https://vital.seals.ac.za/vital/access/manager/Index en-us 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:65374 Wed 10 Jan 2024 11:01:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:71937 Thu 04 Apr 2024 19:33:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:71936 6×1014 M⊙ at intermediate redshifts (0.3 < z < 0.4), providing support to their connection between mergers, which provide the necessary energy to re-accelerate particles via turbulence. Probing the redshift evolution of radio halos is an important test of the turbulent re-acceleration scenario, as fewer halos are expected at high redshift, given the same mass interval. In this thesis, we present MeerKAT observations at 1.28 GHz of three high-redshift (PSZ2G254.08- 58.45, PSZ2G255.60-46.18 and PSZ2G277.76-51.74, in the 0.42 ≲ z ≲ 0.46 range) clusters, with masses M500 ≳ 6.2 × 1014 M⊙, selected for their disturbed dynamical state – inferred from existing X-ray observations. Our observations reached rms noise values between 20 and 23.5 μJy beam−1, with ∼ 4′′ angular resolution. No evidence of diffuse emission is found at ii full resolution. Low-resolution (∼ 30′′) images achieved rms noise levels of 30-50 μJy beam−1, amongst the deepest observations of high-redshift targets. One radio halo was detected in the least massive cluster PSZ2G254.08-58.45 extending over ∼ 500 kpc, with a 1.20 } 0.08 mJy integrated flux density. We placed a ∼1 mJy upper limit at 95% confidence level on the radio halo flux density for the other two targets. The radio-halo detection is consistent with the recent P1.4 GHz − M500 correlation from Cuciti et al. (2021b), while the upper limit on PSZ2G255.60-46.18 is consistent with being on the correlation. On the other hand, the upper limit on PSZ2G277.76-51.74 places the radio halo well below the correlation. Recently a 1.5 GHz survey (Giovannini et al., 2020) detected a slightly higher fraction of radio halos in clusters in the same redshift range, with power and size typically higher than what we found in our observations. Both observations are, however, not inconsistent with each other. Our results, although with limited statistics, do not disfavour the current scenario of radiohalo formation based on the turbulent re-acceleration model.]]> Thu 04 Apr 2024 19:25:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:72181 Sun 21 Apr 2024 13:42:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:72878 Sun 02 Jun 2024 12:17:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:73152 Sat 08 Jun 2024 19:18:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:73151 Sat 08 Jun 2024 19:11:23 SAST ]]>