2025A&A...695L..23M

The study of scaling relations of disc galaxies and their evolution across cosmic time requires accurate estimates of galaxy stellar masses, M_⋆, over broad redshift ranges. While photometric M_⋆ estimates (M_phot) based on spectral energy distribution (SED) modelling methods are employed routinely at high-z, it is unclear to what extent these are compatible with dynamical M_⋆ estimates (M_dyn), available for nearby galaxies. Here, we compare newly determined, SED-model-based M_phot with previously obtained M_dyn inferred via rotation curve decomposition techniques in a sample of ∼100 nearby galaxies from the SPARC database. We find that the two mass estimates show a systematic agreement at the ∼12% (0.05 dex) level and a ∼55% (0.22 dex) scatter across almost 5 dex in M_⋆. Our M_phot estimates correspond to mass-to-light ratios in the 3.6 μm band that increase gradually with 3.6 μm luminosity, as a consequence of the earlier (later) assembly history of high-mass (low-mass) disc galaxies. The choice of using either M_dyn or M_phot has only a marginal impact on the slope and zero-point of the Tully-Fisher and Fall relations: the observed orthogonal scatter in both relations is virtually the same for the two methods, and indistinguishable from that derived using a constant mass-to-light ratio in the 3.6 μm band. M_⋆ estimates based on the assumption that discs are marginally stable lead to the largest scatter in the scaling relations.