Radio ghosts: Radio polarimetry study of newly discovered cluster minihalo candidates or radio tailed galaxies
Abstract
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, MKTJ0355-4237 and MKTJ0355-4230, to assess their nature and investigate their radio spectral and magnetic field properties through radio polarimetric analysis. We use 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. These are complemented by eROSITA X-ray data and DESI photometric redshift catalogues to characterise the host cluster environments. MKTJ0355-4237 is confirmed as cluster-scale minihalo with extent of ∼ 400 kpc, while the other diffuse source MKTJ0355-4230 remain uncertain and could be either associated with a radio minihalo or radio tailed galaxy. Both show steep spectra (α≈ −0.7 to −0.8) that steepen toward the outskirts (α≲ −2.5), consistent with spatial variations in electron ageing and re-acceleration. Polarised emission is detected in both systems, with fractional polarisation ∼1 % in the centres and increasing in the outer regions of MKTJ0355-4237. MKTJ0355-4230 is associated with a previously uncatalogued cluster and shows an X-ray morphology offset from the brightest cluster galaxy, indicative of dynamical activity. MKTJ0355-4237 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.
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BibTeX
@misc{taziaux2026radio,
title = {{Radio ghosts: Radio polarimetry study of newly discovered cluster minihalo candidates or radio tailed galaxies}},
author = {Sam Taziaux and Christopher J. Riseley and Stefan W. Duchesne and Francesca Loi and Alec J. M. Thomson and Aritra Basu and Timothy J. Galvin and Dominik J. Bomans},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18099},
eprint = {2610.18099},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.18099},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Radio ghosts: Radio polarimetry study of newly discovered cluster minihalo candidates or radio tailed galaxies
AU - Sam Taziaux
AU - Christopher J. Riseley
AU - Stefan W. Duchesne
AU - Francesca Loi
AU - Alec J. M. Thomson
AU - Aritra Basu
AU - Timothy J. Galvin
AU - Dominik J. Bomans
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.18099
UR - https://arxiv.org/abs/2610.18099
AB - 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, MKTJ0355-4237 and MKTJ0355-4230, to assess their nature and investigate their radio spectral and magnetic field properties through radio polarimetric analysis. We use 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. These are complemented by eROSITA X-ray data and DESI photometric redshift catalogues to characterise the host cluster environments. MKTJ0355-4237 is confirmed as cluster-scale minihalo with extent of ∼ 400 kpc, while the other diffuse source MKTJ0355-4230 remain uncertain and could be either associated with a radio minihalo or radio tailed galaxy. Both show steep spectra (α≈ −0.7 to −0.8) that steepen toward the outskirts (α≲ −2.5), consistent with spatial variations in electron ageing and re-acceleration. Polarised emission is detected in both systems, with fractional polarisation ∼1 % in the centres and increasing in the outer regions of MKTJ0355-4237. MKTJ0355-4230 is associated with a previously uncatalogued cluster and shows an X-ray morphology offset from the brightest cluster galaxy, indicative of dynamical activity. MKTJ0355-4237 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.
ER -