Accurate determination of H0 with core-collapse supernovae — adH0ccHYBRID

The discrepancy between early- and late-Universe measurements of the Hubble constant remains one of the central challenges in modern cosmology. I will present a distance-ladder–independent approach to determining the Hubble constant in the local universe based on the Expanding Photosphere Method (EPM) applied to Type II supernovae. EPM exploits the geometric relationship between the photospheric expansion velocity and the observed flux to infer distances directly from first principles, bypassing traditional calibrators such as Cepheids

I will discuss recent methodological advances, in particular tailored radiative-transfer modelling, aimed at improving the accuracy and systematic robustness of EPM-based distances. Particular emphasis will be placed on the role of dilution factors and systematic uncertainties associated with non-LTE effects and radiative transfer assumptions. I will show how this method enables competitive constraints on H0​ from low-redshift Type II supernovae and assess its potential as an independent probe in the context of the Hubble tension.

Vogl C., et al., 2025, A&A, 702, A41. doi:10.1051/0004-6361/202452910