Indirect dark matter search with YBJAS Observatory Outline

Indirect dark matter search with YBJ-AS Observatory Outline 1. 2. 3. 4. 5. Introduction Status of ground-based observations Data analysis with AS experiment Results Conclusions Wu hanrong on behalf of YBJ-ASg collaboration 2008. 09. 24 Te. VPA-IV@IHEP

Indirect Dark Matter search Astrophysics : Dark matter halo Gamma-ray flux from WIMP annihilation: From Observation Particle Physics

Target of indirect search 1. Galactic Halo 2. external galaxies 3. galaxy clusters 4. substructures 5. Galactic Center(GC) 6. Local Group galaxies 7. Mini-spikes around IMBH

Indirect DM search—ground based observatory IACT arrays Advantage: Good angular resolution; gamma/hadron discrimination Disadvantage: limited FOV and duty cycle Advantage: large FOV, 90% duty cycle Disadvantage: no good gamma/hadron identification EAS arrays

Data analysis with AS experiment

Tibet AS Observatory ― a. s. l. 4300 m (YBJ , Tibet) ― 606 g/cm 2 ― Large field of view ― Duty cycle (>90%) ― Mode Energy: ASγ(~3 Te. V) ARGO ASγ

Schematic map of the array and data using in analysis Tibet-IIIB 4 Tibet-III Run period space Mode Energy Angular resolution area 1999. 11~2004. 10 7. 5 m ~3 Te. V ~0. 90 ~22050 m 2 Statistic (after selection): ~1. 86*10^10

Ø analysis method Equal 迭代

全天图以及M 31显著性 1. M 31(10. 7, 41. 3) Non: 2876965 Noff: 2875325. 3 Nexc: 1639. 7 Significance: 0. 97 M 31 2. No high siginificant point (>5 sigma) except known source crab and Mrk 421 is detected

1. 90%C. L. limit— M 31

2. 90%C. L. limit— substructure -------substructure (>5 Significance for BKG ) Significance for BKG+DM signal

2. 90%C. L. limit— substructure

Conclusions • Detect no any substructure in the field of YBJ ASgamma observatory • Detect no DM from M 31 • 90% C. L. upper limit on “thermally averaged annihilation cross section” between 10^-19 cm^3 s^-1 and 10^22 cm^3 s^-1 is given • Future search, ARGO-YBJ(~300 Ge. V)