Investigating dark energy by electromagnetic frequency shifts

The observed red shift z might be composed by the expansion $$z_\mathrm{C}$$ and an additional frequency $$z_\mathrm{S}$$ , towards or blue, considering extended theories of electromagnetism (ETE). Indeed, massive photon theories—the has a real mass as in de Broglie–Proca theory effective standard-model extension, based on Lorentz–Poincaré symmetry violation (LSV)—or nonlinear may induce cosmological expansion-independent presence background (inter-) galactic electromagnetic fields, where relevance LSV even when both fields are constant. We have tested this prediction Pantheon Catalogue, 1048 SNe Ia, 15 BAO data, for different models characterised absence From we compute which values match observations, spanning parameters ( $$\Omega $$ densities Hubble–Lemaître constant) domains. conclude that can support alternative to accelerated expansion, naturally accommodating each SN Ia position distance modulus versus diagram, due light-path dependency . Finally, briefly mention laboratory test approaches investigate from ETE predictions.