| 1. |
- Fujimoto, Seiji, et al.
(author)
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ALMA Lensing Cluster Survey: Bright [C ii] 158 mu m Lines from a Multiply Imaged Sub-L* Galaxy at z=6.0719
- 2021
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 911:2
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Research review (peer-reviewed)abstract
- We present bright [C ii] 158 mu m line detections from a strongly magnified and multiply imaged (mu similar to 20-160) sub-L* (MUV=-19.75-0.44+0.55) Lyman-break galaxy (LBG) at z = 6.0719 +/- 0.0004, drawn from the ALMA Lensing Cluster Survey (ALCS). Emission lines are identified at 268.7 GHz at >= 8 sigma exactly at the positions of two multiple images of the LBG, behind the massive galaxy cluster RXCJ0600-2007. Our lens models, updated with the latest spectroscopy from VLT/MUSE, indicate that a sub region of the LBG crosses the caustic, and is lensed into a long (similar to 6 '') arc with a local magnification of mu similar to 160, for which the [C ii] line is also significantly detected. The source plane reconstruction resolves the interstellar medium (ISM) structure, showing that the [C ii] line is co-spatial with the rest-frame UV continuum at a scale of similar to 300 pc. The [C ii] line properties suggest that the LBG is a rotation-dominated system, whose velocity gradient explains a slight difference in redshifts between the whole LBG and its sub-region. The star formation rate (SFR)-L-[CII] relations, for whole and sub-regions of the LBG, are consistent with those of local galaxies. We evaluate the lower limit of the faint-end of the [C ii] luminosity function at z = 6, finding it to be consistent with predictions from semi-analytical models and from the local SFR-L-[CII] relation with a SFR function at z = 6. These results imply that the local SFR-L-[CII] relation is universal for a wide range of scales, including the spatially resolved ISM, the whole region of the galaxy, and the cosmic scale, even in the epoch of reionization.
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| 2. |
- Sun, Fengwu, et al.
(author)
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Extensive Lensing Survey of Optical and Near-infrared Dark Objects (El Sonido): HST H-faint Galaxies behind 101 Lensing Clusters
- 2021
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 922:2
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Journal article (peer-reviewed)abstract
- We present a Spitzer/IRAC survey of H-faint (H-160 greater than or similar to 26.4, < 5 sigma) sources in 101 lensing cluster fields. Across a CANDELS/Wide-like survey area of similar to 648 arcmin(2) (effectively similar to 221 arcmin(2) in the source plane), we have securely discovered 53 sources in the IRAC Channel-2 band (CH2, 4.5 mu m; median CH2 = 22.46 +/- 0.11 AB mag) that lack robust HST/WFC3-IR F160W counterparts. The most remarkable source in our sample, namely ES-009 in the field of Abell 2813, is the brightest H-faint galaxy at 4.5 mu m known so far (CH2 = 20.48 +/- 0.03 AB mag). We show that the H-faint sources in our sample are massive (median M-star = 10 10.3 +/- 0.3 M-circle dot, star-forming (median star formation rate =1001 M-circle dot yr(-1)), and dust-obscured (A(v) = 2.6 +/- 0.3) galaxies around a median photometric redshift of z = 3.9 +/- 0.4. The stellar continua of 14 H-faint galaxies can be resolved in the CH2 band, suggesting a median circularized effective radius (R-e,R-circ; lensing corrected) of 1.9 +/- 0.2 kpc and <1.5 kpc for the resolved and whole samples, respectively. This is consistent with the sizes of massive unobscured galaxies at z similar to 4, indicating that H-faint galaxies represent the dusty tail of the distribution of a wider galaxy population. Comparing with the ALMA dust continuum sizes of similar galaxies reported previously, we conclude that the heavy dust obscuration in H-faint galaxies is related to the compactness of both stellar and dust continua (R-e,R-circ similar to 1 kpc). These H-faint galaxies make up 161 3 % of the galaxies in the stellar-mass range of 10(10) - 10(11.2) M-circle dot at z = 3 similar to 5, contributing to 8(-4)(+8)% of the cosmic star formation rate density in this epoch and likely tracing the early phase of massive galaxy formation.
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