The Population of the Galactic Center Filaments: Position Angle Distribution Reveals a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane
Abstract
We have examined the distribution of the position angle (PA) of the Galactic center filaments with lengths L > 66″ and <66″ as well as their length distribution as a function of PA. We find bimodal PA distributions of the filaments, and long and short populations of radio filaments. Our PA study shows the evidence for a distinct population of short filaments with PA close to the Galactic plane. Mainly thermal, short-radio filaments (<66″) have PAs concentrated close to the Galactic plane within 60° < PA < 120°. Remarkably, the short filament PAs are radial with respect to the Galactic center at l < 0° and extend in the direction toward Sgr A*. On a smaller scale, the prominent Sgr E H II complex G358.7-0.0 provides a vivid example of the nearly radial distribution of short filaments. The bimodal PA distribution suggests a different origin for two distinct filament populations. We argue that the alignment of the short-filament population results from the ram pressure of a degree-scale outflow from Sgr A* that exceeds the internal filament pressure, and aligns them along the Galactic plane. The ram pressure is estimated to be 2 × 106 cm-3 K at a distance of 300 pc, requiring biconical mass outflow rate 10-4 M ⊙ yr-1 with an opening angle of ~40°. This outflow aligns not only the magnetized filaments along the Galactic plane but also accelerates thermal material associated with embedded or partially embedded clouds. This places an estimate of ~6 Myr as the age of the outflow.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2023
- DOI:
- 10.3847/2041-8213/acd54b
- arXiv:
- arXiv:2306.01071
- Bibcode:
- 2023ApJ...949L..31Y
- Keywords:
-
- Galactic center;
- Interstellar filaments;
- Non-thermal radiation sources;
- 565;
- 842;
- 1119;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 19 pages, 8 figures, ApJL (June 2nd, 2023)