The Massive Ancient Galaxies at z > 3 NEar-infrared (MAGAZ3NE) Survey: Confirmation of Extremely Rapid Star Formation and Quenching Timescales for Massive Galaxies in the Early Universe
The Massive Ancient Galaxies at z > 3 NEar-infrared (MAGAZ3NE) Survey: Confirmation of Extremely Rapid Star Formation and Quenching Timescales for Massive Galaxies in the Early Universe
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DOI：
10.3847/1538-4357/abb819
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发表时间：
2020-09
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通讯作者：
Ben Forrest;Z. C. Marsan;M. Annunziatella;G. Wilson;A. Muzzin;D. Marchesini;M. Cooper;J. Chan;I. McConachie;P. Gomez;Erin Kado-Fong;F. L. Barbera;Daniel Lange-Vagle;J. Nantais;M. Nonino;P. Saracco;M. Stefanon;R. V. D. van der Burg
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作者：
Ben Forrest;Z. C. Marsan;M. Annunziatella;G. Wilson;A. Muzzin;D. Marchesini;M. Cooper;J. Chan;I. McConachie;P. Gomez;Erin Kado-Fong;F. L. Barbera;Daniel Lange-Vagle;J. Nantais;M. Nonino;P. Saracco;M. Stefanon;R. V. D. van der Burg
我们利用Keck/MOSFIRE对XMM-VIDEO和COSMOS-UtraVISTA视场中红移z>；3的16个恒星质量为>；11的星系进行了近红外光谱确认，这是大质量古星系z>；3近红外(MAGAZ3NE)测量的一部分。其中8个超大质量星系(UMG)的特定恒星形成率(SSFR)为1 Gyr−1。这些星系的恒星形成历史模型描述了这些星系的大部分恒星是在数百兆年持续时间的剧烈爆发中形成的，在此期间每年形成数百到数千个太阳质量。观测前<；1Gyr的形成年龄与由Dn(4000)和(Hδ)测量得到的年龄一致。在这些爆发的恒星形成阶段之后，快速猝灭通常发生在观测前不到350Myr，导致了一半样本的恒星爆发后SED和光谱。快速形成的时间尺度与ALMA观测到的尘埃星暴的极端恒星形成率是一致的，这表明这样的尘埃星系是这些UMG的祖先。虽然在以前的研究中已经提出了这样的形成历史，但这里介绍的大样本提供了迄今为止最令人信服的证据，证明在早期宇宙中，强健的恒星形成之后的快速猝灭几乎肯定是高质量星系的标准。这里展示的UMG被选为比Ks=21.7更亮，这增加了一个耐人寻味的可能性，即在这个时代甚至可能存在(更微弱的)更老的静止UMG。
We present near-infrared spectroscopic confirmations of a sample of 16 photometrically selected galaxies with stellar masses >11 at redshift z > 3 from the XMM-VIDEO and COSMOS-UltraVISTA fields using Keck/MOSFIRE as part of the Massive Ancient Galaxies At z > 3 NEar-infrared (MAGAZ3NE) survey. Eight of the ultramassive galaxies (UMGs) have specific star formation rates (sSFR) 1 Gyr−1. Model star formation histories of these galaxies describe systems that formed the majority of their stars in vigorous bursts of several hundred megayear duration around during which hundreds to thousands of solar masses were formed per year. These formation ages of <1 Gyr prior to observation are consistent with ages derived from measurements of Dn(4000) and (Hδ). Rapid quenching followed these bursty star-forming periods, generally occurring less than 350 Myr before observation, resulting in post-starburst SEDs and spectra for half the sample. The rapid formation timescales are consistent with the extreme star formation rates observed in dusty starbursts observed with ALMA, suggesting that such dusty galaxies are progenitors of these UMGs. While such formation histories have been suggested in previous studies, the large sample introduced here presents the most compelling evidence yet that vigorous star formation followed by rapid quenching is almost certainly the norm for high-mass galaxies in the early universe. The UMGs presented here were selected to be brighter than Ks = 21.7, raising the intriguing possibility that even (fainter) older quiescent UMGs could exist at this epoch.