Non-baryonic dark matter

Abstract

The need for dark matter is briefly reviewed. A wealth of observational information points to the existence of a non-baryonic component. To the theoretically favoured candidates today belong axions, supersymmetric particles, and to some extent massive neutrinos. The theoretical foundation and experimental situation for each of these is reviewed. In particular, indirect detection methods of supersymmetric dark matter are described. Present experiments are just reaching the required sensitivity to discover or rule out some of these candidates, and major improvements are planned over the next few years.

Particle annihilation in cold dark matter micropancakes

“…Many candidates for particle dark matter separate out of the early expansion symmetrically, with equal numbers of particles and antiparticles that slowly annihilate at late times. For some of the most plausible weakly interacting massive particle ("WIMP" [1][2][3]) candidates, such as neutralinos, these annihilations produce GeV to TeV photons and other observable energetic species at a rate which is potentially observable and can be used to constrain the particle parameters [4][5][6][7][8][9][10][11][12][13][14][15]. Annihilations may be a source of high energy photons already seen in EGRET data, including diffuse emission (e.g.…”

“…The physics of the annihilation is straightforward to calculate within the framework of any given particle candidate [2,3], but because the annihilation rate is proportional to the square of the particle density n, the calculated rate of annihilations and their spatial distribution depend on astrophysically complex features of the detailed small-scale spatial distribution of the dark matter particles. The best calculations [15] use high-resolution N-body simulations to compute the dark matter distribution including clumpy relic substructure within halos [21,22] and high density central cusps [21][22][23][24][25], both of which are important to the annihilation rate and the expected appearance of the radiation on the sky.…”