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Fast, Slow, Early, Late: Quenching Massive Galaxies at z ∼ 0.8

Tacchella, Sandro; Conroy, Charlie; Faber, S.M.; Johnson, Benjamin D.; Leja, Joel; Barro, Guillermo; Cunningham, Emily C.; Deason, Alis J.; Guhathakurta, Puragra; Guo, Yicheng; Hernquist, Lars; Koo, David C.; McKinnon, Kevin; Rockosi, Constance M.; Speagle, Joshua S.; van Dokkum, Pieter; Yesuf, Hassen M.

Fast, Slow, Early, Late: Quenching Massive Galaxies at z ∼ 0.8 Thumbnail


Authors

Sandro Tacchella

Charlie Conroy

S.M. Faber

Benjamin D. Johnson

Joel Leja

Guillermo Barro

Emily C. Cunningham

Puragra Guhathakurta

Yicheng Guo

Lars Hernquist

David C. Koo

Kevin McKinnon

Constance M. Rockosi

Joshua S. Speagle

Pieter van Dokkum

Hassen M. Yesuf



Abstract

We investigate the stellar populations for a sample of 161 massive, mainly quiescent galaxies at 〈zobs〉 = 0.8 with deep Keck/DEIMOS rest-frame optical spectroscopy (HALO7D survey). With the fully Bayesian framework Prospector, we simultaneously fit the spectroscopic and photometric data with an advanced physical model (including nonparametric star formation histories, emission lines, variable dust attenuation law, and dust and active galactic nucleus emission), together with an uncertainty and outlier model. We show that both spectroscopy and photometry are needed to break the dust–age–metallicity degeneracy. We find a large diversity of star formation histories: although the most massive (M⋆ > 2 × 1011 M⊙) galaxies formed the earliest (formation redshift of zf ≈ 5–10 with a short star formation timescale of τSF ≲ 1 Gyr), lower-mass galaxies have a wide range of formation redshifts, leading to only a weak trend of zf with M⋆. Interestingly, several low-mass galaxies have formation redshifts of zf ≈ 5–8. Star-forming galaxies evolve about the star-forming main sequence, crossing the ridgeline several times in their past. Quiescent galaxies show a wide range and continuous distribution of quenching timescales (τquench ≈ 0–5 Gyr) with a median of $\langle {\tau }_{\mathrm{quench}}\rangle ={1.0}_{-0.9}^{+0.8}\,\mathrm{Gyr}$ and of quenching epochs of zquench ≈ 0.8–5.0 ($\langle {z}_{\mathrm{quench}}\rangle ={1.3}_{-0.4}^{+0.7}$). This large diversity of quenching timescales and epochs points toward a combination of internal and external quenching mechanisms. In our sample, rejuvenation and "late bloomers" are uncommon. In summary, our analysis supports the "grow-and-quench" framework and is consistent with a wide and continuously populated diversity of quenching timescales.

Citation

Tacchella, S., Conroy, C., Faber, S., Johnson, B. D., Leja, J., Barro, G., …Yesuf, H. M. (2022). Fast, Slow, Early, Late: Quenching Massive Galaxies at z ∼ 0.8. Astrophysical Journal, 926(2), Article 134. https://doi.org/10.3847/1538-4357/ac449b

Journal Article Type Article
Acceptance Date Dec 17, 2021
Online Publication Date Feb 18, 2022
Publication Date Feb 20, 2022
Deposit Date Jun 14, 2022
Publicly Available Date Jun 14, 2022
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 926
Issue 2
Article Number 134
DOI https://doi.org/10.3847/1538-4357/ac449b

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.





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