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arXiv 1002.3098astro-ph.COastro-ph.GA
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边缘盘星系-IV的暗物质晕形状。UGC 7321

The dark matter halo shape of edge-on disk galaxies - IV. UGC 7321

J. C. O'Brien, K. C. Freeman, P. C. van der Kruit

摘要:

这是一系列论文中的第四篇,我们试图对盘星系中暗晕的扁平化进行限制。为此目的,我们观察到的HI在边缘上的星系,在那里它是在原则上可以测量的力场在晕垂直和径向分别从气体层耀斑和旋转曲线分解。我们分析了HI通道图,以准确测量描述HI运动学和3D分布的所有四个功能:径向HI表面密度、HI垂直厚度、旋转曲线和HI速度分散。在本文中,我们分析这些数据的边缘星系UGC 7321。我们测量了恒星质量分布($M=3\times10^8$ \msun与$M/L_R\lesim0.2$),发现气体盘的垂直力在所有半径上都占主导地位。我们发现,垂直力把一个更强的约束恒星的质量比比旋转曲线分解。由耀斑和速度弥散得到的垂直力场的拟合表明,UGC 7321具有球形晕密度分布和$q = c/a = 1.0 \pm 0.1$的平坦化。

英文摘要:

This is the fourth paper in a series in which we attempt to put constraints on the flattening of dark halos in disk galaxies. We observed for this purpose the HI in edge-on galaxies, where it is in principle possible to measure the force field in the halo vertically and radially from gas layer flaring and rotation curve decomposition respectively. We have analysed the HI channel maps to accurately measure all four functions that describe the HI kinematics and 3D distribution: the radial HI surface density, the HI vertical thickness, the rotation curve and the HI velocity dispersion. In this paper we analyse these data for the edge-on galaxy UGC7321. We measured the stellar mass distribution ($M=3\times10^8$ \msun with $M/L_R\lesim0.2$), finding that the vertical force of the gas disk dominates the stellar disk at all radii. We find that the vertical force puts a much stronger constraint on the stellar mass-to-light ratio than rotation curve decomposition. Fitting of the vertical force field derived from the flaring and velocity dispersion of the HI revealed that UGC7321 has a spherical halo density distribution with a flattening of $q = c/a = 1.0 \pm 0.1$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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