Issue |
A&A
Volume 693, January 2025
|
|
---|---|---|
Article Number | A282 | |
Number of page(s) | 16 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202452639 | |
Published online | 28 January 2025 |
Unveiling the formation channels of stellar halos through their chemical fingerprints
1
Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna, 4860 Santiago, Chile
2
Centro de AstroIngeniería, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna, 4860 Santiago, Chile
3
Núcleo Milenio ERIS, ANID, Chile
4
Departamento de Astronomía, Universidad de La Serena, Av. Raúl Bitrán, 1305 La Serena, Chile
5
Departamento de Física, Universidad Técnica Federico Santa María, Avenida España, 1680 Valparaíso, Chile
6
Instituto de Astronomía y Física del Espacio, CONICET-UBA, Casilla de Correos 67, Suc. 28, 1428 Buenos Aires, Argentina
⋆ Corresponding author; jagonzalez11@uc.cl
Received:
16
October
2024
Accepted:
21
November
2024
Context. Stellar halos around galaxies contain key information about their formation and assembly history. Using simulations, we can trace the origins of different stellar populations in these halos, contributing to our understanding of galaxy evolution.
Aims. We aim to investigate the assembly of stellar halos and their chemical abundances in 28 galaxies from CIELO cosmological hydrodynamical zoom-in simulations, spanning a broad range of stellar masses, M⋆,gal ∈ 109 − 1011 M⊙.
Methods. Stellar halos were identified using the AM-E method, focusing on the outer regions between the 1.5 optical radius and the virial radius. We divided the stellar populations based on their formation channel: ex-situ, endo-debris, and in-situ, and analyzed their chemical abundances, ages, and spatial distributions. Additionally, we explored correlations between halo mass, metallicity, and alpha-element enrichment.
Results. CIELO simulations reveal that stellar halos are predominantly composed of accreted material, including both ex-situ and endo-debris stars, in agreement with previous works. The mass fraction of these populations is independent of stellar halo mass, though their metallicities scale linearly with it. Ex-situ stars tend to dominate the outskirts and be more α-rich and older, while endo-debris stars are more prevalent at lower radii and tend to be less α-rich and slightly younger. Massive stellar halos (M⋆,halo > 109.5 M⊙ ) require a median of five additional satellites to build 90% of their mass, compared to lower-mass halos, which typically need fewer (median of 2.5) and lower-mass satellites and are assembled earlier. The diversity of accreted satellite histories results in well-defined stellar halo mass-metallicity and [α/Fe]-[Fe/H] relations, offering a detailed view of the chemical evolution and assembly history of stellar halos. We find that the [α/Fe]-[Fe/H] is more sensitive to the characteristics and star formation history of the contributing satellites than the stellar halo mass-metallicity relationship.
Key words: galaxies: abundances / galaxies: formation / galaxies: halos / galaxies: star formation
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.