What question did this study set out to answer?

The aim is to physically derive the pseudo-isothermal halo profile and evaluate its accuracy using galaxy data.

April 5, 2026Open Access

Dark Matter as Sub-threshold Substrate Excitation: Physical Derivation of the Isothermal Halo Profile and Test against 150 SPARC Galaxies

Key Points

The aim is to physically derive the pseudo-isothermal halo profile and evaluate its accuracy using galaxy data.
Derivation of halo profile using the U-Cell Model (UCM) framework.
Analytical calculation of the universal cold parameter without free parameters.
Testing the derived model against data from 150 SPARC galaxies.
Median χ² value of 0.73 indicates a good fit to the galaxy data.
71% of the fits show χ² values less than 2.
Notable deterioration of fit at high masses interpreted as baryonic feedback effects.

Abstract

Physical first-principles derivation of the pseudo-isothermal halo profile ρ (r) = ρ₀/ (1+ (r/rc) ²) within the U-Cell Model (UCM). The universal cold parameter fcold = √ (2−π/2) ≈ 0. 6551 is derived analytically from the substrate dispersion relation without free parameters. Tested against 150 SPARC galaxies (Li et al. 2020): median χ² = 0. 73, 71% of fits with χ² < 2. The systematic deterioration at high masses is physically interpreted as the onset of baryonic feedback beyond the current UCM formulation.

Dark Matter as Sub-threshold Substrate Excitation: Physical Derivation of the Isothermal Halo Profile and Test against 150 SPARC Galaxies

Key Points

Abstract

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