ALMA Reveals a Stable Rotating Gas Disk in a Paradoxical Low-mass, Ultradusty Galaxy at z = 4.274
Publikation: Bidrag til tidsskrift › Letter › Forskning › fagfællebedømt
Dokumenter
- Pope_2023_ApJL_951_L46
Forlagets udgivne version, 952 KB, PDF-dokument
We report ALMA detections of [C ii] and a dust continuum in Az9, a multiply imaged galaxy behind the Frontier Field cluster MACS J0717.5+3745. The bright [C ii] emission line provides a spectroscopic redshift of z = 4.274. This strongly lensed (μ = 7 ± 1) galaxy has an intrinsic stellar mass of only 2 × 109 M ⊙ and a total star formation rate of 26 M ⊙ yr−1 (∼80% of which is dust-obscured). Using public magnification maps, we reconstruct the [C ii] emission in the source plane to reveal a stable, rotation-dominated disk with V/σ = 5.3, which is >2× higher than predicted from simulations for similarly high-redshift, low-mass galaxies. In the source plane, the [C ii] disk has a half-light radius of 1.8 kpc and, along with the dust, is spatially offset from the peak of the stellar light by 1.4 kpc. Az9 is not deficient in [C ii]; L [C II]/L IR = 0.0027, consistent with local and high-redshift normal star-forming galaxies. While dust-obscured star formation is expected to dominate in higher-mass galaxies, such a large reservoir of dust and gas in a lower-mass disk galaxy 1.4 Gyr after the Big Bang challenges our picture of early galaxy evolution. Furthermore, the prevalence of such low-mass dusty galaxies has important implications for the selection of the highest-redshift dropout galaxies with JWST. As one of the lowest stellar mass galaxies at z > 4 to be detected in a dust continuum and [C ii], Az9 is an excellent laboratory in which to study early dust enrichment in the interstellar medium.
Originalsprog | Engelsk |
---|---|
Artikelnummer | L46 |
Tidsskrift | Astrophysical Journal Letters |
Vol/bind | 951 |
Udgave nummer | 2 |
Antal sider | 8 |
ISSN | 2041-8205 |
DOI | |
Status | Udgivet - 1 jul. 2023 |
Antal downloads er baseret på statistik fra Google Scholar og www.ku.dk
ID: 360681431