作为分形系统的星系分布
Galaxy Distributions as Fractal Systems
摘要：
本文讨论了包含近百万个天体的大尺度星系分布样本是否可以表征为分形系统。Teles等人（2021; arXiv：2012.07164）对UltraVISTA DR 1巡天进行的分析在这里扩展到SPLASH和COSMOS 2015星表，因此在研究样本中增加了750 k个新星系，并测量了红移。标准的$Λ$ CDM宇宙学具有$H_0=(70\pm5)$ km/s/Mpc和数密度工具，用于将这些星系分布描述为具有维度$D$的单个分形系统。我们使用光度距离$d_L$，红移距离$d_z$和星系面积距离（横向共动距离）$d_G$作为相对论距离的定义，推导出星系数密度的红移间隔$0.1\le z\le4$在体积有限的子样本定义的绝对星等在K波段。与Teles等人（2021; arXiv：2012.07164）的发现类似，结果显示了两个连续的红移尺度，其中星系分布数据表现为单一的分形结构。对于$z<1$，我们发现SPLASH星系有$D=1.00\pm0.12$，COSMOS 2015有$D=1,39\pm0.19$。对于$1\le z\le4$，我们分别发现了$D=0.83^{+0.36}_{-0.37}$和$D=0.54^{+0.27}_{-0.26}$。这些结果被证实是稳健的假设哈勃常数的不确定性。在两次调查中考虑蓝色和红色星系子样本的计算表明，蓝色星系的分形维数基本上没有变化，但红色星系的分形维数主要变化到较小的值，这意味着PDMATHAMO可能被视为宇宙中物体分布的一个更内在的属性，因此允许分形维数被用作研究不同星系群的工具。所有结果证实了几十年前的理论预测$z>1$的分形维数的减少。
英文摘要：
This paper discusses if large scale galaxy distribution samples containing almost one million objects can be characterized as fractal systems. The analysis performed by Teles et al. (2021; arXiv:2012.07164) on the UltraVISTA DR1 survey is extended here to the SPLASH and COSMOS2015 catalogs, hence adding 750k new galaxies with measured redshifts to the studied samples. The standard $Λ$CDM cosmology having $H_0=(70\pm5)$ km/s/Mpc and number density tools required for describing these galaxy distributions as single fractal systems with dimension $D$ are adopted. We use the luminosity distance $d_L$, redshift distance $d_z$ and galaxy area distance (transverse comoving distance) $d_G$ as relativistic distance definitions to derive galaxy number densities in the redshift interval $0.1\le z\le4$ at volume limited subsamples defined by absolute magnitudes in the K-band. Similar to the findings of Teles et al. (2021; arXiv:2012.07164), the results show two consecutive redshift scales where galaxy distribution data behave as single fractal structures. For $z<1$ we found $D=1.00\pm0.12$ for the SPLASH galaxies, and $D=1,39\pm0.19$ for the COSMOS2015. For $1\le z\le4$ we respectively found $D=0.83^{+0.36}_{-0.37}$ and $D=0.54^{+0.27}_{-0.26}$. These results were verified to be robust under the assumed Hubble constant uncertainty. Calculations considering blue and red galaxies subsamples in both surveys showed that the fractal dimensions of blue galaxies as basically unchanged, but the ones for the red galaxies changed mostly to smaller values, meaning that $D$ may be seen as a more intrinsic property of the distribution of objects in the Universe, therefore allowing for the fractal dimension to be used as a tool to study different populations of galaxies. All results confirm the decades old theoretical prediction of a decrease in the fractal dimension for $z>1$.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
