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arXiv 1810.12296astro-ph.GAastro-ph.SR
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大型光谱巡天的选择函数

Selection functions of large spectroscopic surveys

Alexey Mints, Saskia Hekker

摘要:

上下文大型光谱巡天为探索我们的银河系开辟了道路。为了利用这些巡天的数据来了解银河系的恒星星族,我们需要确保巡天中包含的恒星是潜在恒星族的代表性子集。如果不考虑选择函数,结果可能反映的是选择函数的性质,而不是潜在的恒星星族的性质。目标。在这项工作中,我们介绍了一种方法来估计一个给定的光谱调查的选择函数。我们将这种方法应用于大样本的公共光谱调查。方法.我们应用中值分割分箱算法在颜色星等空间中对观测到的恒星进行分箱。与传统使用的2D直方图相比,这种方法产生更低的不确定性和更低的选择函数估计偏差。我们运行一组模拟来验证该方法并校准它包含的一个自由参数。这些模拟使我们能够测试该方法的精度和准确性。结果我们生产和出版的估计值和不确定性的选择功能的大样本的公共光谱调查。我们公开发布用于生成选择函数估计的代码。结论.选择函数对巡天中恒星的距离模量和金属丰度分布的影响对于空间覆盖范围小且很大程度上不均匀的巡天很重要。对于具有连续空间覆盖的调查,选择函数的影响几乎可以忽略不计。

英文摘要:

Context. Large spectroscopic surveys open the way to explore our Galaxy. In order to use the data from these surveys to understand the Galactic stellar population, we need to be sure that stars contained in a survey are a representative subset of the underlying population. Without the selection function taken into account, the results might reflect the properties of the selection function rather than those of the underlying stellar population. Aims. In this work, we introduce a method to estimate the selection function for a given spectroscopic survey. We apply this method to a large sample of public spectroscopic surveys. Methods. We apply a median division binning algorithm to bin observed stars in the colour-magnitude space. This approach produces lower uncertainties and lower biases of the selection function estimate as compared to traditionally used 2D-histograms. We run a set of simulations to verify the method and calibrate the one free parameter it contains. These simulations allow us to test the precision and accuracy of the method. Results. We produce and publish estimated values and uncertainties of selection functions for a large sample of public spectroscopic surveys. We publicly release the code used to produce the selection function estimates. Conclusions. The effect of the selection function on distance modulus and metallicity distributions of stars in surveys is important for surveys with small and largely inhomogeneous spatial coverage. For surveys with contiguous spatial coverage the effect of the selection function is almost negligible.

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