Radial distributions of arm-gas offsets as an observational test of spiral theories
Radial distributions of arm-gas offsets as an observational test of spiral theories
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DOI：
10.1093/pasj/psv048
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发表时间：
2015-05
期刊：
影响因子：
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通讯作者：
J. Baba;K. Morokuma-Matsui;F. Egusa
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文献类型：
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作者：
J. Baba;K. Morokuma-Matsui;F. Egusa
根据旋臂的寿命，盘状星系中的恒星旋臂理论可以分为两类。虽然准静态密度波理论假设螺旋是刚性旋转的、长寿命的模式，但动态螺旋理论预测螺旋是差异旋转的、瞬时的、反复出现的模式。为了区分这两种螺旋模型与观测值，我们用稳态螺旋模型和动态螺旋模型进行了水动力模拟。定常螺旋模型中的流体力学模拟表明，尘埃带相对于恒星螺旋臂的位置(下称臂-气体偏移量)取决于半径，而与螺旋的强度和俯仰角以及星际介质(ISM)的模型无关。相反，我们发现动态螺旋模型没有显示出系统的臂-气体偏移量的径向依赖关系。ARM-GAS偏置径向剖面法和其他检验方法将有助于我们区分观测到的螺旋星系中的两种螺旋模型。
Theories of stellar spiral arms in disk galaxies can be grouped into two classes based on the longevity of a spiral arm. Although the quasi-stationary density wave theory supposes that spirals are rigidly-rotating, long-lived patterns, the dynamic spiral theory predicts that spirals are differentially-rotating, transient, recurrent patterns. In order to distinguish between the two spiral models from observations, we performed hydrodynamic simulations with steady and dynamic spiral models. Hydrodynamics simulations in steady spiral models demonstrated that the dust lane locations relative to the stellar spiral arms (hereafter, arm-gas offsets) depend on radius, regardless of the strength and pitch angle of the spiral and the model of the inter-stellar medium (ISM). In contrast, we found that the dynamic spiral models show no systematic radial dependence of the arm-gas offsets. The arm-gas offset radial profile method, together with the other test methods, will help us to distinguish between the two spiral models in observed spiral galaxies.