English

The Baryonic Mass-Halo Mass Relation of Extragalactic Systems

Astrophysics of Galaxies 2026-03-09 v1 Cosmology and Nongalactic Astrophysics

Abstract

We combine data for extragalactic systems to quantify a relation between the observed baryonic mass MbM_b and the enclosed dynamical mass M200M_{200} inferred from kinematics or gravitational lensing. Our sample covers nine orders of magnitude in baryonic mass, including galaxies with kinematic or weak gravitational lensing data and groups and clusters of galaxies with new gravitational lensing data. For rich clusters with Mb>1014  MM_b > 10^{14}\;\mathrm{M}_{\odot}, the observed baryon fraction is consistent with the cosmic value, fb=0.157f_b = 0.157. For lower masses, the baryon fraction decreases systematically with mass. The variation is well described by Mb/M200=fbtanh(Mb/M0)1/4M_b/M_{200} = f_b \tanh(M_b/M_0)^{1/4} with M05×1013  MM_0 \approx 5 \times 10^{13}\;\mathrm{M}_{\odot}. This relation is qualitatively similar to stellar mass-halo mass relations derived from abundance matching, but exhibits less scatter.

Keywords

Cite

@article{arxiv.2603.06479,
  title  = {The Baryonic Mass-Halo Mass Relation of Extragalactic Systems},
  author = {Stacy McGaugh and Tobias Mistele and Francis Duey and Konstantin Haubner and Federico Lelli and Jim Schombert and Pengfei Li},
  journal= {arXiv preprint arXiv:2603.06479},
  year   = {2026}
}

Comments

Accepted for publication in the Astrophysical Journal. 36 pages, 9 figures