Abell 746: A Highly Disturbed Cluster Undergoing Multiple Mergers

Rajpurohit, K. ; Lovisari, L. ; Botteon, A. ; Jones, C. ; Forman, W. ; O'Sullivan, E. ; van Weeren, R. J. ; HyeongHan, K. ; Bonafede, A. ; Jee, M. J. ; Vazza, F. ; Brunetti, G. ; Cho, H. ; Domínguez-Fernández, P. ; Stroe, A. ; Finner, K. ; Brüggen, M. ; Vrtilek, J. M. ; David, L. P. ; Schellenberger, G. ; Wittman, D. ; Lusetti, G. ; Kraft, R. ; De Gasperin, F.

We present deep XMM-Newton, Karl G. Jansky Very Large Array, and upgraded Giant Metrewave Radio Telescope observations of Abell 746, a cluster that hosts a plethora of diffuse emission sources that provide evidence for the acceleration of relativistic particles. Our new XMM-Newton images reveal a complex morphology of the thermal gas with several substructures. We observe an asymmetric temperature distribution across the cluster: the southern regions exhibit higher temperatures, reaching ∼9 keV, while the northern regions have lower temperatures (≤4 keV), likely due to a complex merger. We find evidence of three surface brightness edges and one candidate edge, of which three are merger-driven shock fronts. Combining our new data with published LOw-Frequency ARray observations has unveiled the nature of diffuse sources in this system. The bright NW relic shows thin filaments and a high degree of polarization with aligned magnetic field vectors. We detect a density jump, aligned with the fainter relic to the north. To the south, we detect high-temperature regions, consistent with the shock-heated regions and a density jump coincident with the northern tip of the southern radio structure. Its integrated spectrum shows a high-frequency steepening. Lastly, we find that the cluster hosts large-scale radio halo emission. A comparison of the thermal and nonthermal emission reveals an anticorrelation between the bright radio and X-ray features at the center. Our findings suggest that Abell 746 is a complex system that involves multiple mergers.

https://ui.adsabs.harvard.edu/abs/2024ApJ...966...38R/abstract