Intensity Fluctuations of Radio Halos in Galaxy Clusters: Insights from Power Spectrum Estimation

Nonthermal synchrotron emissions from radio halos allow us to study mechanisms of particle (re)acceleration, magnetic field distribution, merger history, and turbulence in the intracluster medium. We propose power spectrum estimation as a novel and complementary method to study galaxy clusters. We use 610 MHz observations of MACS J0014.3–302 and MACS J0152.5–2852 to estimate the angular power spectrum ( C ℓ ) from the central halo regions. The C ℓ shows excess emission only for MACS J0014.3–302. Using simulations, we find that a halo model with power-law fluctuations, in addition to the smooth exponential radial profile, is required to explain the observed C ℓ . We compare the observed power law with existing models of MHD turbulence. The method may be useful for large data from SKA, finding megahalos in other sources, or detecting faint cluster emissions beyond the visible extent.