Particle annihilation in cold dark matter micropancakes
Abstract
Cold primordial particle dark matter forms with a distribution in six-dimensional phase space closely approximating a three-dimensional sheet. Folds in the mapping of this sheet onto configuration space create ubiquitous sheetlike caustics (``micropancakes''). A typical weakly interacting massive particle dark matter halo has many micropancakes, each with a scale comparable to the halo itself, a width about 10-8 of the halo size and a typical maximum density up to about 104 times the halo mean. It is suggested here that the total annihilation rate of dark matter particles is dominated by particles close to these micropancakes, so radiation is emitted predominantly from highly contorted two-dimensional surfaces rather than a filled volume. The total annihilation rate of particles is about a factor of 5 higher than predicted from N-body simulations, which cannot resolve these features. Micropancakes also produce sharp line discontinuities in the surface brightness of annihilation radiation.
- Publication:
-
Physical Review D
- Pub Date:
- September 2001
- DOI:
- 10.1103/PhysRevD.64.063515
- arXiv:
- arXiv:astro-ph/0104106
- Bibcode:
- 2001PhRvD..64f3515H
- Keywords:
-
- 95.35.+d;
- 98.62.Gq;
- Dark matter;
- Galactic halos;
- Astrophysics
- E-Print:
- 8 pages, 2 figures, Latex, revised version submitted to Phys. Rev. D with more detailed explanation and new references added