Observation of a very massive galaxy cluster at z=0.76 in SRG/eROSITA all-sky survey

Abstract

The results of multiwavelength observations of the very massive galaxy cluster SRGe CL2305.2-2248 detected in X-rays during the first SRG/eROSITA all-sky survey are discussed. This galaxy cluster was also detected earlier in microwave band through the observations of Sunyaev-Zeldovich effect in South Pole Telescope (SPT-CL J2305-2248), and in Atacama Cosmological Telescope (ACT-CL J2305.1-2248) surveys. Spectroscopic redshift measurement, $z=0.7573$, was measured at the Russian 6-m BTA telescope of SAO RAS, in good agreement with its photometric estimates, including a very accurate one obtained using machine learning methods. In addition, deep photometric measurements were made at the Russian-Turkish 1.5-m telescope (RTT150), which allows to study cluster galaxies red sequence and projected galaxies distribution. Joint analysis of the data from X-ray and microwave observations show that this cluster can be identified as a very massive and distant one using the measurements of its X-ray flux and integral comptonization parameter only. The mass of the cluster estimated according to the eROSITA data is $M_{500}=(9.0\pm 2.6)\cdot 10^{14}{M}_{\odot }$. We show that this cluster is found among of only several dozen of the most massive clusters in the observable Universe and among of only a few the most massive clusters of galaxies at $z>0.6$.

10 pages, 6 figures, accepted for publication in Astronomy Letters

References in corpus (4)

• The eROSITA X-ray telescope on SRG
• The Atacama Cosmology Telescope: A Catalog of > 4000 Sunyaev-Zel'dovich Galaxy Clusters
• Deep Full-sky Coadds from Three Years of WISE and NEOWISE Observations
• (No) dimming of X-ray clusters beyond z~1 at fixed mass: crude redhshifts and masses from raw X-ray and SZ data

Cited by in corpus (5)

• Halo Scaling Relations and Hydrostatic Mass Bias in the Simba Simulation From Realistic Mock X-ray Catalogues
• Optical Identification and Spectroscopic Redshift Measurements of 216 Galaxy Clusters from the SRG/eROSITA All-Sky Survey
• Optical Identification of Galaxy Clusters among SRG/eROSITA X-ray Sources Based on Photometric Redshift Estimates for Galaxies
• X-ray flux -- mass relation for $z\gtrsim 0.7$ galaxy clusters
• Spectroscopic galaxy redshifts in the Peanut cluster -- a massive nearly head-on cluster merger shortly after pericenter passage