论文标题
Z〜2.2处的昏迷祖细胞的光谱证实
Spectroscopic Confirmation of a Coma Cluster Progenitor at z ~ 2.2
论文作者
论文摘要
我们报告了$ z $ $ \ sim $ 2.2，Cosmos群集2.2（CC2.2）的宇宙领域中新的原始群集的光谱确认，最初被确定为窄带选择的H $α$发射候选者的过度密度。 With only two masks of Keck/MOSFIRE near-IR spectroscopy in both $H$ ($\sim$ 1.47-1.81 $μ$m) and $K$ ($\sim$ 1.92-2.40 $μ$m) bands ($\sim$ 1.5 hour each), we confirm 35 unique protocluster members with at least two emission lines detected with S/N $>$ 3. Combined with 12 extra members from the ZCOSMOS-DEEP光谱调查（总共47个），我们估计$ z_ {mean} $ = 2.23224 $ = 2.23224 $ \ pm $ 0.00101和$σ_{los} $ = 645 $ = 645 $ \ pm $ 69 km $ 69 km的$^$^$ 1} $ 1} $ 1} $ 1}的;假设该系统的病毒化和球形对称性，我们估计总质量为$ m_ {vir} $ $ \ sim $ $（1-2）\ times $ 10 $^{14} $ $ $ m _ {\ odot} $。我们评估了该系统的$δ_{g} $ \ sim $ 7的数字密度增强，我们认为该结构可能不会以$ z $ \ sim $ 2.2的$ z $ \ sim $ 2.2进行全面病毒。但是，在球形崩溃模型中，预计$δ_{g} $将增长到线性物质增强$ \ sim $ 1.9 $ 1.9乘$ z $ = 0，超过了1.69的倒塌阈值，并导致完全折叠和病毒化的coma-type结构，总质量为$ m_ $ m_ $ _ {$ z $} $ {$} $ {$} $ = 0） 9.2 $ \ times $ 10 $^{14} $ $ m _ {\ odot} $。该观察性有效的确认表明，当与辅助光度数据结合使用时，可以使用大型窄带发射线星系调查在大多数由星形星系统治的时候有效地追踪大规模结构和原粉状。
We report the spectroscopic confirmation of a new protocluster in the COSMOS field at $z$ $\sim$ 2.2, COSMOS Cluster 2.2 (CC2.2), originally identified as an overdensity of narrowband selected H$α$ emitting candidates. With only two masks of Keck/MOSFIRE near-IR spectroscopy in both $H$ ($\sim$ 1.47-1.81 $μ$m) and $K$ ($\sim$ 1.92-2.40 $μ$m) bands ($\sim$ 1.5 hour each), we confirm 35 unique protocluster members with at least two emission lines detected with S/N $>$ 3. Combined with 12 extra members from the zCOSMOS-deep spectroscopic survey (47 in total), we estimate a mean redshift and a line-of-sight velocity dispersion of $z_{mean}$=2.23224 $\pm$ 0.00101 and $σ_{los}$=645 $\pm$ 69 km s$^{-1}$ for this protocluster, respectively. Assuming virialization and spherical symmetry for the system, we estimate a total mass of $M_{vir}$ $\sim$ $(1-2) \times$10$^{14}$ $M_{\odot}$ for the structure. We evaluate a number density enhancement of $δ_{g}$ $\sim$ 7 for this system and we argue that the structure is likely not fully virialized at $z$ $\sim$ 2.2. However, in a spherical collapse model, $δ_{g}$ is expected to grow to a linear matter enhancement of $\sim$ 1.9 by $z$=0, exceeding the collapse threshold of 1.69, and leading to a fully collapsed and virialized Coma-type structure with a total mass of $M_{dyn}$($z$=0) $\sim$ 9.2$\times$10$^{14}$ $M_{\odot}$ by now. This observationally efficient confirmation suggests that large narrowband emission-line galaxy surveys, when combined with ancillary photometric data, can be used to effectively trace the large-scale structure and protoclusters at a time when they are mostly dominated by star-forming galaxies.
