TY - JOUR
T1 - Constraints on the in situ and ex situ stellar masses in nearby galaxies obtained with artificial intelligence
AU - Angeloudi, Eirini
AU - Falcón-Barroso, Jesús
AU - Huertas-Company, Marc
AU - Boecker, Alina
AU - Sarmiento, Regina
AU - Eisert, Lukas
AU - Pillepich, Annalisa
N1 - Publisher Copyright:
© The Author(s), under exclusive licence to Springer Nature Limited 2024.
PY - 2024/10
Y1 - 2024/10
N2 - The hierarchical model of galaxy evolution suggests that mergers have a substantial impact on the intricate processes that drive stellar assembly within a galaxy. However, accurately measuring the contribution of accretion to a galaxy’s total stellar mass and its balance with in situ star formation poses a persistent challenge, as it is neither directly observable nor easily inferred from observational properties. Using data from MaNGA, we present theory-motivated predictions for the fraction of stellar mass originating from mergers in a statistically significant sample of nearby galaxies. Employing a robust machine learning model trained on mock MaNGA analogues (MaNGIA) obtained from a cosmological simulation (TNG50), we unveil that in situ stellar mass dominates almost across the entire stellar mass spectrum (109 M⊙ < M⋆ < 1012 M⊙). Only in more massive galaxies (M⋆ > 1011 M⊙) does accreted mass become a substantial contributor, reaching up to 35–40% of the total stellar mass. Notably, the ex situ stellar mass in the nearby Universe exhibits notable dependence on galaxy characteristics, with higher accreted fractions favoured being by elliptical, quenched galaxies and slow rotators, as well as galaxies at the centre of more massive dark matter haloes.
AB - The hierarchical model of galaxy evolution suggests that mergers have a substantial impact on the intricate processes that drive stellar assembly within a galaxy. However, accurately measuring the contribution of accretion to a galaxy’s total stellar mass and its balance with in situ star formation poses a persistent challenge, as it is neither directly observable nor easily inferred from observational properties. Using data from MaNGA, we present theory-motivated predictions for the fraction of stellar mass originating from mergers in a statistically significant sample of nearby galaxies. Employing a robust machine learning model trained on mock MaNGA analogues (MaNGIA) obtained from a cosmological simulation (TNG50), we unveil that in situ stellar mass dominates almost across the entire stellar mass spectrum (109 M⊙ < M⋆ < 1012 M⊙). Only in more massive galaxies (M⋆ > 1011 M⊙) does accreted mass become a substantial contributor, reaching up to 35–40% of the total stellar mass. Notably, the ex situ stellar mass in the nearby Universe exhibits notable dependence on galaxy characteristics, with higher accreted fractions favoured being by elliptical, quenched galaxies and slow rotators, as well as galaxies at the centre of more massive dark matter haloes.
UR - http://www.scopus.com/inward/record.url?scp=85199140482&partnerID=8YFLogxK
U2 - 10.1038/s41550-024-02327-3
DO - 10.1038/s41550-024-02327-3
M3 - Article
AN - SCOPUS:85199140482
SN - 2397-3366
VL - 8
SP - 1310
EP - 1320
JO - Nature Astronomy
JF - Nature Astronomy
IS - 10
ER -