Discovery of an Isolated Dark Dwarf Galaxy in the Nearby Universe
Abstract
Based on a new H I survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with the Pan-STARRS1 images, we identified an isolated H I cloud without any optical counterpart, named FAST J0139+4328. The newly discovered H I cloud appears to be a typical disk galaxy since it has a double-peak shape in the global H I profile and an S-like rotation structure in the velocity-position diagram. Moreover, this disk galaxy has an extremely low absolute magnitude (M B > -10.0 mag) and stellar mass (<6.9 ×105 M ⊙). Furthermore, we obtained that the H I mass of this galaxy is (8.3 ± 1.7) ×107 M ⊙, and the dynamical mass to total baryonic mass ratio is 47 ± 27, implying that dark matter dominates over baryons in FAST J0139+4328. These findings provide observational evidence that FAST J0139+4328 is an isolated dark dwarf galaxy with a redshift of z = 0.0083. This is the first time that an isolated dark galaxy has been detected in the nearby universe.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2023
- DOI:
- 10.3847/2041-8213/acb932
- arXiv:
- arXiv:2302.02646
- Bibcode:
- 2023ApJ...944L..40X
- Keywords:
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- Extragalactic astronomy;
- 506;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 13 pages, 3 figures, Accepted for publication in the ApJ Letters