Comparison of the halo from 144 MHz to 5.5 GHz. All images are at created at a common 8″ resolution. Top-middle panel: (111−182 MHz) adopted from Bonafede et al. (2018). The colors in all images were scaled manually. It is evident that the halo emission is more extended toward low frequencies. Contour levels are drawn at [1, 2, 4, 8, …] × 3.0σ_rms, where σ_{rms,  144 MHz} = 82 μJy beam⁻¹, σ_{rms,  147 MHz} = 130 μJy beam⁻¹, σ_{rms,  575 MHz} = 23 μJy beam⁻¹, σ_{rms,  1.5 GHz} = 7 μJy beam⁻¹, σ_{rms,  3.4 GHz} = 3 μJy beam⁻¹, and σ_{rms,  5.5 GHz} = 3.2 μJy beam⁻¹. The beam sizes are indicated in the bottom left corner of the each image.