The Gas Content and Stripping of Local Group Dwarf Galaxies
Abstract
The gas content of the complete compilation of Local Group dwarf galaxies (119 within 2 Mpc) is presented using H I survey data. Within the virial radius of the Milky Way (224 kpc here), 53 of 55 dwarf galaxies are devoid of gas to limits of MH I < 104 M⊙. Within the virial radius of M31 (266 kpc), 27 of 30 dwarf galaxies are devoid of gas (with limits typically <105 M⊙). Beyond the virial radii of the Milky Way and M31, the majority of the dwarf galaxies have detected H I gas and H I masses higher than the limits. When the relationship between gas content and distance is investigated using a Local Group virial radius, more of the nondetected dwarf galaxies are within this radius (85 ± 1 of the 93 nondetected dwarf galaxies) than within the virial radii of the Milky Way and M31. Using the Gaia proper-motion measurements available for 38 dwarf galaxies, the minimum gas density required to completely strip them of gas is calculated. Halo densities between 10-5 and 5 × 10-4 cm-3 are typically required for instantaneous stripping at perigalacticon. When compared to halo density with radius expectations from simulations and observations, 80% of the dwarf galaxies with proper motions are consistent with being stripped by ram pressure at Milky Way pericenter. The results suggest that a diffuse gaseous galactic halo medium is important in quenching dwarf galaxies, and that a Local Group medium also potentially plays a role.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2021
- DOI:
- 10.3847/1538-4357/abe391
- arXiv:
- arXiv:2101.07809
- Bibcode:
- 2021ApJ...913...53P
- Keywords:
-
- Local Group;
- Dwarf galaxies;
- Galaxy quenching;
- Circumgalactic medium;
- Interstellar medium;
- Intergalactic medium;
- Andromeda Galaxy;
- Milky Way Galaxy;
- 929;
- 416;
- 2040;
- 1879;
- 847;
- 813;
- 39;
- 1054;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 26 pages, 7 figures, 3 tables, Accepted by ApJ