Resolve the competing roles of halo mass and halo concentration

Determine whether halo mass or halo concentration dominates the depth of the gravitational potential at fixed stellar mass and thereby controls the mass-loading factor and mass–metallicity relation.

Background

Within the minimal cosmological gas-flow model, halo mass affects the three scaling relations only indirectly through stellar mass, because the star formation efficiency and mass-loading factor are parameterized as functions of stellar mass and redshift rather than halo mass.

The authors note that a physically plausible halo-mass dependence of outflows would introduce halo-mass dependence into the mass–metallicity relation. However, simulations indicate that halo mass and halo concentration may contribute in opposite or competing ways to potential depth, leaving the dominant effect unresolved.

References

But the direction of that dependence is not obvious. \citet{wangGravitationalPotentialDrives2026} found, using the COLIBRE simulation, that at fixed stellar mass, the halo mass anti-correlates with the halo concentration, while both contribute positively to the depth of the potential, so which of the two dominates is not settled.

— Inflow-driven galaxy evolution - II: A hierarchy in the scaling relations of star-forming galaxies  (2610.12394 - Wang et al., 8 Oct 2026) in Section 5.4, “The role of halo mass”