New galaxy cluster in the Zone of Avoidance SRGe CL0512.7+3712. Discovery and multi-wavelength characterization

The census of massive clusters of galaxies in the local Universe is almost complete, thanks to their prominent observational signatures at X-ray, optical, and sub-mm wavelengths. Nevertheless, a number of such systems are likely to be missing and hidden behind the plane of our Galaxy, where high interstellar absorption as well as strong contamination by foreground stellar and diffuse sources prevent detection of even the brightest and the most massive ones. Here we report the discovery and multiwavelength characterization of such a cluster in the zone of avoidance (ZoA) SRGe CL0512.7+3712 in the data of SRG/eROSITA all-sky survey. Combining the data of radio, optical, and infrared surveys, we identify overdensity of possible red sequence galaxies, as well as the candidate brightest cluster galaxy. Follow-up optical and X-ray observations confirm that the newly found object is a massive ($M_{500c}=(4-5)\cdot 10^{14}M_{\odot}$, $kT\approx 5 $ keV) galaxy cluster at redshift $z=0.0745$ with possible indications of unrelaxed dynamical scale. Location and elongation of this cluster is consistent with an expectation from the large-scale structure at this redshift, and it might be a part of an extended overdensity of such objects in the Galactic Anticenter direction. Examination of X-ray, radio, and infrared data in the locations of ZoA, where similar objects are expected to be found based on the large-scale structure properties, might reveal another $\sim10$ clusters at this redshift in future.