ABSTRACT We examine the impact of progenitor age-dependent luminosity evolution of Type Ia supernovae on a cosmographic measurement of the deceleration parameter q₀. Our recent redshift tomographic analysis showed that locally q₀ has a strong dipole anisotropy aligned approximately with the bulk flow, and only a small monopole component remains at distances exceeding a few hundred Mpc. Applying redshift-dependent corrections for progenitor age to the Pantheon + catalogue, we find that this shifts the monopole component of q₀ to positive values (i. e. deceleration) while leaving the local dipole component essentially unchanged.
Sah et al. (2026) studied this question.