2023-06-02 ノースウェスタン大学
◆この新たな発見は、銀河中心の活動と関連していると考えられ、ブラックホールの自転や吸着円盤の方向性についての情報を提供する可能性があります。研究者たちは、この新たなフィラメントの起源や特性についてさらなる研究が必要であると述べています。
＜関連情報＞
- https://news.northwestern.edu/stories/2023/06/mysterious-dashes-revealed-in-milky-ways-center/
- https://iopscience.iop.org/article/10.3847/2041-8213/acd54b
銀河系中心部のフィラメントの母集団： 位置角度の分布から、Sgr A*からの流出が銀河面に沿って1度単位で平行移動していることがわかる The Population of the Galactic Center Filaments: Position Angle Distribution Reveals a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane
F. Yusef-Zadeh, R. G. Arendt, M. Wardle and I. Heywood
The Astrophysical Journal Letters Published: 2023 June 2
DOI:10.3847/2041-8213/acd54b
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 10−4M⊙ 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.
