论文标题

Gaia数据版本2中的轴向不对称研究产生了银河棒的模式速度

Axial Asymmetry Studies in Gaia Data Release 2 Yield the Pattern Speed of the Galactic Bar

论文作者

Hinkel, Austin, Gardner, Susan, Yanny, Brian

论文摘要

我们最近在附近的轴向对称性破裂($ d <3 \,{\ rm kpc} $)恒星计数对垂直的恒星轨道的扭曲敏感,并且与垂直的恒星轨道的扭曲,并且与钢筋内部和外部杆的方向平行。 Using the location of the sign flip in the left-right asymmetry in stars counts about the anticenter line to determine the OLR radius $R_{\rm OLR}$, and treating the bar as if it were a weakly non-axisymmetric effect, we use $R_{\rm OLR}$ and recent measurements of the Galactic rotation curve and the Sun-Galactic-center distance $ r_ {0} $确定银河栏的模式速度$ω_ {\ rm p} $,以及银河旋转半径$ r _ {\ rm cr} $。从我们的不对称测量中删除了大小麦芽云的效果后,我们发现$ r _ {\ rm olr} =(0.96 \ pm 0.03)r_0 = 7.85 \ pm 0.25 \ pm 0.25 \ \ \ \ \ \ \ rm kpc $,$ 2. s^{ - 1} \ kpc^{ - 1} $,$ r _ {\ rm cr} =(0.58 \ pm 0.04)r_0 = 4.76 \ pm 0.27 \ pm 0.27 \ \ rm kpc $,如我们所示,我们可能会表明,我们也可能会表明,我们可能会表明较弱的证据,也可能会效果效果。

Our recent studies of axial-symmetry breaking in the nearby ($d <3 \,{\rm kpc}$) star counts are sensitive to the distortions of stellar orbits perpendicular and parallel to the orientation of the bar just within and beyond the outer Lindblad resonance (OLR) radius. Using the location of the sign flip in the left-right asymmetry in stars counts about the anticenter line to determine the OLR radius $R_{\rm OLR}$, and treating the bar as if it were a weakly non-axisymmetric effect, we use $R_{\rm OLR}$ and recent measurements of the Galactic rotation curve and the Sun-Galactic-center distance $R_{0}$ to determine the pattern speed $Ω_{\rm p}$ of the Galactic bar, as well as the Galactic corotation radius $R_{\rm CR}$. After removing the effect of the Large and Small Magellanic clouds from our asymmetry measurement, we find that $R_{\rm OLR}=(0.96 \pm 0.03)R_0 = 7.85 \pm 0.25 \ \rm kpc$, $Ω_{\rm p} = 49.3 \pm 2.2 \ \rm km \ s^{-1} \ kpc^{-1}$, $R_{\rm CR}=(0.58 \pm 0.04)R_0 = 4.76 \pm 0.27 \ \rm kpc$, revealing, as we shall show, that the Milky Way's bar is likely both weak and fast, though we also note possible evidence for non-steady-state effects in the bar region.

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