How does inner dark matter structure vary across galaxy mass scales?

Bayesian rotation-curve fits to SPARC galaxies probe the diversity of halo inner slopes and place them alongside dwarf satellites, groups and clusters.

Cusp-to-Core Transition of Dark Matter Halos across Galaxy Mass Scales

Cusp-to-Core Transition of Dark Matter Halos across Galaxy Mass Scales. Hayashi, Kohei; Kaneda, Yuka; Mori, Masao; Shinozaki, Michi, Publications of the Astronomical Society of Japan, 78, pp. 745-763 (2026).

arXiv:2507.22155 Publication · DOI

Approach

Flexible halo profiles are fitted to high-quality SPARC rotation curves. Inner structure is compared using dark matter surface density within 0.01 times the radius of maximum circular velocity.

Main result

The SPARC sample spans steep central cusps and shallow cores. Many galaxies have lower inner densities than cuspy cold-dark-matter predictions, while lower-mass dwarfs and higher-mass clusters tend to track cuspy profiles.

Scientific implications

The comparisons provide an empirical test of a mass-dependent cusp-to-core transition and of baryonic processes in shaping halo centres.

Scope and limitations

Rotation-curve modelling and observational uncertainties prevent a definitive attribution to baryonic feedback. The results do not establish that every galaxy at a given mass has the same inner profile.