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

• Main Authors: Burenin, R. A., Bikmaev, I. F., Gilfanov, M. R., Grokhovskaya, A. A., Dodonov, S. N., Eselevich, M. V., Zaznobin, I. A., Irtuganov, E. N., Lyskova, N. S., Medvedev, P. S., Meshcheryakov, A. V., Moiseev, A. V., Sazonov, S. Yu., Starobinsky, A. A., Sunyaev, R. A., Uklein, R. I., Khabibullin, I. I., Khamitov, I. M., Churazov, E. M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2021
• Subjects: Cosmology and Nongalactic Astrophysics astro-ph.CO; FOS Physical sciences; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.2108.09252; https://arxiv.org/abs/2108.09252

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 $M_{500}=(9.0\pm2.6)\cdot10^{14}\, M_\odot$. 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