Search for the Most Massive Galaxy Clusters at High Redshifts Based on Sky Surveys in the Sub-mm, Optical and X-ray Ranges

Galaxy clusters are the largest gravitationally bound systems in the universe. They form the largest-scale structure in the universe and play a crucial role in understanding the formation and evolution of galaxies. The most interesting and important clusters are those that are massive and located at great distances. These unique objects are essential for creating cosmological samples and studying the evolution of the universe. Our research aimed to identify and study massive X-ray galaxy clusters at high redshifts using a combination of observational data from three ranges: X-ray, optical, and submillimeter data. We used the DECaLS optical survey to measure redshift, the eROSITA X-ray telescope and the submillimeter data to estimate mass of galaxy cluster (M500c). As a result, 18 candidates for X-ray clusters of galaxies with masses from 3 × 10^14 M_sun to 7 × 10^14 M_sun were found at redshifts greater than 1. The most distant object was located at z=1.416. Clusters with quasars in the center and a merging cluster were also identified among these objects. The method of measuring the photometric redshift is based on spectral patterns. It has been possible to reduce the measurement error to 2.2×10^(-2) for high z. The resulting catalog contains unique clusters of galaxies at high redshifts of interest to scientists. The method of optical cluster identification and photometric redshift measurement was used to analyze the ComPACT catalog, 239 galaxy clusters were identified, and their photometric redshifts were measured.