Investigating dark energy by electromagnetic frequency shifts II: the Pantheon+ sample

Understand

Following results presented in Spallicci et al.

• (Eur Phys J Plus 137, 2022) by the same authors, we investigate the observed red shift $z$, working under the hypothesis that it might be composed by the expansion red shift $z_{\rm C}$ and an additional frequency shift $z_{\rm S}$, towards the red or the blue, due to Extended Theories of Electromagnetism (ETE).
• We have tested this prediction considering the novel Pantheon+ Catalogue, composed by 1701 light curves collected by 1550 SNe Ia, and 16 BAO data, for different cosmological models characterised by the absence of a dark energy component.
• In particular, we shall derive which values of $z_{\rm S}$ match the observations, comparing the new results with the ones obtained considering the older Pantheon Catalogue.