Exploring the dynamical nature and radio halo emission of Abell 384: a combined radio, X-ray, and optical study

Abstract

ABSTRACT Multiwavelength studies of galaxy clusters are crucial for understanding the complex interconnection of the thermal and non-thermal constituents of these massive structures and uncovering the physical processes involved in their formation and evolution. Here, we report a multiwavelength assessment of the galaxy cluster A384, which was previously reported to host a radio halo with a 660 kpc size at MeerKAT 1.28 GHz. The halo is slightly offset from the cluster centre. Our upgraded Giant Metrewave Radio Telescope observation reveals that the halo extends up to 690 kpc at 407 MHz with a non-uniform spectral index $\alpha ^{1284\ \mathrm{MHz}}_{407\ \mathrm{MHz}}$ distribution varying from flat (−0.5) to steep (−1.3) values. In addition, we use legacy GMRT 608 MHz, XMM–Newton X-ray, and the Dark Energy Survey optical observations to obtain an extensive understanding of the dynamical nature of the galaxy cluster. The X-ray surface brightness concentration parameter ($C_{\rm {SB}} = 0.16$) and centroid shift ($w = 0.057$) reveal an ongoing dynamical disturbance in the cluster. This is also supported by the elongated 2D optical galaxy density distribution map of the cluster. The obtained centre shift between optical and X-ray peaks and the asymmetry parameter from optical analysis further support the dynamical disturbance in the cluster. The radio and X-ray surface brightness follows a sublinear correlation. Our observations suggest that the cluster is currently in a merging state where particle re-acceleration in the turbulent intracluster medium resulted in the radio halo emission.