2026/01/19 by K. S. L. Srikanth, A. Botteon, R. Cassano +20 · 1 voice
Physics and Astronomy · #astro-ph.CO
paper · pdf · doi:10.1051/0004-6361/202557927
Radio halos are megaparsec-scale diffuse, non-thermal radio sources located at the centers of galaxy clusters, tracing relativistic particles and magnetic fields in the intra-cluster medium. Their origin is generally attributed to cluster mergers that generate turbulence and re-accelerate aged electrons. We study the diffuse radio emission, spectral properties, and the connection between thermal and non-thermal components in the massive galaxy clusters Abell 773 and Abell 1351 (M500 ∼ 7 × 1014 M\odot), both of which are dynamically disturbed. We combine LOFAR LoTSS-DR2 observations at 144 MHz with uGMRT observations at 650 MHz, supplemented by archival XMM-Newton X-ray imaging. We confirm that both clusters host radio halos extending up to a largest linear size of ∼ 2 Mpc. We measure an integrated spectral index α144650 ∼ -1.0 for both clusters. The radio halo in Abell 773 resembles a classical halo and follows a sublinear radio--X-ray surface brightness relation. In contrast, Abell 1351 shows a more complex and asymmetric morphology, influenced by embedded radio sources including the brightest cluster galaxy, a tailed radio galaxy, and a ridge-like feature. These contaminating sources lead to deviations from the sublinear trend in the point-to-point radio--X-ray analysis of Abell 1351.