MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. II. Star Formation Histories and Galaxy Quenching

By S. Belli, A. Newman, Richard S. Ellis. Astrophysical Journal, 2018

152 citations recorded by the source corpus.

We investigate the stellar populations for a sample of 24 quiescent galaxies at 1.5 < z < 2.5 using deep rest-frame optical spectra obtained with Keck MOSFIRE. By fitting templates simultaneously to the spectroscopic and photometric data and exploring a variety of star formation histories, we obtain robust measurements of median stellar ages and residual levels of star formation. After subtracting the stellar templates, the stacked spectrum reveals the Hα and [N ii] emission lines, providing an upper limit on the ongoing star formation rate of 0.9 ± 0.1 M ⊙ yr−1. By combining the MOSFIRE data with our sample of Keck LRIS spectra at lower redshift, we analyze the quiescent population at 1 < z < 2.5 in a consistent manner. We find a tight relation (with a scatter of 0.13 dex) between the stellar age and the rest-frame U − V and V − J colors, which can be used to estimate the age of quiescent galaxies, given their colors. Applying this age–color relation to large photometric samples, we are able to model the number density evolution for quiescent galaxies of various ages. We find evidence for two distinct quenching paths: a fast quenching that produces compact post-starburst systems and a slow quenching of larger galaxies. Fast quenching accounts for about a fifth of the growth of the red sequence at z ∼ 1.4 and half at z ∼ 2.2. We conclude that fast quenching is triggered by dramatic events, such as gas-rich mergers, while slow quenching is likely caused by a different physical mechanism.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6e9624b9c8638609fd01c8285aca19d11e9dd604

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In Astronomy and Astrophysics

1. Michele Moresco
2. A. Cimatti
3. L. Verde
4. L. Pozzetti
5. Raul Jimenez
6. A. Renzini
7. C. Conroy
8. E. Daddi

In Instrumentation

1. A. Cimatti
2. Michele Moresco
3. L. Pozzetti
4. L. Verde
5. Raul Jimenez
6. A. Renzini
7. E. Daddi
8. A. Gómez-Valent

Citations in the corpus

• Setting the Stage for Cosmic Chronometers. II. Impact of Stellar Population Synthesis Models Systematics and Full Covariance Matrix (2020, background): “…early stages of their life, they are mostly passively evolving (Cimatti et al. 2004; Treu et al. 2005; Pozzetti et al. 2010; Thomas et al. 2010; Choi et al. 2014; Onodera et al. 2015; Citro et al. 2016; Pacifici et al. 2016; Belli et al. 2019; Carnall et al. 2019; Estrada-Carpenter et al. 2019).”