Dark matter properties from universal scaling laws and energy cascade in dark matter flow
ORAL
Abstract
We present a new approach to estimate dark matter particle mass, size, density, and many other properties based on a cascade theory for the flow of dark matter, similar to the cascade in hydrodynamic turbulence. The energy cascade from small to large scales with a constant rate εu≈-4.6x10-7m2/s3 is a fundamental feature of dark matter flow. Energy cascade leads to a two-thirds law for kinetic energy vr2 ≈(εur)2/3 on scale r, as confirmed by N-body simulations. This is equivalent to a four-thirds law for mean halo density ρs enclosed in the halo scale radius rs such that ρs ≈εu2/3G-1rs-4/3, as confirmed by galaxy rotation curves. The smallest length scale in dark matter flow is dependent on the nature of dark matter. For collisionless dark matter, particle mass is estimated to be mX≈(-εuh5G4)1/9≈1012GeV with a size of rη ≈(-εuhG)1/3≈10-13m, where h is the Planck constant. An uncertainty principle for momentum and acceleration fluctuations is also postulated to explain the physical origin of the rate of energy cascade εu. For self-interacting dark matter, the smallest structure has a sale rη ≈εu2G-3(σ/m)3, where σ/m is the cross-section. On halo scale, the energy cascade leads to an asymptotic density slope γ=-4/3 for fully virialized halos with a vanishing radial flow, which might explain the nearly universal halo density. A modified Einasto density profile is proposed accordingly. Accompanying slides and datasets for this work can be found at https://doi.org/10.5281/zenodo.6569901.
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Publication: doi.org/10.48550/arXiv.2202.07240
Presenters
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Zhijie Xu
Pacific Northwest National Laboratory
Authors
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Zhijie Xu
Pacific Northwest National Laboratory