ZFOURGE/CANDELS: ON THE EVOLUTION OFM* GALAXY PROGENITORS FROMz= 3 TO 0.5

Abstract

Galaxies with stellar masses near M * contain the majority of stellar mass in the universe, and are therefore of special interest in the study of galaxy evolution. The Milky Way (MW) and Andromeda (M31) have present-day stellar masses near M * , at 5 × 10 10 M (defined here to be MW-mass) and 10 11 M (defined to be M31-mass). We study the typical progenitors of these galaxies using the FourStar Galaxy Evolution Survey (ZFOURGE). ZFOURGE is a deep medium-band near-IR imaging survey, which is sensitive to the progenitors of these galaxies out to z ∼ 3. We use abundance-matching techniques to identify the main progenitors of these galaxies at higher redshifts. We measure the evolution in the stellar mass, rest-frame colors, morphologies, far-IR luminosities, and star formation rates, combining our deep multiwavelength imaging with near-IR Hubble Space Telescope imaging from Cosmic Near-IR Deep Extragalactic Legacy Survey (CANDELS), and Spitzer and Herschel far-IR imaging from Great Observatories Origins Deep Survey-Herschel and CANDELS-Herschel. The typical MW-mass and M31-mass progenitors passed through the same evolution stages, evolving from blue, star-forming disk galaxies at the earliest stages to redder dust-obscured IR-luminous galaxies in intermediate stages and to red, more quiescent galaxies at their latest stages. The progenitors of the MW-mass galaxies reached each evolutionary stage at later times (lower redshifts) and with stellar masses that are a factor of two to three lower than the progenitors of the M31-mass galaxies. The process driving this evolution, including the suppression of star formation in present-day M * galaxies, requires an evolving stellar-mass/halo-mass ratio and/or evolving halo-mass threshold for quiescent galaxies. The effective size and SFRs imply that the baryonic cold-gas fractions drop as galaxies evolve from high redshift to z ∼ 0 and are strongly anticorrelated with an increase in the Sérsic index. Therefore, the growth of galaxy bulges in M * galaxies corresponds to a rapid decline in the galaxy gas fractions and/or a decrease in the star formation efficiency.

THE SFR–M* RELATION AND EMPIRICAL STAR FORMATION HISTORIES FROM ZFOURGE AT 0.5 < z < 4*

“…Papovich et al (2015) find similar results in their analysis of the progenitors of galaxies with present-day masses of the Milky Way and M31 galaxies. Finally, we have repeated this comparison using the SFR-M * parameterizations provided by Whitaker et al (2014) and Schreiber et al (2015) and in both cases we find similar disagreements.…”

KINEMATIC DOWNSIZING AT z ∼ 2

“…They have much lower "kinematic order" (V rot σ g ) and tend to fall to low V rot from the Tully-Fisher relation. For perspective, these results imply that a Milky-Way progenitor at z ∼ 2 (log M * /M ≈ 9.8; Papovich et al 2015) is likely still in the process of forming a disk. Combining both V rot and σ g in S 0.5 , all of the galaxies in SIGMA fall on the S 0.5 Tully-Fisher relation, indicating that many galaxies at low mass have strong contributions of kinematic support in the form of σ g .…”

Structural and Star-forming Relations since z ∼ 3: Connecting Compact Star-forming and Quiescent Galaxies

“….75, respectively (see e.g., Figure4 of Papovich et al 2015). Here we adopt mass growth by a factor of 20 to follow the growth of a population of SFGs that probe a significant fraction of the parameter space in the structural relations.…”

“…Since galaxies are believed to evolve in mass by much more than either of these numbers, i.e., by 20´over the same redshift range (van Dokkum et al 2010;Behroozi et al 2013;Moster et al 2013;Papovich et al 2015), the excursions and zero point changes are therefore both small compared to the overall mass trend. This suggests that M 1 SF  S -can be interpreted as an approximate evolutionary track and that galaxies evolve along it while still star forming (neglecting the small decline in zero point).…”