http://arxiv.org/abs/2109.12244
Inverse mass cascade is a key feature of the intermediate statistically steady state of self-gravitating collisionless flow (SG-CFD). This paper focus on the effects of mass cascade on halo energy, momentum, size, and density. Halo with fast mass accretion has an expanding core. Mass cascade forms a new layer of mass that deforms the original halo and induces nonzero radial flow (outwards for core and inwards for outer regions). The inward/outward flow leads to an extra length scale (scale radius) that is not present in isothermal profile. Halo concentration $c=3.5$ can be derived for fast growing halos. For cusp-core controversy, a double-power-law density is proposed as a result of radial flow. The inner/outer density are controlled by halo deformation rate and halo growth, respectively. The slower deformation at center, the steeper density. For fast growing halos, radial flow at center is simply Hubble flow that leads to the existence of central core. Mass cascade leads to nonzero halo surface energy/tension and radial flow that enhances the random motion in outer region. An effective exponent of gravity $n_e=-1.3$ (not -1) is obtained due to halo surface energy. Evolution of halo size follows geometric Brownian motion and lognormal distribution. The Brownian motion of particles in randomly evolving halos leads to Fokker-Planck equations for particle distribution that is related to radial and osmotic flow. Complete solutions of particle distribution are presented based on a simple model of osmotic flow. The proposed model agrees with simulation for a wide range of halo group sizes. With reference pressure/density defined at center, equation of state can be established for relative pressure/density. The center pressure, density, and dispersion are presented. The core size $x_c$ is obtained where Hubble flow is dominant. Simple closures are proposed for self-consistent halo density.
Z. Xu
Tue, 28 Sep 21
66/89
Comments: N/A