Work

Photometric versus dynamical stellar masses and their impact on scaling relations in nearby disc galaxies

Year: 2025

Type: article

Abstract: 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 (Mphot) 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 (Mdyn), available for nearby galaxies. Here, we compare newly determined, SED-model-based Mphot with previously obtained Mdyn 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 Mphot 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 Mdyn or Mphot 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.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202553925

Authors: A. Marasco, S. M. Fall, E. M. Di Teodoro, P. E. Mancera Piña