Constraints on Quenching of Z ≲ 2 Massive Galaxies from the Evolution of the Average Sizes of Star-forming and Quenched Populations in COSMOS

Journal Article · Thu Apr 20 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA697A· OSTI ID:22872791

Faisst, A. L.; Carollo, C. M.; Tacchella, S. ^[1]; Capak, P. L. ^[2]; Renzini, A. ^[3]; Ilbert, O. ^[4]; McCracken, H. J. ^[5]

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1. Institute for Astronomy, Swiss Federal Institute of Technology, 8093 Zürich (Switzerland)
2. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
3. NAF—Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy)
4. Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France)
5. Institut d’Astrophysique de Paris, CNRS and UPMC, UMR 7095, 98 bis Boulevard Arago, F-75014, Paris (France)

We use >9400 log(m/M{sub ⊙})>10 quiescent and star-forming galaxies at z ≲ 2 in COSMOS/UltraVISTA to study the average size evolution of these systems, with focus on the rare ultra-massive population at log(m/M{sub ⊙})>11.4. The large 2 square degree survey area delivers a sample of ∼400 such ultra-massive systems. Accurate sizes are derived using a calibration based on high-resolution images from the Hubble Space Telescope. We find that at these very high masses, the size evolution of star-forming and quiescent galaxies is almost indistinguishable in terms of normalization and power-law slope. We use this result to investigate possible pathways of quenching massive m > M* galaxies at z < 2. We consistently model the size evolution of quiescent galaxies from the star-forming population by assuming different simple models for the suppression of star formation. These models include an instantaneous and delayed quenching without altering the structure of galaxies and a central starburst followed by compaction. We find that instantaneous quenching reproduces the observed mass-size relation of massive galaxies at z > 1 well. Our starburst+compaction model followed by individual growth of the galaxies by minor mergers is preferred over other models without structural change for log(m/M{sub ⊙})>11.0 galaxies at z > 0.5. None of our models is able to meet the observations at m > M* and z < 1 without significant contribution of post-quenching growth of individual galaxies via mergers. We conclude that quenching is a fast process in galaxies with m ≥ 10{sup 11} M {sub ⊙}, and that major mergers likely play a major role in the final steps of their evolution.

• OSTI ID: 22872791
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 839; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CALIBRATION
GALAXIES
INHIBITION
MASS
SPACE
STAR EVOLUTION
STARS
UNIVERSE