DESI Survey Validation Spectra Reveal an Increasing Fraction of Recently Quenched Galaxies at z ∼ 1

Journal Article · 25 April 2023 · The Astrophysical Journal. Letters

DOI: https://doi.org/10.3847/2041-8213/acc9b5 · OSTI ID:1971709

Setton, David J. ; Dey, Biprateep ; Khullar, Gourav ; Bezanson, Rachel ; Newman, Jeffrey A. ; Aguilar, Jessica N. ; Ahlen, Steven ; Andrews, Brett H. ; Brooks, David ; de la Macorra, Axel; Dey, Arjun ; Eftekharzadeh, Sarah ; Font-Ribera, Andreu ; A Gontcho, Satya Gontcho ; Kremin, Anthony ; Juneau, Stephanie ; Landriau, Martin ; Meisner, Aaron ; Miquel, Ramon ; Moustakas, John ; Pearl, Alan ; Prada, Francisco ; Tarlé, Gregory ; Siudek, Małgorzata ; Weaver, Benjamin Alan; Zhou, Zhimin ; Zou, Hu

Abstract We utilize ∼17,000 bright luminous red galaxies (LRGs) from the novel Dark Energy Spectroscopic Instrument Survey Validation spectroscopic sample, leveraging its deep (∼2.5 hr galaxy ⁻¹ exposure time) spectra to characterize the contribution of recently quenched galaxies to the massive galaxy population at 0.4 < z < 1.3. We use Prospector to infer nonparametric star formation histories and identify a significant population of recently quenched galaxies that have joined the quiescent population within the past ∼1 Gyr. The highest-redshift subset (277 at z > 1) of our sample of recently quenched galaxies represents the largest spectroscopic sample of post-starburst galaxies at that epoch. At 0.4 < z < 0.8, we measure the number density of quiescent LRGs, finding that recently quenched galaxies constitute a growing fraction of the massive galaxy population with increasing look-back time. Finally, we quantify the importance of this population among massive ( $\log \left(M_{\star }/M_{\odot }\right)$ > 11.2) LRGs by measuring the fraction of stellar mass each galaxy formed in the gigayear before observation, f _{1 Gyr} . Although galaxies with f _{1 Gyr} > 0.1 are rare at z ∼ 0.4 (≲0.5% of the population), by z ∼ 0.8, they constitute ∼3% of massive galaxies. Relaxing this threshold, we find that galaxies with f _{1 Gyr} > 5% constitute ∼10% of the massive galaxy population at z ∼ 0.8. We also identify a small but significant sample of galaxies at z = 1.1–1.3 that formed with f _{1 Gyr} > 50%, implying that they may be analogs to high-redshift quiescent galaxies that formed on similar timescales. Future analysis of this unprecedented sample promises to illuminate the physical mechanisms that drive the quenching of massive galaxies after cosmic noon.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: National Science Foundation (NSF); Polish National Agency for Academic Exchange (NAWA); USDOE; USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1971709
• Journal Information: The Astrophysical Journal. Letters, Journal Name: The Astrophysical Journal. Letters Journal Issue: 2 Vol. 947; ISSN 2041-8205
• Publisher: American Astronomical SocietyCopyright Statement
• Country of Publication: United States
• Language: English