Measuring omega(0) using cluster evolution
Measuring omega(0) using cluster evolution
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DOI：
10.1046/j.1365-8711.1998.01713.x
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发表时间：
1998-02
影响因子：
4.8
通讯作者：
V. Eke;S. Cole;C. Frenk;Patrick Henry
中科院分区：
文献类型：
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作者：
V. Eke;S. Cole;C. Frenk;Patrick Henry
星系团丰度的演化敏感地取决于宇宙学密度参数 Omega_0 的值。最近的 ASCA 数据被用来量化通过 X 射线温度函数测量的这种演变。对累积温度函数的 chi^2 最小化拟合以及最大似然估计（需要对星团光度进行额外假设）导致估计 Omega_0 \approx 0.45+/-0.2（1-sigma 统计误差）。考虑了各种系统不确定性，但这些不确定性都没有显着提高 Omega_0=1 的概率。这些结论对于有或没有宇宙学常数的模型都成立。统计不确定性至少与此处考虑的单个系统误差一样大，这表明对遥远星团的额外温度测量将允许改进这一估计。还提出并暂时应用了一种使用最高红移星团对 Omega_0 设置上限的替代方法，结果可以在 98% 的置信水平下排除 Omega_0=1。虽然这种方法不需要遥远集群的明确定义的统计样本，但目前仍然存在建模不确定性，无法得出更确切的结论。
The evolution of the galaxy cluster abundance depends sensitively on the value of the cosmological density parameter, Omega_0. Recent ASCA data are used to quantify this evolution as measured by the X-ray temperature function. A chi^2 minimisation fit to the cumulative temperature function, as well as a maximum likelihood estimate (which requires additional assumptions about cluster luminosities), lead to the estimate Omega_0 \approx 0.45+/-0.2 (1-sigma statistical error). Various systematic uncertainties are considered, none of which enhance significantly the probability that Omega_0=1. These conclusions hold for models with or without a cosmological constant. The statistical uncertainties are at least as large as the individual systematic errors that have been considered here, suggesting that additional temperature measurements of distant clusters will allow an improvement in this estimate. An alternative method that uses the highest redshift clusters to place an upper limit on Omega_0 is also presented and tentatively applied, with the result that Omega_0=1 can be ruled out at the 98 per cent confidence level. Whilst this method does not require a well-defined statistical sample of distant clusters, there are still modelling uncertainties that preclude a firmer conclusion at this time.