Detection of the Keplerian decline in the Milky Way rotation curve

作者：Yongjun Jiao, F. Hammer, Haifeng Wang, Jianling Wang, P. Amram, L. Chemin, Yanbin Yang · 发表于：Astronomy and Astrophysics · 年份：2023 · DOI：10.1051/0004-6361/202347513 · 被引用次数：100 · 研究领域：Stellar, planetary, and galactic studies、Astrophysics and Star Formation Studies、Gamma-ray bursts and supernovae

Our position inside the Galactic disc has previously prevented us from establishing an accurate rotation curve (RC). The advent of Gaia and its third data release ( Gaia DR3) made it possible to specify the RC up to twice the optical radius. We aim to establish a new RC of the Galaxy from the Gaia DR3 by drastically reducing systematic uncertainties. Our goal is to provide a new estimate of the mass of the Galaxy. We compared different estimates, established a robust assessment of the systematic uncertainties, and addressed differences in methodologies, particularly regarding distance estimates. We find a sharply decreasing RC for the Milky Way; the decrease in velocity between 19.5 and 26.5 kpc is approximately 30 km s −1 . We identify, for the first time, a Keplerian decline of the RC, starting at ∼19 kpc and ending at ∼26.5 kpc from the Galaxy centre, while a flat RC is rejected with a significance of 3 σ . The total mass is revised downwards to 2.06 −0.13 +0.24 × 10 11 M ⊙ , which is in agreement with the absence of a significant mass increase at radii larger than 19 kpc. We evaluated the upper limit on the total mass by considering the upper values of velocity measurements, which leads to a strict, unsurpassable limit of 5.4 × 10 11 M ⊙ .