On the Formation and Evolution of Disk Galaxies: Cosmological Initial Conditions and the Gravitational Collapse
On the Formation and Evolution of Disk Galaxies: Cosmological Initial Conditions and the Gravitational Collapse
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DOI：
10.1086/306136
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发表时间：
1997-10
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影响因子：
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通讯作者：
V. Avila-Reese;C. Firmani;X. Hernández
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文献类型：
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作者：
V. Avila-Reese;C. Firmani;X. Hernández
本文采用半解析方法和标准σ8 = 1冷暗物质（SCDM）宇宙学模型，研究了由原初高斯涨落产生的孤立暗物质星系晕的引力坍缩和维里化、结构以及全局和统计性质.首先，从原始密度涨落场的统计性质出发，生成可能的质量聚集历史。其次，这些历史被用作引力坍缩的初始条件。为了计算维里化系统的结构，我们推广了二次落体模型，允许任意的MAH和内部热运动。我们得到的平均晕密度分布与Navarro，Frenk，和白色的N体宇宙学模拟结果的拟合公式一致。讨论了密度廓线与观测数据的比较，并提出了一些可能的解决办法，发现在内部地区的分歧。我们的方法的结果，在考虑引力拖曳的重子物质，形成一个中心盘离心平衡后，表明经验塔利-费舍尔（TF）关系和它的散射可以解释通过初始宇宙学条件，至少对于孤立的系统。与观测值相比，σ8 = 1的SCDM模型产生的星系具有较高的速度，但当SCDM功率谱归一化为σ8 = 0.57时，发现与观测TF关系非常吻合，这表明该关系是观测星系分布功率谱在星系尺度上的自然延伸。理论TF散射与实测TF散射接近。TF关系的斜率实际上相对于自旋参数λ是不变的。
We use a semianalytical approach and the standard σ8 = 1 cold dark matter (SCDM) cosmological model to study the gravitational collapse and virialization, the structure, and the global and statistical properties of isolated dark matter galactic halos that emerge from primordial Gaussian fluctuations. First, from the statistical properties of the primordial density fluctuation field, the possible mass aggregation histories (MAHs) are generated. Second, these histories are used as the initial conditions of the gravitational collapse. To calculate the structure of the virialized systems, we have generalized the secondary infall model to allow arbitrary MAHs and internal thermal motions. The average halo density profiles we obtained agree with the profile derived as a fitting formula to results of N-body cosmological simulations by Navarro, Frenk, & White. The comparison of the density profiles with the observational data is discussed, and some possible solutions to the disagreement found in the inner regions are proposed. The results of our approach, after considering the gravitational dragging of the baryon matter that forms a central disk in centrifugal equilibrium, show that the empirical Tully-Fisher (TF) relation and its scatter can be explained through the initial cosmological conditions, at least for the isolated systems. The σ8 = 1 SCDM model produces galaxies with high velocities when compared with observations, but when the SCDM power spectrum is normalized to σ8 = 0.57, an excellent agreement with the observable TF relation is found, suggesting that this relation is the natural extension to galactic scales of the observed galaxy distribution power spectrum. The theoretical TF scatter is close to the measured one. The slope of the TF relation is practically invariant with respect to the spin parameter λ.