Abstract
New observations of high-redshift objects are crucial for the improvement of the standard ΛCDM cosmological model and our understanding of the Universe. One of the main directions of modern observational cosmology is the analysis of the large-scale structure of Universe, in particular, in deep fields. We study the large-scale structure of the Universe along the line of sight using the latest version of the COSMOS2015 catalogue, which contains 518,404 high quality photometric redshifts of galaxies selected in the optical range of the COSMOS field (2×2 deg2), with depth up to the redshift z∼6. We analyze large-scale fluctuations in the number of galaxies along the line of sight and provide an estimate of the average linear sizes of the self-correlating fluctuations (structures) in independent redshift bins of Δz=0.1 along with the estimate of the standard deviation from homogeneity (the observed cosmic variance). We suggest a new method of the line-of-sight analysis based on previous works and formulate further prospects of method development. For the case of the theoretical form of approximation of homogeneity in the ΛCDM framework, the average standard deviation of detected structures from homogeneity is σmeanΛCDM=0.09±0.02, and the average characteristic size of structures is RmeanΛCDM=790±150 Mpc. For the case of the empirical approximation of homogeneity, the average standard deviation of detected structures from homogeneity is σmeanempiric=0.08±0.01, and the average characteristic size of structures is Rmeanempiric=640±140 Mpc.
Highlights
The development of observational techniques and the increase of computing power at the beginning of the 21st century made it possible to study the evolution of large-scale structure of the Universe (LSSU) from the moment of birth of the first galaxies to the modern era
The ΛCDM model is the standard cosmological model (SCM) that assumes the homogeneous distribution of matter in the Universe (“at sufficiently large scales”) including cold dark matter and dark energy
We have considered the radial fluctuations of the number of galaxies along the line of sight in the photometric redshift space for the optical part of the COSMOS2015 catalog and some of its subsamples
Summary
The development of observational techniques and the increase of computing power at the beginning of the 21st century made it possible to study the evolution of large-scale structure of the Universe (LSSU) from the moment of birth of the first galaxies to the modern era. The ΛCDM model is the standard cosmological model (SCM) that assumes the homogeneous distribution of matter in the Universe (“at sufficiently large scales”) including cold dark matter and dark energy. The SCM implies the evolution of the density fluctuations of both dark and luminous matter with time, which is associated with the observed large-scale structure of the Universe. The SCM predicts that the primordial small density fluctuations of the dark and luminous matter. The largest predicted by ΛCDM structures have sizes about the scale of the Baryon
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