Radio ghosts: Radio polarimetry study of newly discovered cluster minihalo candidates or radio tailed galaxies

Extended diffuse radio emission in the central regions of galaxy clusters is commonly associated with non-thermal processes in the intracluster medium (ICM), but its origin and the mechanisms responsible for sustaining it remain uncertain. We present the discovery and multi-wavelength analysis of two diffuse radio sources, MKT,J0355--4237 and MKT,J0355--4230, to assess their nature and investigate their radio spectral and magnetic field properties through radio polarimetric analysis. We used deep MeerKAT L band (1.28,GHz) observations to perform spectral analysis of the diffuse emission and study its polarisation properties via rotation measure synthesis. We complement these observations with eROSITA X-ray data and DESI photometric redshift catalogues to characterise the host cluster environments. We confirm MKT,J0355--4237 as a cluster-scale minihalo with an extent of ∼ 400,kpc, while the nature of the other diffuse source, MKT,J0355--4230, remains uncertain; it could be associated with either a radio minihalo or a radio tailed galaxy. Both sources show steep spectra (α ≈ -0.7 to -0.8) that steepen towards the outskirts (α łesssim -2.5), consistent with spatial variations in electron ageing and re-acceleration. We detect polarised emission in both systems, with a fractional polarisation of sim1,% in the centres and an increase in the outer regions of MKT,J0355--4237. MKT,J0355--4230 is associated with a previously uncatalogued cluster and shows an X-ray morphology offset from the brightest cluster galaxy, indicative of dynamical activity. MKT,J0355--4237 exhibits a sharply bounded internal radio deficit without a corresponding X-ray counterpart, within current sensitivity limits. The spectral steepening supports turbulent re-acceleration as the origin of the diffuse emission. The detection of polarisation indicates partially ordered magnetic fields in the ICM. The internal radio deficit may trace local variations in particle re-acceleration or fossil active galactic nucleus (AGN) plasma embedded within the minihalo.