Prochaska, J. Xavier ; Neeleman, Marcel ; Kanekar, Nissim ; Rafelski, Marc (2019) ALMA C ii 158 μm Imaging of an H i-selected Major Merger at z ∼ 4 The Astrophysical Journal, 886 (2). L35. ISSN 2041-8213
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Official URL: http://doi.org/10.3847/2041-8213/ab55eb
Related URL: http://dx.doi.org/10.3847/2041-8213/ab55eb
Abstract
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.
Item Type: | Article |
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Source: | Copyright of this article belongs to IOP Publishing. |
Keywords: | Galaxy Mergers; Quasar Absorption Line Spectroscopy; Damped Lyman-Alpha Systems. |
ID Code: | 118047 |
Deposited On: | 12 May 2021 06:18 |
Last Modified: | 12 May 2021 06:18 |
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