Using GLAST to find WIMP annihilation signatures

1
Using GLAST to find WIMP annihilation signatures

• Larry Wai
• SLAC-Stanford

2
Cosmological Energy Budget

• Component Fraction
• visible baryons 0.01
• dark baryons 0.04
• non-baryonic dark matter 0.25
• dark energy 0.70
• total 1.00
• Components of the universe measured in units of
  critical density

3
Non-Baryonic Dark Matter Candidates
Particle Type Production Process Mass Observation methods
Axions Big Bang Non-thermal 10-5 eV Direct conversion to radio waves
Neutrinos Big Bang Thermal 10-1 eV Analysis of large scale structure
WIMPs Big Bang Thermal 102 GeV Direct scattering on nuclei, Indirect observation of annihilation products
4
WIMP candidates motivated by particle experiments
Theory / Motivation WIMP Name Particle Type Stability Principle
Supersymmetry theoretical foundations of the Standard Model Lightest SUSY particle Majorana fermion I.e. neutralino R-Parity conservation
Extensions of Standard Model Left-right asymmetries in Standard Model neutrino sector Iso-singlet neutral lepton Majorana fermion No mixing with neutrinos I.e. zero left-right mixing
Extra dimensions foundations of gravity and the Standard Model Lightest KK Particle Boson (KK photon) or fermion (KK neutrino) Universal extra dimension KK-parity conservation
5
WIMP Annihilation Processes
6
GLAST WIMP Search Regions

• Galactic center
• Galactic satellites
• Galactic halo
• Extra-galactic

7
Galactic Center Dark matter density growth near
a supermassive black hole

• Conservation of angular momentum
• mv2/2 GmM/r
• M MDM MBH
• ri mvi rf mvf
• riMi rfMf

• Conservation of dark matter
• MiDMMfDM
• ri a r-g , rf a r-A
• ri3-g a rf3-A
• Mi MiDM, Mf MfBH
• ri4-g a rf
• A(9-2g)/(4-g)

Ullio, Zhao, and Kamionkowski, Phys.Rev.D64043504
(2001)
8
Galactic Center Dark matter near Sgr A

• Dark matter density r
• r r-2 for rgtfew kpc
• r r-g for 10pcltrltfew kpc
• r r-A for 10-2pcltrlt10pc
• r rcore mWIMP/ltsAvgt/tBH for 10-6pc lt r lt
  10-2pc
• r 0 for r lt 10-6pc

9
Galactic Center Gamma ray observation

• Mayer-Hasselwander (1998) - EGRET point source
  close to the galactic center
• Spatial analysis
• 100MeV-300MeV (l -0.75deg)
• 300MeV-1GeV (l -0.30deg)
• gt 1GeV (l 0.05deg)
• gt 5GeV (l 0.20deg)

HESS?
Cesarini, Fucito, Lionetto, Morselli, Ullio (2003)
Hooper and Dingus (2002)
Mayer-Hasselwander et.al. (1998)
10
Space versus ground based telescopes
Feng , Matchev, Wilczek PRD63045024 (2001)

• GLAST is superior for continuum radiation
• GLAST provides a list targets for ACTs
• ACTs are more sensitive in the WIMP line region

WIMP annihilation flux
VERITAS / HESS
11
Galactic Satellites signatures

1. Lack of variability
2. Lack of counterparts
3. p0 decay energy spectrum (i.e. peak at 67.5
   MeV)
4. Cutoff of energy spectrum / line at mass of WIMP
5. Inverse Compton scattering of electrons from p/-
   decay

12
Galactic satellites diffuse emission
13
Galactic halo n-body simulation
14
Extra-galactic Spectral Signatures
15
WIMP annihilation science related prep work for
launch

• Besides standard analyses
• point sources
• counterpart searches
• galactic diffuse
• extragalactic diffuse
• Need to specialize in
• Variability (or lack of)
• Extended sources
• 20-100 MeV spectrum
• line identification
• Galactic center