AI 中文总结
该研究利用可微流体动力学框架，通过CO经度-速度数据建模银河系棒状气体流动，在棒状模式速度参数空间约束低损耗区域，经模拟验证后应用于实际数据，证明了此建模方法对银河系棒状模型测试及多参数正向建模的可行性。
AI 中文摘要
我们提出了一个可微流体动力学框架，用于对银河系中的棒状气体流动进行建模，并根据银河系经度-速度数据在棒状模式速度参数空间中约束广泛的低损耗区域。该方法在固定的棒状势场中演化中性气体盘，将其投影到经度-速度（$\ell$-$v$）空间，并使用应用于处理和掩码地图的余弦距离损失比较预测地图和目标地图。这强调了大规模形态而非绝对发射尺度。由于正向模型是可微的，可以计算相对于棒状模式速度的梯度，并用于在可观测空间中进行直接优化。我们用自洽流体动力学模拟和由具有更现实星际介质物理的不同求解器生成的独立模拟验证了该方法。这些测试恢复或识别了接近输入模式速度的低损耗区域，表明该方法在$\ell$-$v$空间中捕获了连贯的棒驱动结构。然后，我们将该框架应用于银河系内部观测到的CO $\ell$-$v$结构。数据产生了广泛的低损耗区域，而不是唯一的最佳拟合值。这些区域包括中等模式速度，$|\Omega_{\rm b}|\sim30$-$40\,{\rm km\,s^{-1}\,kpc^{-1}}$，与当前恒星动力学约束一致，尽管它们的位置取决于气体响应时间和视角。这首次应用证明了银河系气体的可微流体动力学建模作为对银河系棒状模型的独立运动学测试以及朝着位置-位置-速度空间中的多参数正向建模迈出的一步的可行性。
英文摘要
We present a differentiable hydrodynamical framework for modeling barred gas flow in the Milky Way and constraining broad low-loss regions in bar-pattern-speed parameter space from Galactic longitude--velocity data. The method evolves a neutral-gas disk in a fixed barred potential, projects it into longitude--velocity ($\ell$--$v$) space, and compares predicted and target maps using a cosine-distance loss applied to processed and masked maps. This emphasizes large-scale morphology rather than the absolute emission scale. Because the forward model is differentiable, gradients with respect to the bar pattern speed can be computed and used for direct optimization in observable space. We validate the method with self-consistency hydrodynamical mocks and with an independent mock generated by a different solver with more realistic interstellar-medium physics. These tests recover or identify low-loss regions near the input pattern speed, showing that the method captures coherent bar-driven structures in $\ell$--$v$ space. We then apply the framework to the observed CO $\ell$--$v$ structure of the inner Milky Way. The data yield broad low-loss regions rather than a unique best-fitting value. These regions include moderate pattern speeds, $|Ω_{\rm b}|\sim30$--$40\,{\rm km\,s^{-1}\,kpc^{-1}}$, consistent with current stellar-dynamical constraints, although their location depends on the gas response time and viewing angle. This first application demonstrates the feasibility of differentiable hydrodynamical modeling of Galactic gas as an independent kinematic test of barred Milky Way models and as a step toward multi-parameter forward modeling in position--position--velocity space.
CommentsAccepted for publication in PASJ
