2025/07/01 by Shields, Tristen, Salazar, Edgar M., Rozo, Eduardo +3
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2507.00410
Among the most fundamental properties of a dark matter halo is its density profile. Motivated by the recent proposal by García et al. [R. García et. al., MNRAS 521, 2464 (2023)] to define a dynamical halo as the collection of orbiting particles in a gravitationally bound structure, we characterize the mean and scatter of the orbiting profile of dynamical halos as a function of their orbiting mass. We demonstrate that the orbiting profile of individual halos at fixed mass depends on a single dynamical variable -- the halo radius r\rm h -- which characterizes the spatial extent of the profile. The scatter in halo radius at fixed orbiting mass is ≈ 16%. Only a small fraction of this scatter arises due to differences in halo formation time, with late-forming halos being more compact (smaller halo radii). Accounting for this additional correlation results in an ≈ 11% scatter in halo radius at fixed mass and halo formation time.