the steepness of the exponential tail of the mass function. The rest of the density evolution of massive, quiescent galaxies is likely due to transformation (e.g., quenching) of the massive star-forming population, a conclusion which ismorexa0» consistent with the density evolution we observe for the star-forming galaxies themselves, which is flat or decreasing with cosmic time. Modest mass growth does not explain the evolution of less massive quiescent galaxies ({approx}10{sup 10.5} M{sub sun}), which show a similarly steep increase in their number densities. The less massive quiescent galaxies are therefore continuously formed by transforming galaxies from the star-forming population.«xa0less

Galaxy stellar mass functions from ZFOURGE/CANDELS: an excess of low-mass galaxies since z=2 and the rapid buildup of quiescent galaxies

Using observations from the FourStar Galaxy Evolution Survey (ZFOURGE), we obtain the deepest measurements to date of the galaxy stellar mass function (SMF) at 0.2 < z < 3. ZFOURGE provides well-constrained photometric redshifts made possible through deep medium-bandwidth imaging at 1-2 μm. We combine this with Hubble Space Telescope imaging from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey, allowing for the efficient selection of both blue and red galaxies down to stellar masses of ~109.5 M ☉ at z ~ 2.5. The total surveyed area is 316 arcmin2 distributed over three independent fields. We supplement these data with the wider and shallower NEWFIRM Medium-Band Survey 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 SMF, leading to an upturn at masses <1010 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 109 M ☉) has increased by a factor of ~12, whereas the mass density of star-forming galaxies only increases by a factor of ~2.2.

Galaxy clustering in the NEWFIRM Medium Band Survey: the relationship between stellar mass and dark matter halo mass at 1 <z< 2

We present an analysis of the clustering of galaxies as a function of their stellar mass at 1 1 there may be a discrepancy between the space density and clustering predicted by the halo model and the measured clustering and space density. This could imply that there is a problem with one or more ingredient of the halo model at these redshifts, for instance, the halo bias relation may not yet be precisely calibrated at high halo masses or galaxies may not be distributed within halos following a Navarro-Frenk-White profile.

STELLAR KINEMATICS OF z ∼ 2 GALAXIES AND THE INSIDE-OUT GROWTH OF QUIESCENT GALAXIES* , **

Using stellar kinematics measurements, we investigate the growth of massive, quiescent galaxies from z ~{} 2 to today. We present X-Shooter spectra from the UV to NIR and dynamical mass measurements of five quiescent massive ({gt}10

The SFR-M* Relation and Empirical Star-Formation Histories from ZFOURGE at 0.5 < z < 4

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First results from the 3D-HST survey: The striking diversity of massive galaxies at z > 1

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A Substantial Population of Massive Quiescent Galaxies at z ~ 4 from ZFOURGE

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FIRST RESULTS FROM Z -FOURGE : DISCOVERY OF A CANDIDATE CLUSTER AT z = 2.2 IN COSMOS

) galaxies at z ~{} 2. This triples the sample of z {gt} 1.5 galaxies with well-constrained ({

HerMES: The Contribution to the Cosmic Infrared Background from Galaxies Selected by Mass and Redshift

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