2025/07/23 by Liu, Rongfu, Sonnenfeld, Alessandro, Nipoti, Carlo +1
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2507.17413
Aims: In this work we aim to investigate the late evolution of ETGs, both observationally and theoretically, by focusing on the stellar mass density profile inside a fixed aperture, within 10 ~\rmkpc from the galaxy center. Methods: We first studied the stellar mass and mass-weighted density slope within 10 ~\rmkpc, respectively M*,10 and \mathitΓ*,10, of a sample of early-type galaxies from the GAMA survey. We measured the \mathitΓ*,10 - M*,10 relation and its evolution over the redshift range 0.17≤ z ≤ 0.37. We then built a toy model for the merger evolution of galaxies, based on N-body simulations, to explore to what extent the observed growth in \mathitΓ*,10 - M*,10 relation is consistent with a dry-merger evolution scenario. Results: From the observations, we do not detect evidence for an evolution of the \mathitΓ*,10 - M*,10 relation. We put an upper limit on the redshift derivative of the normalization~(μ) and slope~(β)of the \mathitΓ*,10 - M*,10 relation |∂ μ/∂ log (1+z)| ≤ 0.13 and |∂ β/∂ log (1+z)| ≤ 1.10, respectively. Simulations show that most mergers induce a decrease in \mathitΓ*,10 and an increase in M*,10, although some show a decrease in M*,10, particularly for the most extended galaxies and smaller merger mass ratios. By combining the observations with our merger toy model, we placed an upper limit on fM = 11.2 % in the redshift range 0.17 ≤ z ≤ 0.37. Conclusions: While our measurement is limited by systematics, the application of our approach to samples with a larger redshift baseline, particularly with a time interval Δt ≥ 3.2~Gyr, should enable us to detect a signal and help us better understand the late growth of ETGs.