Gamma rays annihilated from substructures of the Milky Way and Quintessino dark matter Bi Xiao-Jun Institute of High Energy Physics, Chinese Academy of Sciences

Candidates of the cold dark matter There are hundreds of theoretical models in the literature Weakly Interacting Massive Particles (WIMPs) as thermal relics of Big Bang is a natural candidate of CDM. such as neutralinos, KK states, Mirror particles … The WIMP miracle: for typical gauge couplings and masses of order the electroweak scale,  wimp h 2  0.1 (within factor of 10 or so)

Detection of WIMP Direct detection of WIMP at terrestrial detectors via scattering of WIMP of the detector material. Indirect detection looks for the annihilation products of WIMPs, such as the neutrinos, gamma rays, positrons at the ground/space-based experiments   Direct detection  p e+e+  _ indirect detection

Indirect detection Flux is determined by the products of two factors The first factor is the strength of the interaction, determined completely by particle physics The second factor is by the distribution of DM The factor is enhanced at the clumps of DM, such as at the GC, subhalos, or at the core of Sun and Earth. The flux depends on both the astrophysics and the particle aspects.

SUSY factor Process Parameters ： Method ： scan the SUSY 7-dimensional parameter space and constrain it by the present experimental bounds, then calculate the SUSY factor by DarkSUSY Constraints ： 1 ） self consistent ； 2 ） neutralino being the LSP ; 3 ） spectrum given by PDG ； 4 ） other constraints ； 5 ） relic density by WMAP 2σ

Constraints from astronomical observations The EGRET, CANGAROO AND HESS HESS,CANGAROO EGRET

The SUSY factor The integrated flux due to different threshold energy. Points are different SUSY model

Substructure (subhalo) of the MW Since We can search the annihilation signal from the GC or the subhalos. However, the GC is very complex due to SMBH and other baryonic processes. We investigate the case of subhalos.

Distribution of the subhalos N-body simulation (MNRAS352,535 (2004) ) gives the probability for a subhalo of the mass m and at the position r with M, host mass, r cl =0.14r virial andα ＝－ 1.9 The tidal effect will strip the particles beyond a tidal radius, We get the distribution as

Profiles of the subhalos Two generally adopted DM profiles are the Moore and NFW profiles They have same density at large radius, while different slope as r->0 NFW: Moore:

Concentration parameter of subhalos The are determined by the virial mass and concentration parameter.For larger C, the DM is more centrally concentrated. A semi-analytic model: the collapse epoch is determined by the collapsing time of a fraction of the object mass, σ(M * =FM)=δ sc ; The concentration parameter is determined by another free parameter c(M,z)=K(1+z c )/(1+z). We have taken a standard scale invariant spectrum and the cosmological parameter as in the figure. From the figure, the concentration parameter decreases with the virial mass.

Statistical results The curves are due to different author’s simulations. The threshold is taken as 100 GeV. The susy factor is taken an optimistic value for neutralino mass between 500 GeV and 1TeV. Results are within the field of view of ARGO.

Fit the results The results can be well fitted by inverse power law.

Sensitivity of detectors The 3σsensitivity of the detectors as function of the threshold energy. For one year cumulative data of ARGO and HAWC, one month of GLAST and 250 hours VERITAS.

Detectability

Detection of heavy DM The cherenkov detector has high sensitivity while very small field of view The GLAST has small effective area and low threshold energy and large filed of view; suitable for small mass neutralino Due to S.M. Koushiappas, A.R. Zentner, T.P. Walker, PRD69 (2004) , M χ > 500GeV can not be detected by GLAST+ cherenkov Due to our calculation, heavy neutralino can be detected by ground EAS detector, ARGO/HAWC. ground space cherenkov EAS angular reso exce （ <0.1 o ) good(1 o ) exce(~0.1 o ) obser time short (10%) long (~90%) long(~100%) effective area large(10 4 M ) large(10 4 M 2 ) small(~1M 2 ) field of view small( 2π ） bkg good （ ~99.9% ） bad(<70%) good energy reso good(~20%) not bad (~100%) good(<10%, small syst error ）

Quintessino － super partner of Quintessence － as DM To understand the relation, can DM and DE be described in a unified way? Extending the DE to SUSY.

Non-thermal production of quintessino Its interaction strength is much smaller than the weak scale They can not be generated efficiently through the thermal interaction, however they be produced through non-thermal production, such as via decay of heavy relics If the decay is later than BBN, it will affect the BBN and CMB observations and therefore by constrained.

Interaction between quintessence and the matter Extremely light mass Direct coupling is very weak from constraints of fifth force Quintessence may be axion-like pseudo- Goldstone, we demand the global shift symmetry for the interaction Shift symmetry does not destroy the flatness of quintessence potential

Anomalous coupling of Qintessence Qintessence and photon Its supersymmetric form Experimental constraint 。

Derivative coupling Consider the derivative coupling We get its supersymmetric form We have the shift symmetry Stellar evolution, SN87A, familon search

Constraints from BBN The parameter space with red color is ruled out by BBN. The allowed parameter is shown as the net.

Effects of Quintessino DM Due to large velocity of non- thermal production, the matter power spectrum at subgalactic scales is suppressed Affect BBN ， suppress 7 Li abundance and predicts correct value given by exp. Predicts a massive, long life time and charged particel Lin, Huang, Zhang, Brandberg 01 Bi, Li, Zhang, 2004

production by cosmic neutrinos We consider the following process Flux of high energy cosmic neutrinos Cross section of neutrino and nucleon Scattering of neutrinos by the earth matter Propagation of stau in the earth

Flux of cosmic neutrinos

Cross section of the interaction CTEQ6 PDF is used to calculate all the quark flavor and its antiparticle and both CC and nc process

Propagation of stau Via ionization and radiation Follow the equation is due to ionization

production by cosmic rays High energy cosmic neutrinos interacts with the earth matter, the supersymmetric particle and finally the NLSP particle is produced L3+C or IceCube can detect the Bi, wang, zhang, zhang 04

Conclusion We propose to detect the DM (neutralino > 500 GeV) annihilation from subhalos by the ground EAS array (ARGO/HAWC) and calculate the chance of detect the signal. We propose a new superWIMP DM candidate, connecting the DM and DE in one SUSY field, and study its effects by detection of heavy charged particles.