论文标题
$ z> 3 $近红外（Magaz3ne）的巨大古老星系调查：确认早期宇宙中巨大星系的恒星形成和淬火时间尺度
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
论文作者
论文摘要
我们介绍了16个具有恒星质量对数（m_star/m_sun）的16个光学选择星系样品的近红外光谱证实，> 11在XMM-VIDEO和COSMOS-OULTRAVISTA领域的RedShift Z> 3处使用KECK/MOSFIRE，使用Magaz3ne调查。八个超质量星系（UMGS）具有特定的恒星形成率（SSFR）<0.03 Gyr-1，其发射线可忽略不计。另外七个UMG显示出与活性银河核和/或恒星形成一致的发射线，而只有一个UMG的SSFR> 1 Gyr-1。这些星系的模型恒星形成历史描述了在4 <z <6d的剧烈爆发中形成大多数恒星的系统，每年形成数百至数千个太阳能。在观察之前，这些<1 Gyr的形成年龄与从DN（4000）和EW0（Hδ）的测量结果得出的年龄一致。快速淬火遵循这些爆发的恒星形成期，观察前通常小于350 MYR，导致一半样本的恒星后SED和光谱。快速的形成时间尺度与在Alma观察到的4 <Z <7尘土飞扬的星空爆炸中观察到的极端恒星形成速率一致，这表明这种尘土飞扬的星系是这些UMG的祖细胞。尽管在先前的研究中已经提出了这样的形成历史，但此处引入的大型样本提出了最令人信服的证据，表明剧烈的恒星形成后，快速淬火几乎可以肯定是早期宇宙中高质量星系的常态。选择此处介绍的UMG比KS = 21.7更明亮，这提出了令人着迷的可能性，即在这个时期内也可能存在（较淡淡的）较旧的静态UMG。
We present near-infrared spectroscopic confirmations of a sample of 16 photometrically-selected galaxies with stellar masses log(M_star/M_sun) > 11 at redshift z > 3 from the XMM-VIDEO and COSMOS-UltraVISTA fields using Keck/MOSFIRE as part of the MAGAZ3NE survey. Eight of the ultra-massive galaxies (UMGs) have specific star formation rates (sSFR) < 0.03 Gyr-1, with negligible emission lines. Another seven UMGs show emission lines consistent with active galactic nuclei and/or star formation, while only one UMG has 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 Myr duration around 4 < z < 6during 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 EW0(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 4 < z < 7 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.
