Suzaku Observation of Merging Clusters Abell 222 and Abell 223

TL;DR

This study used Suzaku X-ray data to investigate a potential filamentary structure and warm-hot intergalactic medium connecting galaxy clusters Abell 222 and Abell 223, but results remain inconclusive due to uncertainties.

Contribution

The paper attempts to detect faint filamentary emission between clusters using Suzaku data, highlighting challenges in confirming such weak signals.

Findings

Unable to confirm the filamentary emission due to uncertainties

Careful contamination analysis was performed

Results do not definitively support the presence of WHIM

Abstract

Previous X-ray and optical studies of the galaxy cluster pair Abell 222/223 suggested the possible presence of a filamentary structure connecting the two clusters, a result that appears to be supported by subsequent weak-lensing analyses. This filament has been reported to host a primordial warm-hot intergalactic medium (WHIM), which existed prior to being heated by the interactions of the clusters. In this study, we made an attempt to examine the reported emission feature with data from an archival Suzaku observation, taking advantage of its low detector background. Because the emission is expected to be very weak, we first carefully examined all potential sources of "contamination", and then modelled the residual emission. Due to large uncertainties, unfortunately, our results can neither confirm the presence of the reported emission feature nor rule it out. We discuss the sources of uncertainties.