论文标题
Alma [CII] 158UM在Z〜4时进行高选择的主要合并成像
ALMA [CII] 158um imaging of an HI-Selected Major Merger at z~4
论文作者
论文摘要
我们提出了高空间分辨率（〜2KPC）Atacama大毫米/亚毫米/亚毫米阵列（ALMA）[CII] 158UM和dust-Continuum从Z = 3.7978中从Z = 3.7978中排放出来的粉尘 - continuum，其强烈的HI吸收（A damped lya Apsorber，dla，dla，dla，dla）在背景方面。我们的ALMA图像揭示了一对由〜6KPC（预计）进行主要合并的星系星系。在这些星系之间是第三个发射成分，相对于灰尘连续体高度升高（2x）[CII] 158UM发射，这可能是由与合并相关的剥离气体引起的。这两个原本正常星系的合并不伴有增强的恒星形成，与在大多数光度隔离的样品中检测到的合并相反。与合并相关的DLA表现出极端的运动学，对于DV90〜470km/s的低离子化金属线的速度宽度涵盖了[CII] 158UM发射中的速度扩散。我们建议，具有高DV90值的DLA是高红移正常星系中主要合并的路标，并使用高Z DLA中金属线的速度宽度的分布分布，以粗略地估计Z> 3个星系的比例，这些星系正在进行主要合并。
We present high spatial-resolution (~2kpc) Atacama Large Millimeter/submillimeter Array (ALMA) observations of [CII] 158um and dust-continuum emission from a galaxy at z=3.7978 selected by its strong HI absorption (a damped Lya absorber, DLA) against a background QSO. Our ALMA images reveal a pair of star-forming galaxies separated by ~6kpc (projected) undergoing a major merger. Between these galaxies is a third emission component with highly elevated (2x) [CII] 158um emission relative to the dust continuum, which is likely to arise from stripped gas associated with the merger. This merger of two otherwise-normal galaxies is not accompanied by enhanced star-formation, contrary to mergers detected in most luminosity-selected samples. The DLA associated with the merger exhibits extreme kinematics, with a velocity width for the low-ionization metal lines of Dv90~470km/s that spans the velocity spread revealed in the [CII] 158um emission. We propose that DLAs with high Dv90 values are a signpost of major mergers in normal galaxies at high redshifts, and use the distribution of the velocity widths of metal lines in high-z DLAs to provide a rough estimate the fraction of z>3 galaxies that are undergoing a major merger.
