Large-Scale Fluctuations in the Number Density of Galaxies in Independent Surveys of Deep Fields

TL;DR

This study provides evidence for large-scale fluctuations in galaxy density across deep fields, supporting the existence of structures up to 1000 Mpc, based on independent surveys and statistical correlation analysis.

Contribution

It demonstrates the reality of large-scale matter fluctuations using independent deep field surveys and correlation analysis, reducing the likelihood of systematic errors influencing results.

Findings

Positive correlation (R=0.70) supports real density fluctuations

Fluctuations up to 1000 Mpc in size and 20% in amplitude at z~2

No correlation between different fields confirms independence of structures

Abstract

New arguments supporting the reality of large-scale fluctuations in the density of the visible matter in deep galaxy surveys are presented. A statistical analysis of the radial distributions of galaxies in the COSMOS and HDF-N deep fields is presented. Independent spectral and photometric surveys exist for each field, carried out in different wavelength ranges and using different observing methods. Catalogs of photometric redshifts in the optical (COSMOS-Zphot) and infrared (UltraVISTA) were used for the COSMOS field in the redshift interval $0.1 < z < 3.5$, as well as the zCOSMOS (10kZ) spectroscopic survey and the XMM-COSMOS and ALHAMBRA-F4 photometric redshift surveys. The HDFN-Zphot and ALHAMBRA-F5 catalogs of photometric redshifts were used for the HDF-N field. The Pearson correlation coefficient for the fluctuations in the numbers of galaxies obtained for independent surveys of the same deep field reaches $R = 0.70 \pm 0.16$. The presence of this positive correlation supports the reality of fluctuations in the density of visible matter with sizes of up to 1 000 Mpc and amplitudes of up to 20% at redshifts $z \sim 2$. The absence of correlations between the fluctuations in different fields (the correlation coefficient between COSMOS and HDF-N is $R = -0.20 \pm 0.31$) testifies to the independence of structures visible in different directions on the celestial sphere. This also indicates an absence of any influence from universal systematic errors (such as "spectral voids"), which could imitate the detection of correlated structures.