The Identification of a Dusty Multiarm Spiral Galaxy at z = 3.06 with JWST and ALMA
Abstract
Spiral arms serve crucial purposes in star formation and galaxy evolution. In this paper, we report the identification of "A2744-DSG-z3," a dusty, multiarm spiral galaxy at z = 3.059 using the James Webb Space Telescope (JWST) NIRISS imaging and grism spectroscopy. A2744-DSG-z3 was discovered as a gravitationally lensed submillimeter galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA). This is the most distant stellar spiral structure seen thus far, consistent with cosmological simulations that suggest z ≈ 3 as the epoch when spirals emerge. Thanks to the gravitational lensing and excellent spatial resolution of JWST, the spiral arms are resolved with a spatial resolution of ≈290 pc. Based on spectral energy distribution fitting, the spiral galaxy has a delensed star formation rate of 85 ± 30 M ⊙ yr-1, and a stellar mass of ≈1010.6 M ⊙, indicating that A2744-DSG-z3 is a main-sequence galaxy. After fitting the spiral arms, we find a stellar effective radius (R e,star) of 5.0 ± 1.5 kpc. Combining with ALMA measurements, we find that the effective radii ratio between dust and stars is ≈0.4, similar to those of massive star‑forming galaxies (SFGs) at z ~ 2, indicating a compact dusty core in A2744-DSG-z3. Moreover, this galaxy appears to be living in a group environment: including A2744-DSG-z3, at least three galaxies at z = 3.05-3.06 are spectroscopically confirmed by JWST/NIRISS and ALMA, residing within a lensing-corrected projected scale of ≈70 kpc. This, along with the asymmetric brightness profile, further suggests that the spiral arms may be triggered by minor-merger events at z ≳ 3.
- Publication:
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The Astrophysical Journal
- Pub Date:
- January 2023
- DOI:
- 10.3847/2041-8213/aca652
- arXiv:
- arXiv:2208.08473
- Bibcode:
- 2023ApJ...942L...1W
- Keywords:
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- Spiral galaxies;
- 1560;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Main text 9 pages, four figures in the main text, and three figures in the appendix