eROSITA and JWST; A Powerful Combination
SMACS J0723.3−7327 is the first galaxy cluster lens observed by James Webb Space Telescope (JWST). The eROSITA all-sky survey and Chandra, which provide high signal-to-noise ratio (S/N) and high angular resolution data, respectively, we were able to constrain the ICM gas density profile and temperature profile with good accuracy both in the core and to the outskirts. With the density and temperature profiles, we computed the hydrostatic mass profile, which was then projected along the line of sight to compare with the mass distribution obtained from the recent strong lensing analysis based on JWST data. We also deprojected the strong lensing mass distribution using the hydrostatic mass profile obtained in this work.
The X-ray results obtained from eROSITA and Chandra are in very good agreement. The hydrostatic mass profiles we measured in this work, both projected and deprojected, are in good agreement with recent strong lensing results based on JWST data, at all radii.
An Indepth Study of a Cluster Merger
In a work led by Sanders et al. (2022), we study a merging cluster Abell 3266, one of the brightest in the sky. Using the ability of the eROSITA to observe a wide field with a single pointing, we analysed a new deep eROSITA observations of the cluster out to the Virial radius. The eROSITA data confirm that the cluster is not a simple merging system, but it is made up of several subclusters which are merging or will shortly merge. With this pointing we detect several extended sources, where we find secure associations between z = 0.36-1.0 for seven of them, that is background galaxy groups and clusters, highlighting the power of eROSITA to find such systems. A press release about this work can be found here.