2023/11/13 by Liang, Yan, Xu, Dandan, Sluse, Dominique +2 · 3 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2311.07442
A constant stellar mass-to-light ratio M_⋆/L has been widely-used in studies of galaxy dynamics and strong lensing, which aim at disentangling the mass distributions of dark matter and baryons. However, systematic biases arising from constant M_⋆/L assumption have not been fully quantified. In this work, we take massive early-type galaxies from the TNG100 simulation to investigate possible systematic biases in the inferences due to a constant M_⋆/L assumption. We construct two-component matter density models, where one component describes the dark matter, the other for the stars, which is made to follow the light profile by assuming a constant M_⋆/L. We fit the two-component model directly to the \it total matter density distributions of simulated galaxies to eliminate systematics coming from other model assumptions. We find that galaxies generally have more centrally-concentrated stellar mass profile than their light distribution. Given the light profiles adopted (i.e., single- and double-Sérsic profiles), the assumption of a constant M_⋆/L would artificially break the model degeneracy between baryons and dark matter \it for non-constant M_⋆/L systems. For such systems, without knowing the true M⋆/L but assuming a constant ratio, the two-component modeling procedure tend to generally overestimate M⋆/L by 30%-50%, and underestimate the central dark matter fraction f\rm DM by ∼ 20% on average.