Mass Proxy Quality of Halo Properties in IllustrisTNG and FLAMINGO Simulations: II. Galaxies, Stars, and Black Holes

@misc{aljamal2026mass,
  title = {{Mass Proxy Quality of Halo Properties in IllustrisTNG and FLAMINGO Simulations: II. Galaxies, Stars, and Black Holes}},
  author = {Eddie Aljamal and August E. Evrard and Arya Farahi and Dylan Nelson},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.10901},
  eprint = {2610.10901},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.10901},
}

TY  - UNPB
TI  - Mass Proxy Quality of Halo Properties in IllustrisTNG and FLAMINGO Simulations: II. Galaxies, Stars, and Black Holes
AU  - Eddie Aljamal
AU  - August E. Evrard
AU  - Arya Farahi
AU  - Dylan Nelson
PY  - 2026
DA  - 2026/10/09
PB  - arXiv
DO  - 10.48550/arxiv.2610.10901
UR  - https://arxiv.org/abs/2610.10901
AB  - We study the stellar, black hole, and satellite galaxy populations of group- and cluster-scale halos in the IllustrisTNG, TNG-Cluster, and FLAMINGO cosmological hydrodynamical simulations. We characterize the mass-conditioned scaling relations, covariance, conditional likelihoods, and mass proxy quality (MPQ) of integral properties within R_500c: total stellar mass (M_⋆, tot), brightest central galaxy stellar mass (M_⋆, BCG), intracluster light mass (M_⋆, ICL), total black hole mass (M_BH), satellite occupation (N_sat), and satellite velocity dispersion (σ_sat, 1D), at z∈ {0,0.5,1,2}. While normalization differences of up to a factor of two emerge among simulations, many properties exhibit remarkably similar mass-localized slopes, intrinsic scatters, and MPQs across halo samples and redshifts. Correlations among stellar, satellite, and gas properties are generally consistent in sign and their dependence on halo mass and redshift, whereas those involving M_BH and N_sat show greater variation, particularly in TNG-Cluster. Conditional likelihoods are nearly lognormal for many properties, including M_⋆, tot, N_sat, and σ_sat, 1D, while M_⋆, BCG and M_⋆, ICL are negatively skewed. Among the properties considered here, total stellar mass is the best mass proxy, with a halo mass scatter of $7−14\%$, followed by N_sat with a mass scatter of $9−18\%$. The consistent correlation behavior of M_⋆, ICL highlights its potential for next-generation observational studies. Finally, σ_sat, 1D exhibits highly consistent scaling, with mass-independent slope and scatter and a largely neutral correlation structure, suggesting that it is relatively insensitive to astrophysical complexity.
ER  -