A MeerKAT-meets-LOFAR study of MS 1455.0 + 2232: a 590 kiloparsec ‘mini’-halo in a sloshing cool-core cluster

Radio mini-haloes are poorly-understood, moderately-extended diffuse radio sources that trace the presence of magnetic fields and relativistic electrons on scales hundreds kiloparsecs, predominantly in relaxed clusters. With relatively few confirmed detections to-date, many questions remain unanswered. This paper presents new observations galaxy cluster MS1455.0$+$2232 performed with MeerKAT (covering frequency range 872$-$1712 MHz) LOFAR 120$-$168 MHz), first results from a homogeneously selected mini-halo census. We find this extends for $\sim590$ kpc at 1283 MHz, significantly larger than previously believed, has flatter spectral index ($\alpha = -0.97 \pm 0.05$) typically expected. Our X-ray analysis clearly reveals large-scale (254 kpc) sloshing spiral intracluster medium. perform point-to-point analysis, finding tight single correlation between surface brightness super-linear slope $b_{\rm 1283~MHz} 1.16^{+0.06}_{-0.07}$ 145~MHz} 1.15^{+0.09}_{-0.08}$; indicates strong link thermal non-thermal components Conversely, index/X-ray plane, we regions inside outside follow different correlations. compelling evidence multiple sub-components time. While both turbulent (re-)acceleration hadronic scenarios able to explain some observed properties MS1455.0$+$2232, neither scenario is account all presented by our analysis.