The discovery that there is more non-stellar ordinary mass in galaxies and galaxy clusters than previously known makes MOND perform better than than previously believed.
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.
Dong Zhang, Akram Hasani Zonoozi, Pavel Kroupa, "Revisiting the missing mass problem in MOND for nearby galaxy clusters" arXiv:2602.06082 (February 4, 2026) (accepted by PDR).
4 comments:
nearby galaxy clusters and 20% not account for
The two sigma range around 88% is 79.8% to 98.8%. So, it is almost consistent with no missing mass, and certainly implies less missing mass than previous estimates.
could neutrinos make up the missing mass ?
The mass distribution in and around the Local Group
Ewoud Wempe, Simon D. M. White, Amina Helmi, Guilhem Lavaux & Jens Jasche
Nature Astronomy (2026)Cite this article
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Abstract
Our Galaxy, Andromeda and their companion dwarf galaxies form the Local Group. Most of the mass in and around it is believed to be dark matter rather than gas or stars, so its distribution must be inferred from the effect of gravity on the motion of visible objects. Modelling efforts have long struggled to reproduce the quiet Hubble flow around the Local Group, as they require unrealistically little mass beyond the haloes of the two main galaxies. Here we revisit this using ΛCDM simulations of Local Group analogues with initial conditions constrained to match the observed dynamics of the two main haloes and the surrounding flow. The observations are reconcilable within ΛCDM, but only if mass is strongly concentrated in a plane out to 10 Mpc, with the surface density rising away from the Local Group and with deep voids above and below. This configuration, dynamically inferred, mirrors known structures in the nearby galaxy distribution. The resulting Hubble flow is quiet yet strongly anisotropic, a fact obscured by the paucity of tracers at high supergalactic latitude. This flattened geometry reconciles the dynamical mass estimates of the Local Group with the surrounding velocity field, thus demonstrating full consistency within the standard cosmological model.
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