Unavoidable Selection Effects in the Analysis of Faint Galaxies in the Hubble Deep Field: Probing the Cosmology and Merger History of Galaxies
Unavoidable Selection Effects in the Analysis of Faint Galaxies in the Hubble Deep Field: Probing the Cosmology and Merger History of Galaxies
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哈勃深场微弱星系分析中不可避免的选择效应：探索宇宙学和星系合并历史
DOI：
10.1086/309313
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Y. Yoshii
中科院分区：
文献类型：
--
作者：
T. Totani;Y. Yoshii
我们提出了一个详细的分析，在哈勃深场（HDF）暗星系的数量计数和光度红移分布，特别注意选择效应，包括宇宙学的星系表面亮度的调光，在这个领域的观测条件下。我们发现一个相当不同的结果，从以前的研究，忽略了选择的影响，因此，这些影响应考虑在分析中。我们发现，爱因斯坦-德西特（EdS）宇宙中星系的纯光度演化（PLE）模型预测的计数比在微弱星等极限下观测到的计数要小得多，相差10倍以上，因此，当参数化为η * η（1 + z）η时，必须调用η = 3-4的非常强的星系数演化来再现I814计数。然而，我们发现，这种强大的星系合并过程中的数量演变不能解释陡峭的斜率的B450和V606计数，这是严重不符合他们的光度红移分布。我们发现，这些困难仍然存在于一个开放的宇宙与Ω0 <$0.2，只有当我们调用一个Λ主导的平坦宇宙，在检查各种系统的不确定性在模拟星系的形成和演化。目前的分析振兴的做法，使用微弱数计数作为一个重要的宇宙学测试，给出了一个论点反对EdS宇宙，并建议加速宇宙膨胀的真空能量密度。尽管在Λ主导的宇宙中，η ≥ 1的星系的适度数量演化仍然是必要的，但HDF数据拒绝了η > 1的更强数量演化，这对星系的合并历史产生了强烈的约束。
We present a detailed analysis of the number count and photometric redshift distribution of faint galaxies in the Hubble Deep Field (HDF), paying special attention to selection effects, including the cosmological dimming of the surface brightness of galaxies, under the observational conditions employed in this field. We find a considerably different result from previous studies that ignore selection effects; these effects should therefore be taken into account in the analysis. We find that the model of pure luminosity evolution (PLE) of galaxies in the Einstein-de Sitter (EdS) universe predicts much smaller counts than those observed at faint magnitude limits, by a factor of more than 10, so that a very strong number evolution of galaxies with η ≳ 3-4 must be invoked to reproduce the I814 counts, when parametrized as ϕ* ∝ (1 + z)η. However, we show that such a strong number evolution under realistic merging processes of galaxies cannot explain the steep slope of the B450 and V606 counts, and it is seriously inconsistent with their photometric redshift distribution. We find that these difficulties still persist in an open universe with Ω0 ≳ 0.2, and are resolved only when we invoke a Λ-dominated flat universe, after examining various systematic uncertainties in modeling the formation and evolution of galaxies. The present analysis revitalizes the practice of using faint number counts as an important cosmological test, giving one of the arguments against the EdS universe, and suggests acceleration of the cosmic expansion by vacuum energy density. While a modest number evolution of galaxies with η ≲ 1 is still necessary even in a Λ-dominated universe, a stronger number evolution with η > 1 is rejected from the HDF data, giving a strong constraint on the merger history of galaxies.