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arXiv 1302.7253astro-ph.GA
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磁场:对银河系自转曲线的影响

Magnetic fields: Impact on the rotation curve of the Galaxy

F. J. Sanchez-Salcedo, A. Santillan

摘要:

我们量化的影响磁场,宇宙射线和气体压力的HI气体在银河系中的旋转速度,在银河系的距离之间的Rsun和2 Rsun。磁场由两个分量建模;主要方位角磁分量和小尺度缠结场。我们构建了一系列合理的轴对称模型,与从无线电同步加速器数据推断的总磁场的强度一致。在一个真实的银河系圆盘中,湍流运动、宇宙射线和缠结的湍流场产生的压力为圆盘提供径向支撑。大规模(有序)磁场可能会或可能不会提供支持磁盘,这取决于局部径向梯度的方位场。我们发现,观测约束模型,磁力不能明显改变HI气体的切向速度在银河系的距离为2 Rsun。

英文摘要:

We quantify the effects of magnetic fields, cosmic rays and gas pressure on the rotational velocity of HI gas in the Milky Way, at galactic distances between Rsun and 2Rsun. The magnetic field is modelled by two components; a mainly azimuthal magnetic component and a small-scale tangled field. We construct a range of plausible axisymmetric models consistent with the strength of the total magnetic field as inferred from radio synchrotron data. In a realistic Galactic disk, the pressure by turbulent motions, cosmic rays and the tangled turbulent field provide radial support to the disk. Large-scale (ordered) magnetic fields may or may not provide support to the disk, depending on the local radial gradient of the azimuthal field. We show that for observationally constrained models, magnetic forces cannot appreciably alter the tangential velocity of HI gas within a galactic distance of 2Rsun.

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