Post on 13-Jan-2016
description
Wu hanrong on behalf of YBJ-ASg collaboration
2008.09.24 TeVPA-IV@IHEP
Indirect dark matter search with YBJ-AS Observatory
Outline1. Introduction2. Status of ground-based observations 3. Data analysis with AS experiment4. Results5. Conclusions
Indirect Dark Matter search
From Observation
Gamma-ray flux from WIMP annihilation:
Particle Physics
Astrophysics : Dark matter
halo
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
EAS 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 identifintification
Data analysis with AS experiment
Tibet AS Observatory
―a.s.l. 4300 m (YBJ , Tibet)―606g/cm2
―Large field of view―Duty cycle (>90%)―Mode Energy: ASγ(~3TeV)
ASγ
ARGO
Run period space Mode EnergyAngular resolution area
Tibet-III 1999.11~2004.10 7.5m ~3TeV ~0.90 ~22050m2
Schematic map of the array and data using in analysis
Tibet-IIIB4
Tibet-II
Statistic (after selection): ~1.86*10^10
analysis method
, on onI N on
on
NI
off
off
NI
, off offI N
Equalon
onoff
NI
N
( , ) ( , )I i j I i j和迭代
全天图以及 M31 显著性
2. No high siginificant point (>5sigma) except known source crab and Mrk421 is detected
1.M31(10.7,41.3)
Non: 2876965
Noff: 2875325.3
Nexc: 1639.7
Significance: 0.97M31
1. 90%C.L. limit— M31
)5.6(1 substr)4.7(2 substr
2. 90%C.L. limit— substructure
-------substructure (>5 )
Significance for BKG Significance for BKG+DM signal
0)5( obsN
2. 90%C.L. limit— substructure
Conclusions
• Detect no any substructure in the field of YBJ ASgamma observatory
• Detect no DM from M31
• 90% C.L. upper limit on “thermally averaged annihilation cross section” between 10^-19cm^3s^-1 and 10^-22cm^3s^-1 is given
• Future search, ARGO-YBJ(~300GeV)
Thanks!
1. 90%C.L. Flux limit— M31
90%C.L. flux limit :
m
TeVeff
m
TeV
m
TeV
LC
dEEfST
dEEf
dEEf
3.0
1
90%C.L.
1
..%90
)(
)(N
)(
Av
LC
LC
..%90
..%90
DM spectrum
From Observation
Monte Carlo
2. 90%C.L. Flux limit— substructure-----Number of substructure for 800 toy MC trials
0)5( obsN
BKG BKG+DM signal