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Are halos of collisionless cold dark matter collisionless?
Chung-Pei Ma1, Michael Boylan-Kolchin
1Departments of Astronomy and Physics, University of California at Berkeley, Berkeley, California 94720, USA.
Physical Review Letters
|August 25, 2004
Summary
Gravitational scattering by subhalos can explain the diverse inner density profiles of dark matter halos. This process diffuses dark matter particles, reconciling halo structure with subhalo abundance observations and simulations.
Area of Science:
- Cosmology
- Astrophysics
- Particle Physics
Background:
- The inner density profiles of dark matter halos exhibit significant variation.
- The abundance of subhalos within larger dark matter halos is a key cosmological observation.
Purpose of the Study:
- To investigate the connection between subhalo abundance and dark matter halo inner density profiles.
- To explore the role of gravitational scattering by subhalos in shaping halo structure.
Main Methods:
- Numerical simulations of dark matter halo evolution.
- Modeling gravitational scattering of dark matter particles by subhalos.
- Analyzing tidal mass loss effects on subhalos.
Main Results:
- Subhalos induce diffusion of collisionless dark matter particles in central halo regions.
- This diffusion, coupled with subhalo tidal mass loss, creates scatter in inner density profiles.
- The proposed mechanism explains the observed range of halo profiles.
Conclusions:
- Gravitational scattering by subhalos is a viable explanation for the diversity of dark matter halo density profiles.
- This process links subhalo abundance to halo structure, resolving a key discrepancy in dark matter research.
- The findings have implications for understanding dark matter distribution and halo formation.
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