Determine whether the intracluster medium is dissociated from the outer subclusters

Determine whether the intracluster medium of 1eRASS J025859.4-193727 is truly dissociated from subclusters B and C through deeper X-ray imaging, in order to test the proposed dissociative-merger interpretation of the shallow eROSITA morphology.

Background

The spectroscopic and projected-density analyses identify three subclusters in 1eRASS J025859.4-193727. The central subcluster A is associated with the main X-ray emission, whereas subcluster B overlaps mainly with the edges of the X-ray emission and subcluster C has no apparent associated X-ray emission. This spatial offset between the galaxy substructures and the collisional intracluster gas may indicate a dissociative merger.

The authors caution that the conclusion is limited by the shallow eROSITA exposure, whose average exposure time for the cluster is approximately 199 seconds. Deeper X-ray observations are therefore needed to establish whether the apparent absence of gas around subclusters B and C is physical or instead reflects insufficient sensitivity.

References

We call for further investigations to better constrain the nature of J025859. For example, deeper X--ray imaging will reveal whether or not the ICM is truly dissociated from subclusters B and C as suggested by our shallow eROSITA contours (see Fig. \ref{fig:mclust_groups}).

— The extreme Disturbed Galaxy Cluster Sample (eDGeS): Spectroscopy and Dynamical Analysis of the eROSITA-Selected Merging Galaxy Cluster Candidate 1eRASS J025859.4-193727  (2609.19509 - Aradhey et al., 16 Sep 2026) in Section 4, Conclusions (following the numbered summary); see also Section 5.1, X-ray Morphology