The $10 kpc $ collar of early-type galaxies: Probing evolution by focusing on the inner stellar density profile

The post-quenching evolution process of early-type galaxies (ETGs), which is typically driven by mergers, is still not fully understood. The amount of growth in stellar mass and size incurred after quenching is still under debate. In this work, we investigated the late evolution of ETGs, both observationally and theoretically, by focusing on the stellar mass density profile inside a fixed aperture, within $10$ kpc from the galaxy center. We first studied the stellar mass and the mass-weighted density slope within $10 kpc $, respectively M_*,10 and mathit Γ_ of a sample of ETGs from the GAMA survey. We measured the and its evolution over the redshift range $0.17łeq z łeq 0.37$. 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 is consistent with a dry-merger evolution scenario. From the observations, we do not detect evidence for an evolution of the relation. We put an upper limit on the redshift derivative of the normalization$ (μ)$ and slope$ (β)$ of the $|∂ μ/∂ łog (1+z)| łeq 0.13$ and łeft|∂ β/∂ łog (1+z)̊ight| łeq 1.10, respectively. Simulations show that most mergers induce a decrease in mathit Γ_ 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 place an upper limit on the fractional stellar mass growth of f_M = 11.2 % in the redshift range $0.17 łeq z łeq 0.37$. While our measurement is limited by systematics, the application of our approach to samples with a larger redshift baseline, particularly with a time interval Δ t ≥ 3.2 Gyr should enable detection of a signal and improves our understanding of the late growth of ETGs.