Speaker
Description
The radial acceleration relation (RAR) is a fundamental relation linking baryonic and dark matter in disc galaxies through the observed acceleration derived from dynamics to the one estimated from the baryonic mass. Notably, this relation exhibits small scatter, thus providing key constraints for models of galaxy formation and evolution, by essentially allowing us to map the distribution of dark matter in galaxies. However, it has only been extensively studied in the very local Universe.
In this talk, I present new measurements of the RAR, utilising a homogeneous, unbiased sample of HI-selected galaxies from the MeerKAT International Tiered Extragalactic Exploration (MIGHTEE) survey.
I introduce a novel approach of resolved stellar mass modelling from spectral energy distribution (SED) fitting across 10 photometric bands to determine the resolved mass-to-light ratio, which is essential for measuring the baryonic acceleration, as opposed to relying on a fixed mass-to-light ratio.
Our findings show that the stellar mass-to-light ratio varies across galaxies and radially. The results suggest that the RAR in this sample favours lower mass-to-light ratios compared to previous studies. I find that adopting a spatially varying mass-to-light ratio yields the tightest RAR with an intrinsic scatter of only 0.04 ± 0.02 dex.
I will address the implications of these findings for the fundamental nature of RAR. The results highlight the importance of resolved stellar mass measurements in accurately characterising the baryonic contribution to the rotation curve and in providing constraints to break the disk-halo degeneracy, opening exciting prospects in future studies with upcoming HI surveys.
