The cusp-halo relation

2025/06/03 by M. Sten Delos, Delos, M. Sten · 2 citations
Computer Science · #Astrophysics of Galaxies (astro-ph.GA) #Computational Physics and Python Applications #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences

paper · pdf · doi:10.48550/arxiv.2506.03240

openalex publication_date 2025/06/03 · openalex created_date 2025/10/14 · openalex updated_date 2026/07/31

Abstract

Simulations have established that each halo of collisionless dark matter is expected to contain a ρ= A r^-1.5 density cusp at its center. This prompt cusp is a relic of the halo's earliest moments and has a mass comparable to the cutoff scale in the spectrum of initial density perturbations. In this work, we provide a framework to predict for each halo the coefficient A of its central cusp. We also present a "cusp-NFW" functional form that accurately describes the density profile of a halo with a prompt cusp at its center. Accurate characterization of each halo's central cusp is of particular importance in the study of warm dark matter models, for which the spectral cutoff is on an astrophysically relevant mass scale. To facilitate easy incorporation of prompt cusps into any halo modeling approach, we provide a code package that implements the cusp-halo relation and the cusp-NFW density profile.

Citations

• 21-cm Constraints on Dark Matter Annihilation after an Early Matter-Dominated Era
• Steepest Growth in the Primordial Power Spectrum from Excited States at a Sudden Transition
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• The distribution of dark matter in galaxies
• Planck 2018 results. VI. Cosmological parameters

Cited by

• Testing warm dark matter with kinematics of the smallest galaxies
• The role of prompt cusps in driving the core collapse of SIDM halos

Related

• The Inner Density Cusp of Cold Dark Matter Halos
• Phase-space simulations of prompt cusps: simulating the formation of the first haloes without artificial fragmentation
• The role of prompt cusps in driving the core collapse of SIDM halos
• The central cusps in dark matter halos: fact or fiction?
• A Dark-Matter Halo Profile allowing a Variable Cusp-Core with Analytic Velocity and Potential