arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0905.4361astro-ph.CO
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K波段选择本星系的成团

Clustering of K-band selected local galaxies

Bin Ma, Kelai Meng, Jun Pan, Jiasheng Huang, Longlong Feng

摘要:

我们提出了详细的聚类分析的一个大的K波段选择的本地星系样本,这是由2MASS和SDSS构建的$82,486$星系与$10 < K < 13.5$和$0.01 < z < 0.1$。在小尺度下,实空间中限幅样本的两点关联函数可用幂律$ξ(r)=(r/6.44\pm0.23)^{-1.81\pm0.02}$来描述。由各向异性两点关联函数导出了两两速度色散,并在尺度不变性的条件下求出了色散$σ_{12}=685\pm 17\kms$,该色散大于在光学波段所选星系样本中测得的色散值。我们进一步研究了两点关联函数和$σ_{12}$对$g-r$颜色和$K$波段亮度的依赖关系,得到了与光学波段类似的结果。模拟星系样本与真实数据的比较表明,半解析模型虽然能在测量不确定度范围内近似两点关联函数,但不能模拟观测中的$σ_{12}$.

英文摘要:

We present detailed clustering analysis of a large K-band selected local galaxy sample, which is constructed from the 2MASS and the SDSS and consists of $82,486$ galaxies with $10 < K < 13.5$ and $0.01 < z < 0.1$. The two-point correlation function of the magnitude-limited sample in real space at small scales is well described by a power law $ξ(r)=(r/6.44\pm0.23)^{-1.81\pm0.02}$. The pairwise velocity dispersion is derived from the anisotropic two-point correlation function and find the dispersion $σ_{12}=685\pm 17\kms$ if its scale invariance is assumed, which is larger than values measured in optical bands selected galaxy samples. We further investigate the dependence of the two-point correlation function and the $σ_{12}$ on the $g-r$ color and the $K$-band luminosity, obtain similar results to previous works in optical bands. Comparing a mock galaxy sample with our real data indicates that the semi-analytical model can not mimic the $σ_{12}$ in observation albeit it can approximate the two-point correlation function within measurement uncertainties.

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