The cosmic radio dipole: Bayesian estimators on new and old radio surveys

Understand

The cosmic radio dipole is an anisotropy in the number counts of radio sources, analogous to the dipole seen in the cosmic microwave background (CMB).

• Measurements of source counts of large radio surveys have shown that though the radio dipole is generally consistent in direction with the CMB dipole, the amplitudes are in tension.
• These observations present an intriguing puzzle as to the cause of this discrepancy, with a true anisotropy breaking with the assumptions of the cosmological principle, invalidating the most common cosmological models that are built on these assumptions.
• We present a novel set of Bayesian estimators to determine the cosmic radio dipole and compare the results with commonly used methods on the Rapid ASKAP Continuum Survey (RACS) and the NRAO VLA Sky Survey (NVSS) radio surveys.