标题： 棒旋星系的星系气体盘的SPH模拟：银河系中心分子云的分布与动力学结构 显示英文标题

标题： SPH Simulations of Galactic Gaseous Disk with Bar: Distribution and Kinematic Structure of Molecular Clouds toward the Galactic Center

摘要： 我们进行了平滑粒子流体动力学（SPH）模拟，研究银河盘中的分子云对旋转棒的响应及其随后在银河系中心（GC）区域的演化。 在我们的模型中，银河系势能由三个轴对称分量（大质量晕、指数盘、紧凑核球）和一个非轴对称棒贡献。 这些分量在与棒一起旋转的参考框架中被认为是时间不变的。 由于棒的影响，一些显著特征如椭圆形外部环、螺旋臂、气体耗尽区和中心集中度已经形成。 旋转棒诱导了SPH粒子的非圆周运动，但流体力学碰撞倾向于抑制速度的随机成分。 SPH粒子的速度场与观测到的HCN（1-0）跃迁分子云的运动学一致；这些云被认为是非常致密的云。 然而，由CO追踪的云的l-v图与我们的SPH模拟的结果有很大不同，更类似于使用无碰撞粒子的模拟所得到的结果。 混合碰撞和无碰撞粒子的$l-v$图给出了更好的GC云在CO线中观测到的运动结构再现。 HCN云的运动学可以通过SPH粒子再现的事实表明，GC中的致密云是通过由旋转棒引起的云碰撞形成的。 显示英文摘要

摘要： We have performed Smoothed Particle Hydrodynamic (SPH) simulations to study the response of molecular clouds in the Galactic disk to a rotating bar and their subsequent evolution in the Galactic Center (GC) region. The Galactic potential in our models is contributed by three axisymmetric components (massive halo, exponential disk, compact bulge) and a non-axisymmetric bar. These components are assumed to be invariant in time in the frame corotating with the bar. Some noticeable features such as an elliptical outer ring, spiral arms, a gas-depletion region, and a central concentration have been developed due to the influence of the bar. The rotating bar induces non-circular motions of the SPH particles, but hydrodynamic collisions tend to suppress the random components of the velocity. The velocity field of the SPH particles is consistent with the kinematics of molecular clouds observed in HCN (1-0) transition; these clouds are thought to be very dense clouds. However, the l-v diagram of the clouds traced by CO is quite different from that of our SPH simulation, being more similar to that obtained from simulations using collisionless particles. The $l-v$ diagram of a mixture of collisional and collisionless particles gives better reproduction of the kinematic structures of the GC clouds observed in the CO line. The fact that the kinematics of HCN clouds can be reproduced by the SPH particles suggests that the dense clouds in the GC are formed via cloud collisions induced by rotating bar.