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arXiv 0810.5158astro-ph
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Milky Way与N体模型的SDSS观测：位置-速度-金属丰度空间中恒星分布的比较

SDSS Observations of the Milky Way vs. N-body Models: A Comparison of Stellar Distributions in the Position-Velocity-Metallicity Space

S. Loebman, R. Roskar, Z. Ivezic

备注：
Presented at the "Classification and Discovery in Large Astronomical Surveys" meeting, Ringberg Castle, 14-17 October, 2008
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摘要：

通过最近的现代巡天获得的数据，能够详细研究从太阳附近一直到银河系外晕的多维空间中的恒星分布，该空间由空间坐标、速度和金属丰度构成。虽然这些结果代表了令人兴奋的观测突破，但它们的解释并不简单。例如，传统的薄盘和厚盘的分解预测金属丰度和运动学在距离银道面$\sim$ 1 kpc处有很强的相关性;然而，最近基于SDSS的工作表明盘星没有这种相关性。相反，金属丰度和旋转速度分布的变化可以使用非高斯函数来建模，这些函数保持其形状，并且仅随着与中平面的距离增加而移动。为了充分理解这些最近的观测结果，有必要与复杂的数值模型进行详细的比较。现代模拟有足够的分辨率和物理细节来研究恒星盘和球状体在大质量和宇宙年龄基线上的形成。我们讨论了各种观察到的地图和N-体模型预测的初步比较，并发现它们令人鼓舞。特别是，N-体盘模型Roškar等人。\cite{Roskar 2008}再现了磁盘尺度高度的变化，让人想起薄/厚磁盘分解，以及金属丰度和旋转速度梯度，而不是诱导后两个量的相关性，在定性与SDSS观测。

英文摘要：

The data obtained by the recent modern sky surveys enable detailed studies of the stellar distribution in the multi-dimensional space spanned by spatial coordinates, velocity and metallicity, from the solar neighborhood all the way out to the outer Milky Way halo. While these results represent exciting observational breakthroughs, their interpretation is not simple. For example, traditional decomposition of the thin and thick disks predicts a strong correlation in metallicity and kinematics at $\sim$1 kpc from the Galactic plane; however, recent SDSS--based work has demonstrated an absence of this correlation for disk stars. Instead, the variation of the metallicity and rotational velocity distributions can be modeled using non--Gaussian functions that retain their shapes and only shift as the distance from the mid--plane increases. To fully contextualize these recent observational results, a detailed comparison with sophisticated numerical models is necessary. Modern simulations have sufficient resolution and physical detail to study the formation of stellar disks and spheroids over a large baseline of masses and cosmic ages. We discuss preliminary comparisons of various observed maps and N--body model predictions and find them encouraging. In particular, the N--body disk models of Roškar et al. \cite{Roskar 2008} reproduce a change of disk scale height reminiscent of thin/thick disk decomposition, as well as metallicity and rotational velocity gradients, while not inducing a correlation of the latter two quantities, in qualitative agreement with SDSS observations.

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