The $10~\rm{kpc}$ collar of early-type galaxies -- probing evolution by focusing on the inner stellar density profile
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2025
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| _version_ | 1866915497682927616 |
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| author | Liu, Rongfu Sonnenfeld, Alessandro Nipoti, Carlo Li, Rui |
| author_facet | Liu, Rongfu Sonnenfeld, Alessandro Nipoti, Carlo Li, Rui |
| contents | 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 $10 ~\rm{kpc}$ from the galaxy center.
Methods: We first studied the stellar mass and mass-weighted density slope within $10 ~\rm{kpc}$, respectively $M_{*,10}$ and $\mathit{Γ_{*,10}}$, of a sample of early-type galaxies from the GAMA survey. We measured the $\mathit{Γ_{*,10}} - M_{*,10}$ relation and its evolution over the redshift range $0.17\leq z \leq 0.37$. 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 $\mathit{Γ_{*,10}} - M_{*,10}$ relation is consistent with a dry-merger evolution scenario.
Results: From the observations, we do not detect evidence for an evolution of the $\mathit{Γ_{*,10}} - M_{*,10}$ relation. We put an upper limit on the redshift derivative of the normalization$~(μ)$ and slope$~(β)$of the $\mathit{Γ_{*,10}} - M_{*,10}$ relation $|\partial μ/\partial \log (1+z)| \leq 0.13$ and $\left|\partial β/\partial \log (1+z)\right| \leq 1.10$, respectively. Simulations show that most mergers induce a decrease in $\mathit{Γ_{*,10}}$ 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 $f_M = 11.2 \%$ in the redshift range $0.17 \leq z \leq 0.37$.
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 $Δt \geq 3.2~\mathrm{Gyr}$, should enable us to detect a signal and help us better understand the late growth of ETGs. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_17413 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The $10~\rm{kpc}$ collar of early-type galaxies -- probing evolution by focusing on the inner stellar density profile Liu, Rongfu Sonnenfeld, Alessandro Nipoti, Carlo Li, Rui Astrophysics of Galaxies 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 $10 ~\rm{kpc}$ from the galaxy center. Methods: We first studied the stellar mass and mass-weighted density slope within $10 ~\rm{kpc}$, respectively $M_{*,10}$ and $\mathit{Γ_{*,10}}$, of a sample of early-type galaxies from the GAMA survey. We measured the $\mathit{Γ_{*,10}} - M_{*,10}$ relation and its evolution over the redshift range $0.17\leq z \leq 0.37$. 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 $\mathit{Γ_{*,10}} - M_{*,10}$ relation is consistent with a dry-merger evolution scenario. Results: From the observations, we do not detect evidence for an evolution of the $\mathit{Γ_{*,10}} - M_{*,10}$ relation. We put an upper limit on the redshift derivative of the normalization$~(μ)$ and slope$~(β)$of the $\mathit{Γ_{*,10}} - M_{*,10}$ relation $|\partial μ/\partial \log (1+z)| \leq 0.13$ and $\left|\partial β/\partial \log (1+z)\right| \leq 1.10$, respectively. Simulations show that most mergers induce a decrease in $\mathit{Γ_{*,10}}$ 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 $f_M = 11.2 \%$ in the redshift range $0.17 \leq z \leq 0.37$. 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 $Δt \geq 3.2~\mathrm{Gyr}$, should enable us to detect a signal and help us better understand the late growth of ETGs. |
| title | The $10~\rm{kpc}$ collar of early-type galaxies -- probing evolution by focusing on the inner stellar density profile |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2507.17413 |