Bar Diagnostics in Edge-on Spiral Galaxies. II. Hydrodynamical Simulations
Bar Diagnostics in Edge-on Spiral Galaxies. II. Hydrodynamical Simulations
复制标题
边缘螺旋星系中的棒诊断。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Martin Bureau
中科院分区：
文献类型：
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作者：
E. Athanassoula;Martin Bureau
我们开发了基于气体运动学的诊断学，以识别边缘螺旋星系中条状星系的存在，并确定其方向。我们使用位置-速度图(PVD)，通过投影边缘上的二维流体动力学模拟来模拟阻挡星系势中的气体流动。我们发现，当核螺旋形成时，在核螺旋签名和盘外部签名之间的PVD中的间隙的存在可靠地指示了棒的存在。这一差距是由于模拟中激波和流入的存在，导致外沙坝区域的气体耗尽。如果PVD中不存在核螺旋信号，则只能使用间接论据来论证棒的存在。核螺旋的标志的形状，以及较小程度的外棒区域的形状，允许确定棒相对于视线的方向。灰尘的存在也有助于区分条两侧的视角。覆盖很大一部分参数空间的模拟限制了观测到的星系的条状属性和质量分布。最强的限制来自于PVD中是否存在核螺旋的特征。
We develop diagnostics based on gas kinematics to identify the presence of a bar in an edge-on spiral galaxy and determine its orientation. We use position-velocity diagrams (PVDs) obtained by projecting edge-on two-dimensional hydrodynamical simulations of the gas flow in a barred galaxy potential. We show that when a nuclear spiral is formed, the presence of a gap in the PVDs, between the signature of the nuclear spiral and that of the outer parts of the disk, reliably indicates the presence of a bar. This gap is due to the presence of shocks and inflows in the simulations, leading to a depletion of the gas in the outer bar region. If no nuclear spiral signature is present in a PVD, only indirect arguments can be used to argue for the presence of a bar. The shape of the signature of the nuclear spiral, and to a lesser extent that of the outer bar region, allows a determination of the orientation of the bar with respect to the line of sight. The presence of dust can also help to discriminate between viewing angles on either side of the bar. Simulations covering a large fraction of parameter space constrain the bar properties and mass distribution of observed galaxies. The strongest constraint comes from the presence or absence of the signature of a nuclear spiral in the PVD.