Galaxy stellar mass functions from zfourge/candels: An excess of low-mass galaxies since z = 2 and the rapid buildup of quiescent galaxies

Adam R. Tomczak, Ryan F. Quadri, Kim Vy H. Tran, Ivo Labbé, Caroline M.S. Straatman, Casey Papovich, Karl Glazebrook, Rebecca Allen, Gabriel B. Brammer, Glenn G. Kacprzak, Lalitwadee Kawinwanichakij, Daniel D. Kelson, Patrick J. McCarthy, Nicola Mehrtens, Andrew J. Monson, S. Eric Persson, Lee R. Spitler, Vithal Tilvi, Pieter Van Dokkum

Research output: Contribution to journalArticlepeer-review

355 Scopus citations


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.

Original languageEnglish (US)
Article number85
JournalAstrophysical Journal
Issue number2
StatePublished - Mar 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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