Extragalactic Radio Background

The extragalactic radio background (ERB) at frequencies below ~10 GHz exceeds the integrated flux from all known discrete radio source populations — radio galaxies, star-forming galaxies, and active galactic nuclei — by a factor of two to six depending on frequency. This excess, measured by ARCADE 2 and confirmed by long wavelength arrays, implies either a large population of faint, individually unresolved radio sources whose cumulative contribution has been underestimated, or a genuinely diffuse cosmological radio background from processes not included in standard ΛCDM models. Proposed ΛCDM explanations include very faint radio star-forming galaxies below current detection thresholds, radio emission from the intergalactic medium, or early universe processes, but none cleanly reproduces the observed spectral shape and amplitude across the full frequency range.

Successive Collision Theory provides a natural source for the excess extragalactic radio background through the pre-existing compact object and stellar populations from the colliding pockets. Magnetized neutron stars, pulsars, and magnetars from prior stellar generations in the two pockets contribute non-thermal synchrotron emission that is redshifted into the radio band from their formation epochs. Because these objects formed prior to the collision thermalization event, they contribute to the radio background from the earliest observable redshifts — well beyond the horizon of conventional radio surveys — with a spectrum shaped by synchrotron aging and redshift that naturally produces the excess radio power observed. The integrated contribution from these pre-existing radio-emitting populations over the full prior epoch available in eternal infinite spacetime can comfortably supply the observed ERB amplitude without invoking new sources.

The angular momentum inheritance mechanism ensures that the radio-emitting populations are clustered along the same large-scale structure traced by galaxies and the CMB, producing angular correlations in the ERB that should mirror the galaxy distribution at high redshift. SCT specifically predicts that the ERB should show a mild anisotropy correlated with the CMB quadrupole-octupole alignment axis — the collision axis — because the pre-existing radio sources that dominate the background were distributed along the angular momentum strata of the two colliding pockets, which defines the same preferred axis imprinted on the CMB. Cross-correlating ERB sky maps with large-scale structure tracers and the CMB polarization field provides a test of this prediction that distinguishes the SCT pre-existing-population explanation from purely diffuse intergalactic medium emission models.