Quintessino model and neutralino annihilation to diffuse gamma rays

1. Quintessino model and neutralino annihilation to diffuse gamma rays X.J. Bi (IHEP) 2006.8.8

2. Outline • A unified model of dark matter and dark energy ---- quintessino model • The Milky Way diffuse gamma rays and contribution from neutralino annihilation

3. Unified model of dark matter and dark energy • Possible candidates of dark energy are the cosmological constant or a scalar field --- the quintessence field (a dynamical fundamental scalar field). • The motivation is to build a unified model of dark matter and dark energy in the framework of supersymmetry. • requiring a shift symmetry of the system, the quintessence is always kept light and the potential is not changed by quantum effects. If is the LSP, it is stable and forms DM.

4. Shift symmetry and interaction • To keep the shift symmetry the quintesssence field can only coupled with matter field derivatively. We consider the following interactions and derive their supersymmetric form:

5. 106 Non-thermal production of quintessino WIMP  quintessino + SM particles (WIMP=weakly interacting massive paricle) SM quintessino WIMP Since the interaction of quintessino is usually suppressed by Planck scale, it is generally called superWIMP. e.g. Gravitino LSP quintessino LKK graviton

6. Charged slepton, sneutrino Or neutralino/chargino EM, had. cascade  change CMB spectrum  change light element abundance predicted by BBN Candidates of NLSP WIMP  quintessino + SM particles 105 s  t  107 s OK Charged slepton NLSP is allowed by the model

7. Effects of the model • Suppress the matter power spectrum at small scale. • Faraday rotation induced by quintessence. • Suppress the abundance of 7Li. • The lightest super partner of SM particles is stau.

8. Look for heavy charged particles • A charged scalar particle with life time of 105 s  t  107 s and mass 100 GeV< M < TeVis predicted in the model. • High energy comic neutrinos hit the earth and the heavy particles are produced and detected at L3C/IceCube • Due to the R-parity conservation, always two charged particles are produced simultaneously and leave two parallel tracks at the detector.

9. Production at colliders • If is the LSP of SM, all SUSY particles will finally decay into and leave a track in the detector. • Collecting these , we can study its decay process. (We can even study gravity at collider.) • LHC/ILC can at most produce Buchmuller et al 2004 Kuno et al., 2004 Feng et al., 2004

10. Diffuse gamma rays of the MW • COS-B and EGRET (20keV~30GeV) observed diffuse gamma rays, measured its spectra. • Diffuse emission comes from nucleon-gas interaction, electron inverse Compton and bremsstrahlung. Different process dominant different parts of spectrum, therefore the large scale nucleon, electron components can be revealed by diffuse gamma.

11. GeV excess of spectrum • Based on local spectrum gives consistent gamma in 30 MeV~500 MeV, outside there is excess. • Harder proton spectrum explain diffuse gamma, however inconsistent with antiproton and position measurements.

12. Hard proton or electron injection index

13. Contribution from DM

14. Fit the spectrum • B~100 • Fi,j -----

15. Substructure (subhalo) of the MW

16. Calculate cosmic rays • Adjust the propagation parameter to satisfy all the observation data and at the same time satisfy the egret data after adding the dark matter contribution

17. Results of different regions • a

18. Conclusion • A DM-DE unified model requires stau being the NLSP (gravitino model). Make different phenomenology. • Taking the contribution from DM annihilation into account the EGRET data can be explained perfectly. (Without DM it is difficult to explain the GeV excess even there are large uncertainties of cosmic ray propagation). • EGRET data requires the neutralino mass be in the range 40~50 GeV and DM distribution be very cuspy.