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

作者：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; Gontcho, Satya Gontcho; Kremin, Anthony; Juneau, Stephanie; Landriau, Martin; Meisner, Aaron; Miquel, Ramon; Moustakas, John; Pearl, Alan; Prada, Francisco; Tarle, Gregory; Siudek, Malgorzata; Weaver, Benjamin Alan; Zhou, Zhimin; Zou, Hu

来源：Astrophysical Journal Letters, 2023, 947(2): L31.

DOI：10.3847/2041-8213/acc9b5

• STAR-FORMATION HISTORIES
• POST-STARBURST GALAXIES
• OSCILLATION SPECTROSCOPIC SURVEY
• MASSIVE POSTSTARBURST GALAXIES
• ACTIVE GALACTIC NUCLEI
• QUIESCENT GALAXIES
• STELLAR POPULATION
• MOLECULAR GAS
• INTERMEDIATE-REDSHIFT
• PHYSICAL-PROPERTIES

We utilize similar to 17,000 bright luminous red galaxies (LRGs) from the novel Dark Energy Spectroscopic Instrument Survey Validation spectroscopic sample, leveraging its deep (similar to 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 similar to 1 Gyr. The highest-redshift subset (277 at z > 1) of our sample of recently quenched galaxies represents the largest spectroscopic sample of poststarburst 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(M-star/M-circle dot) > 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 similar to 0.4 (less than or similar to 0.5% of the population), by similar to 0.8, they constitute similar to 3% of massive galaxies. Relaxing this threshold, we find that galaxies with f(1 Gyr) > 5% constitute similar to 10% of the massive galaxy population at z similar to 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.

• 单位
  中国科学院; 中国科学院国家天文台