| 1. |
- Fudamoto, Yoshinobu, et al.
(författare)
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The Extended [C II] under Construction? : Observation of the Brightest High-z Lensed Star-forming Galaxy at z=6.2
- 2024
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 961:1
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Tidskriftsartikel (refereegranskat)abstract
- We present results of [C ii] 158 μm emission line observations, and report the spectroscopic redshift confirmation of a strongly lensed (μ ∼ 20) star-forming galaxy, MACS0308-zD1 at z = 6.2078 ± 0.0002. The [C ii] 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 [C ii] has a velocity full width half maximum (FWHM) of 110 ± 20 km s−1, while broader [C ii] is seen with an FWHM of 230 ± 50 km s−1. The broader [C ii] component is blueshifted (−80 ± 20 km s−1) with respect to the narrow [C ii] component, and has a morphology that extends beyond the UV-bright clump. We find that, while the narrow [C ii] 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 of λ158μm dust 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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| 2. |
- Hsiao, Tiger Yu-Yang, et al.
(författare)
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JWST Reveals a Possible z similar to 11 Galaxy Merger in Triply Lensed MACS0647-JD
- 2023
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 949:2
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Tidskriftsartikel (refereegranskat)abstract
- MACS0647-JD is a triply lensed z similar to 11 galaxy originally discovered with the Hubble Space Telescope. The three lensed images are magnified by factors of similar to 8, 5, and 2 to AB mag 25.1, 25.6, and 26.6 at 3.5 mu m. The brightest is over a magnitude brighter than other galaxies recently discovered at similar redshifts z > 10 with JWST. Here, we report new JWST imaging that clearly resolves MACS0647-JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. The brighter larger component "A" is intrinsically very blue (ss similar to-2.6 +/- 0.1), likely due to very recent star formation and no dust, and is spatially extended with an effective radius similar to 70 +/- 24 pc. The smaller component "B" (r similar to 20-+ 58 pc) appears redder (ss similar to-2 +/- 0.2), likely because it is older (100-200 Myr) with mild dust extinction (AV similar to 0.1 mag). With an estimated stellar mass ratio of roughly 2:1 and physical projected separation similar to 400 pc, we may be witnessing a galaxy merger 430 million years after the Big Bang. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be dissimilar, which is also suggested by the spectral energy distribution fitting, suggesting they formed further apart. We also identify a candidate companion galaxy "C" similar to 3 kpc away, likely destined to merge with A and B. Upcoming JWST Near Infrared Spectrograph observations planned for 2023 January will deliver spectroscopic redshifts and more physical properties for these tiny magnified distant galaxies observed in the early universe.
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| 3. |
- Welch, Brian, et al.
(författare)
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JWST Imaging of Earendel, the Extremely Magnified Star at Redshift z=6.2
- 2022
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 2041-8213. ; 940
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Tidskriftsartikel (refereegranskat)abstract
- The gravitationally lensed star WHL 0137-LS, nicknamed Earendel, was identified with a photometric redshift z (phot) = 6.2 +/- 0.1 based on images taken with the Hubble Space Telescope. Here we present James Webb Space Telescope (JWST) Near Infrared Camera images of Earendel in eight filters spanning 0.8-5.0 mu m. In these higher-resolution images, Earendel remains a single unresolved point source on the lensing critical curve, increasing the lower limit on the lensing magnification to mu > 4000 and restricting the source plane radius further to r < 0.02 pc, or similar to 4000 au. These new observations strengthen the conclusion that Earendel is best explained by an individual star or multiple star system and support the previous photometric redshift estimate. Fitting grids of stellar spectra to our photometry yields a stellar temperature of T (eff) similar to 13,000-16,000 K, assuming the light is dominated by a single star. The delensed bolometric luminosity in this case ranges from log(L)=5.8 L-theta, which is in the range where one expects luminous blue variable stars. Follow-up observations, including JWST NIRSpec scheduled for late 2022, are needed to further unravel the nature of this object, which presents a unique opportunity to study massive stars in the first billion years of the universe.
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