Year: 2026
Type: article
Abstract: In the framework of Milgromian dynamics (MOND), galaxy clusters are known to exhibit a residual missing mass problem, with the baryonic mass falling short of the dynamical mass by about a factor of two. The baryon content of clusters is dominated by the intracluster medium (ICM), while the stellar contribution depends sensitively on the assumed stellar initial mass function (IMF). We re-evaluate the stellar and remnant masses in galaxy clusters by adopting the integrated galaxy-wide initial mass function (IGIMF) theory, which accounts for the dependence of the IMF on galaxy properties and star formation histories. Massive elliptical galaxies, characterized by high metallicities and short formation timescales, are inferred to form with top-heavy IMFs, leading to a substantial population of stellar remnants. Using observational data from WINGS and 2MASS for 46 nearby (z < 0.1) galaxy clusters, we compute stellar, remnant, and intracluster light masses and combine them with previously derived ICM masses. The resulting total baryonic masses are compared to MOND dynamical masses inferred from hydrostatic equilibrium. We find that the baryonic mass in stars, remnants and the ICM accounts for at least $88^{+5+2}_{-4-1}\%$ of the MOND dynamical mass. This constrains the kick velocities of the remnants and substantially alleviates the missing mass problem for galaxy clusters in MOND.
DOI: 10.1103/mp3f-q5dc
Authors: Dong Zhang, Akram Hasani Zonoozi, Pavel Kroupa
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Award: G5551012850
OpenAlex ID: W7125378675