论文标题
z $ \ sim $ 3时典型的巨大静态星系是季后赛
The Typical Massive Quiescent Galaxy at z$\sim$3 is a Post-starburst
论文作者
论文摘要
我们在2.4 <z <3.3的第一个静态星系中获得了第一个较大的九个静态星系样本的哈勃空间望远镜WFC3/G141的光谱确认。它们的平均近紫外/光学休息框架频谱的特征是衰减较低（AV $ \ sim $ 0.6 mag）和强大的Balmer休息时间，大于4000个休息时间，对应于相当小的$ \ sim 300 $ 300 MYR。这正式将大部分经典选择的静态星系分为Z $ \ sim $ 3作为季后赛后，标志着它们与淬火时期的收敛。相对于Z $ \ SIM $ 1.5静态星系的快速光谱演化与剩余恒星形成的增加不匹配，这是根据[O II] 3727A发射的弱检测来判断的，这表明先前从z $ \ sim \ sim \ sim $ 0到1.8的急剧增加了气体的急剧增加。但是，无线电3GHz堆叠的发射意味着相对于z $ \ sim $ 1.5，无线电模式AGN活性的尘埃刺激性更强，或者是实质性的进化。
We have obtained spectroscopic confirmation with Hubble Space Telescope WFC3/G141 of a first sizeable sample of nine quiescent galaxies at 2.4<z<3.3. Their average near-UV/optical rest-frame spectrum is characterized by low attenuation (Av$\sim$0.6 mag) and a strong Balmer break, larger than the 4000 A break, corresponding to a fairly young age of $\sim$300 Myr. This formally classifies a substantial fraction of classically selected quiescent galaxies at z $\sim$ 3 as post-starbursts, marking their convergence to the quenching epoch. The rapid spectral evolution with respect to z $\sim$ 1.5 quiescent galaxies is not matched by an increase of residual star-formation, as judged from the weak detection of [O II]3727A emission, pointing to a flattening of the steep increase in gas fractions previously seen from z $\sim$ 0 to 1.8. However, radio 3GHz stacked emission implies either much stronger dust-obscured star formation or substantial further evolution in radio-mode AGN activity with respect to z $\sim$ 1.5.
