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Title: The Extended [C ii] under Construction? Observation of the Brightest High-z Lensed Star-forming Galaxy at z = 6.2

We present results of [Cii] 158μm emission line observations, and report the spectroscopic redshift confirmation of a strongly lensed (μ∼ 20) star-forming galaxy, MACS0308-zD1 atz= 6.2078 ± 0.0002. The [Cii] emission line is detected with a signal-to-noise ratio >6 within the rest-frame UV-bright clump of the lensed galaxy (zD1.1) and exhibits multiple velocity components; the narrow [Cii] has a velocity full width half maximum (FWHM) of 110 ± 20 km s−1, while broader [Cii] is seen with an FWHM of 230 ± 50 km s−1. The broader [Cii] component is blueshifted (−80 ± 20 km s−1) with respect to the narrow [Cii] component, and has a morphology that extends beyond the UV-bright clump. We find that, while the narrow [Cii] emission is most likely associated with zD1.1, the broader component is possibly associated with a physically distinct gas component from zD1.1 (e.g., outflowing or inflowing gas). Based on the nondetection ofλ158μmdust continuum, we find that MACS0308-zD1's star formation activity occurs in a dust-free environment indicated by a strong upper limit of infrared luminosity ≲9 × 108L. Targeting this strongly lensed faint galaxy for follow-up Atacama Large Millimeter/submillimeter Array and JWST observations will be crucial to characterize the details of typical galaxy growth in the early Universe.

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DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Medium: X Size: Article No. 71
["Article No. 71"]
Sponsoring Org:
National Science Foundation
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