Constrain the three-dimensional separation of the high-redshift cluster pair 1eRASS-SC J0530-4138

Determine the three-dimensional separation between the galaxy clusters 1eRASS J052957.4-413822 and 1eRASS J053040.8-413904 that form the eRASS1 supercluster 1eRASS-SC J0530-4138 at redshift z≈0.802 by obtaining more precise redshifts, in order to assess their physical association and improve the reliability of this system.

Background

The most distant system identified in the catalog is a cluster pair at z≈0.802 with photometric redshifts that have relatively large uncertainties, preventing a precise determination of the true three-dimensional separation.

The authors report a projected separation of about 3.7 Mpc and a low reliability (P=0.50) for the association due to redshift uncertainties, indicating the need for improved redshift measurements (e.g., spectroscopy) to resolve the spatial relationship of the pair.

References

Due to the large error bar in redshifts, we are not able to precisely constrain the 3D distance between the two members. Therefore, this system has relatively low reliability, P=0.50.

— The SRG/eROSITA All-Sky Survey: First catalog of superclusters in the western Galactic hemisphere  (2402.08454 - Liu et al., 2024) in Section 4 (Properties of the eRASS1 superclusters), paragraph describing the most distant system; see Fig. 7 (Examples of supercluster systems)