Supermassive black holes in cosmological simulations I: MBH − M* relation and black hole mass function

Mélanie Habouzit, Yuan Li, Rachel S. Somerville, Shy Genel, Annalisa Pillepich, Marta Volonteri, Romeel Davé, Yetli Rosas-Guevara, Stuart McAlpine, Sébastien Peirani, Lars Hernquist, Daniel Anglés-Alcázar, Amy Reines, Richard Bower, Yohan Dubois, Dylan Nelson, Christophe Pichon, Mark Vogelsberger

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


The past decade has seen significant progress in understanding galaxy formation and evolution using large-scale cosmological simulations. While these simulations produce galaxies in overall good agreement with observations, they employ different sub-grid models for galaxies and supermassive black holes (BHs). We investigate the impact of the sub-grid models on the BH mass properties of the Illustris, TNG100, TNG300, Horizon-AGN, EAGLE, and SIMBA simulations, focusing on the MBH − M* relation and the BH mass function. All simulations predict tight MBH − M* relations, and struggle to produce BHs of MBH ≤ 107.5 M☉ in galaxies of M* ∼ 1010.5-1011.5 M☉. While the time evolution of the mean MBH − M* relation is mild (ΔMBH ≤ 1 dex for 0 ≤ z ≤ 5) for all the simulations, its linearity (shape) and normalization varies from simulation to simulation. The strength of SN feedback has a large impact on the linearity and time evolution for M* ≤ 1010.5 M☉. We find that the low-mass end is a good discriminant of the simulation models, and highlights the need for new observational constraints. At the high-mass end, strong AGN feedback can suppress the time evolution of the relation normalization. Compared with observations of the local Universe, we find an excess of BHs with MBH ≥ 109 M☉ in most of the simulations. The BH mass function is dominated by efficiently accreting BHs (log10 fEdd ≥ −2) at high redshifts, and transitions progressively from the high-mass to the low-mass end to be governed by inactive BHs. The transition time and the contribution of active BHs are different among the simulations, and can be used to evaluate models against observations.

Original languageEnglish (US)
Pages (from-to)1940-1975
Number of pages36
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - May 1 2021


  • Black hole physics
  • Galaxies: evolution
  • Galaxies: formation
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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