Positrons from Dark Matter Annihilation.

32 Pages·2008·0.75 MB·English

by  Roberto A. Lineros,,,

PositronsfromDarkMatterAnnihilation.
Roberto A. Lineros R.
Universit`a degli studi di Torino
Based on:
T. Delahaye, R.L, F. Donato, N. Fornengo and P. Salati.
Phys. Rev. D 77, 063527 (2008)
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Motivation
To study positron/electron Cosmic Rays (CR) signals and its
potential to reveal new exotic signals.
To study indirect searches of galactic Cold Dark Matter (CDM)
To study uncertainties related to particle and astrophysics, for
disentangle new signals from background.
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Outline
• Cold Dark Matter
* Properties, distribution, candidates.
• CR and propagation
* Two–Zone Propagation Model, Transport Equation (TE).
• Positron/Electron CRs
* TE and solutions, Halo Function
* Fluxes, Positron fraction, comparison with data
* Predictions for PAMELA and AMS02
• Conclusions
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Cold Dark Matter
Large structures dynamics, gravitational lensing, CMB observation,
BBN, BAO . . .
• Electrically neutral
• Almost collisionless matter
• Non-barionic
• Cold
from combined measurements give :
(E. Komatsu et al. 2008)
2
Ω h ≃ 0.105
CDM
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CDM in galaxies
It is well accepted that CDM forms
structures.
and galaxies are embedded into CDM
haloes.
(Mathis et al. 2002)
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CDM in galaxies
The CDM haloes are generically described by a smooth distribution.
(β−γ)/α
α
r γ 1 + r /r
⊙ ⊙ s
ρ(r) = ρ
⊙ α
r 1 + r/r
(cid:0) s (cid:1) !
(cid:16) (cid:17)
(cid:0) (cid:1)
+
Milky Way’s case:
r = 8.5[kpc], z = 0[kpc]
⊙ ⊙
3
ρ = 0.3[GeV/cm ]
⊙
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CDM in galaxies
Most common profiles are:
Halo profile α β γ r [kpc]
s
Cored isothermal 2 2 0 5
NFW 1 3 1 20
Moore 1.5 3 1.3 30
100
isothermal
] NFW
3
− 10 Moore
m
c

V
e
G 1
[

M
0.1
D
C
ρ
0.01
0.1 1 10 100
r [kpc]
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DM theoretical perspectives
The DM’s nature is not completely clear. We just know many
properties of it.
Candidates for a DM particle candidate are proposed in theories
BSM:
• Neutralinos, sneutrinos, gravitinos from SUSY-side.
• Kaluza-Klein particle from Extra-Dimension.
• Heavy neutrinos, axions . . .
• among others.
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DM searches
There are different ways to search for DM:
Direct detection:
By measuring recoil energy produced by elastic scattering between
detector and DM particle.
Experiments: CDMS, CRESST, EDELWEISS , DAMA, among
others.
DM production:
For some BSM models, LHC will be able to produce DM candidate
particles.
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DM searches
Indirect detection:
CDM may annihilate and act as an exotic source of CR, photons,
neutrinos, etc.
Experiments: HEAT, CAPRICE, AMS, PAMELA, AMANDA, EGRET,
MASS . . .
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