2021/10/15 by Gilbert Holder, Jens Chluba, Holder, Gilbert +1
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #astro-ph.CO
paper · pdf · doi:10.48550/arxiv.2110.08373
submitted to AAS Journals
arxiv created 2021/10/15 · arxiv updated 2021/10/19
If there is a substantial cosmological radio background, there should be a radio Sunyaev-Zeldovich (SZ) effect that goes along with it. The radio background Comptonization leads to a slight photon excess at all wavelengths, while Comptonization of the CMB at low frequencies leads to a decrement. For levels of the radio background consistent with observations, these effects cancel each other around ν≃ 735~MHz, with an excess at lower frequencies and a decrement at higher frequencies. Assuming a purely cosmological origin of the observed ARCADE radio excess, at ν\lesssim 20 \rm GHz the signal scales as ΔT / T\rm CMB≃ 2 y[ (ν/735 \rm MHz)-2.59-1] with frequency and the Compton-y parameter of the cluster. For a typical cluster, the total radio SZ signal is at the level of ΔT≃ 1 \rm mK around the null, with a steep scaling towards radio frequencies. This is above current raw sensitivity limits for many radio facilities at these wavelengths, providing a unique way to confirm the cosmological origin of the ARCADE excess and probe its properties (e.g., redshift dependence and isotropy). We also give an expression to compute the radio-analogue of the kinematic SZ effect, highlighting that this might provide a new tool to probe large-scale velocity fields and the cosmic evolution of the radio background.