Optical Identification of Galaxy Clusters among SRG/eROSITA X-ray Sources Based on Photometric Redshift Estimates for Galaxies

Abstract

We discuss an algorithm whereby the massive galaxy clusters detected in the SRG/eROSITA all-sky survey are identified and their photometric redshifts are estimated. For this purpose, we use photometric redshift estimates for galaxies and WISE forced photometry. To estimate the algorithm operation quality, we used a sample of 634 massive galaxy clusters from the Planck survey with known spectroscopic redshifts in the range $0.1<z_{spec}<0.6$. The accuracy of the photometric redshift estimates for this sample is $\delta z_{phot}/(1+z_{phot})\approx 0.5$%, the fraction of large deviations is 1.3%. We show that these large deviations arise mainly from the projections of galaxy clusters or other large-scale structures at different redshifts in the X-ray source field. Measuring the infrared (IR) luminosities of galaxy clusters allows one to estimate the reliability of the optical identification of the clusters detected in the SRG/eROSITA survey and to obtain an additional independent measurement of their total gravitational masses, $M_{500}$. We show that the masses $M_{500}$ of the galaxy clusters estimated from their IR luminosity measurements have an accuracy ${\sigma }_{\lg M_{500}}=0.124$, comparable to the accuracy of the mass estimation for the galaxy clusters from their X-ray luminosities.

References in corpus (8)

• The 400 square degrees ROSAT PSPC galaxy cluster survey: Catalog and statistical calibration
• The ART-XC telescope on board the SRG observatory
• The (im)possibility of strong chemical tagging
• Additional spectroscopic redshift measurements for galaxy clusters from the First Planck Catalogue
• Observation of a very massive galaxy cluster at z=0.76 in SRG/eROSITA all-sky survey
• Detailed Study of the Ursa Major Supercluster of Galaxies Using the 2MASS and SDSS Catalogs
• Direct illumination calibration of telescopes at the quantum precision limit
• New Active Galactic Nuclei Detected by the ART-XC and eROSITA Telescopes during the First Five SRG All-Sky X-ray Surveys

Cited by in corpus (1)

• Optical Identification and Spectroscopic Redshift Measurements of 216 Galaxy Clusters from the SRG/eROSITA All-Sky Survey