Dark matter and future gamma-rayobservations
133 GeV gamma-rays from galactic
center and axion emission fromdark matter	Kaz Kohri （郡和範）	 

KEK and Sokendai, Japan
This work is based on
Yamanaka, Kohri, Nojiri and Ioka (2013) in preparation
Kohri, Park, and Rott (2013) in Preparation	

Indirect detection of DM	

Thermal freezeout
Boltzmann equation
ρDMs3Hnχ σv= mDMnDM
sfrezeout

TFreezeout  mχ / 23⎛⎞σv⎜⎟2Ω χ h  0.1⎜
2⎟⎜ 0.1⎟⎝TeV ⎠()

∝Exp[-m/T]m/T	Ωχ h2 does not depend on mχPredicting TeV Physics!!!

σv = 3 × 10 −26cm 3 / s

130 GeV gamma-ray line(s)	

4.63σ	• Observation and ann. DM interpretation	

σv DM+DM→γ +γ >~ 10 −27cm 3 / sec>~ 0.1 σv

canonical

Depending on density profile(NFW,Einasto,isothermal-cored,...)For thermal production,

σv canonical =3 × 10 −26cm 3 / sec
Weniger,arXiv1204.2797	

Line width < 15 %	

Possible other sources?	
• Inverse Compton by electron with a peakstructure produced in pulsars (e+γ→e+γ)
Aharonian, Khangulyan, Malyshev, 1207.0458	

• Instrumental effects ( seen in observations ofEarth-Lim Emission)
Ackermann et al, Fermi Collaboration (2013), arXiv:1305.5597	

133 GeV gamma-ray from galactic
center in Fermi-LAT satellite data	Ackermann et al, Fermi Collaboration (2013), arXiv:1305.5597	

3.3σ	

Local

1.9σ	

Global	In their DISCUSSION and SUMMARY, they wrote “More data andstudy are needed to clarify the origin of this feature.”	

Annihilating Dark Matter?	
• One-loop suppressionDM	e	fDM	γfe	γ• Branching ratioσ (DM+DM → γ +γ )Br(DM+DM → γ +γ ) ≡σ total~ α 2 ~ 10 −4

Non-thermal DM with Large σtotal 	• Bounds on branching fraction into gamma linefrom BBN + CMB bound on total σ (IndependentHisano, Kawasaki, KK, Moroi, Nakayama, Sekiguchi (09)of profile)σ total< 700
σ γγ• Bounds on the line (γ+γ) to continuum (WW,ZZ)
σ total< 30 − 100σ γγCohen, Lisanti, Slatyer, Wacker(12), Buchmuller, Garny (12)	

Dark Matter annihilation/decay?	
• Morphology of the density profile? 	

No much differences 	Jong-Chul Park and Seong Chan Park (2012)	

Can DM emit gamma-rays without
continuum?	
See also, Endo,Hamaguchi,Liew,Mukaida,Nakayama,arXiv:1301.7536 	

• We may use axion-photon conversion undermagnetic field	
Yamanaka, Kohri, Nojiri and Ioka (2013) in preparation	What is (QCD) axion?	
l Breaking of U(1) Peccei-Quinn symmetryl Nambu-Goldstone boson (angular component) iscalled “axion”	
QCD	-Fa	

Fa	

0	Fa	

How large is Fa ?	

mπ Fπ
See also, ma ~in QCD axions (not string axions)Fa• Dark matter axion (Ωah2≦0.1)

Fa ≤ 10 GeV ⇔ 10 eV ≤ ma
12−6

• In order not to cool red giant and/or SN1987A,

10 GeV ≤ Fa
10⇔ ma ≤ 10 eV−4

Photon-ALP mixing in (string) axions 	Axion-Like Particle (ALP)	
• Lagrangian1

L = − F µνF4• Mass matrixµν+111∂ µ a ∂ a − ma a − g aγ aF µνF µν
224µ2 2 = g aγ a E • B⎛ 00⎜
M2 = ⎜ 00⎜ 0 −g Bωaγ
⎝A⎞ ⊥0⎟−g aγ Bω ⎟ A⎟m2a⎠aA⊥ A a

Dispersion relation	
• Klein-Gordon Equation (propagation along with z-axis)⎡ −∂t2 + ∂i ∂i − M 2 ⎤ Aj⎣⎦222⎡
= ⎣ω + ∂ z − M ⎤⎦ Aj = 0• Linearized equation (useful to discuss disp.-rel.)	

(ω + i∂ )(ω − i∂ ) = (ω + k )(ω − i∂ ) ~ 2ω (ω − i∂ )zzz

⎡ω − i ∂ z − M 2 / (2ω ) ⎤ Aj = 0⎣⎦zAxion coupling and mass	2⎡• Eigen values for ⎣ω − i ∂z − M / (2ω ) ⎤⎦ A j = 02⎞
1 ⎛ 2
4m1,2 =m±m+ g aγ Bω ⎟⎜ aa4ω ⎝⎠(• Coupling	α 1ga λ = ξ
2π Faa	1/Fa	)e	～～～～～ γ	γ5	～～～～～ γ	e	(ξ ~ O (1) which depends on models )See also, ma ~mπ Fπin QCD axions (not string axions)Faa↔γ oscillation probability	• Probability2⎤⎡⎛ Ε* ⎞ ⎥g Br12 ⎢ aγPa ↔γ =sin1+ ⎜ ⎟2⎜⎟⎢⎥2Ε⎛ Ε* ⎞γ ⎠⎝⎢⎣⎥⎦
1+ ⎜ ⎟⎜Ε ⎟⎝ γ⎠• For efficient oscillation,

ma 2Eγ > E* =2 g aγ Bandr ≥ rHa ≡2gaγ B

Energy range for oscillation (E>E*	)
ma ,0.1neVma
E* ==TeV2 g aγ B
g11BnG
219=10 eV
21

2ma ,0.3µ eV

2g11 BnGmm

22−3a ,10eVa,10neV=10eV
TeV
11 B10µ Gg 11gB10µG

g11 ≡ gaγ /10−11 GeV−1 , B10 µG ≡ B /10µG, ma,µeV ≡ ma / µeVPhase of oscillation (r>2/gaγB)	
g11 ≡ g aγ /10−11 GeV −1• Phase (like Hillas Condition)

gaγ Br2B10 µG ≡ B /10 µG
r10kpc ≡ r /10kpc~ g11B10 µG r10kpc > 1• Oscillation length	
10kpc
rHa =
g11 B10 µG
100Mpc=g11 BnG

Just within galaxy	Distance from Blazars	

HillasDiagram	B	

B10 µGr10kpc g11 > O (1)Blazar	
B10 Gr10 pc g11 > O (1)1

Hooper-Serpico (07)	

−2r	

Gamma-ray accessible parameters	
Observation of solar axion in CERN	

Hooper-Serpico (07)	

Future TeV-gamma observation
Cherenkov Telescope Array (CTA)	
• One order of magnitude better sensitivity atTeV

Summary	• We have not had any clear explanationsfor 133 gamma-rays observed in Fermi• We propose models in which gammarays can be converted from energetic
axion emitted from decaying DM• In future we will be check this scenarioby CTA