论文标题
银河系磁盘中动态螺旋扰动的强度
The Strength of the Dynamical Spiral Perturbation in the Galactic Disk
论文作者
论文摘要
在银河系中间平面内，发光红色巨星的平均半乳突径向速度$ \ langle V_ {r} \ rangle（r，φ）$ $我们应用了对数螺旋的简单稳态玩具模型来解释这些观察结果，并找到良好的定性和定量匹配。假设引力电位扰动的幅度与磁盘的表面质量密度相称，我们估计表面质量密度振幅为$σ_{\ rm max}（r _ {\ odot}） $ω_ {\ mathrm p} = 12 \，\ rm km \，s^{ - 1} \，kpc^{ - 1} $的固定模式速度。结合局部磁盘密度，这意味着在太阳半径处的臂和臂间区域之间的表面质量密度对比约为$ \ pm 10 \％$，并且增加了较大的半径。我们的模型将动态螺旋臂的螺距角度约为$ 12^{\ circ} $。
The mean Galactocentric radial velocities $\langle v_{R}\rangle(R,φ)$ of luminous red giant stars within the mid-plane of the Milky Way reveal a spiral signature, which could plausibly reflect the response to a non-axisymmetric perturbation of the gravitational potential in the Galactic disk. We apply a simple steady-state toy model of a logarithmic spiral to interpret these observations, and find a good qualitative and quantitative match. Presuming that the amplitude of the gravitational potential perturbation is proportionate to that in the disk's surface mass density, we estimate the surface mass density amplitude to be $Σ_{\rm max} (R_{\odot})\approx 5.5\,\rm M_{\odot}\,pc^{-2}$ at the solar radius when choosing a fixed pattern speed of $Ω_{\mathrm p}=12\,\rm km\,s^{-1}\,kpc^{-1}$. Combined with the local disk density, this implies a surface mass density contrast between the arm and inter-arm regions of approximately $\pm 10\%$ at the solar radius, with an increases towards larger radii. Our model constrains the pitch angle of the dynamical spiral arms to be approximately $12^{\circ}$.
