positron excess? physics department, tohoku university physics department, tohoku university (郡...
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Positron excess?
Physics Department, Tohoku University Physics Department, Tohoku University
(郡 和範)Kazunori Kazunori KohriKohri
- From viewpoints of both particle physics and astrophysics -
Positron Excess (PAMELA satellite reported)
Adriani et al, arXiv:0810.4995v1 [astro-ph]
/ ( ~0.6 proton diff usion)e e E
Electron and positron flux by Fermi
Abdo et al, Fermi LAT Collaboration, arXiv:0905.0025, PRL102 (09) 181101
What is the origin of e+e- excess?• Particle-physics origin
• Astrophysical origin
1. Annihilating DM
2. Decaying DM
1. Pulsars
2. Supernova Remnants (SNRs)
3. Gamma-ray burst
See Fuminobu Takahashi’s talks
See also Toshifumi Yamada’s and Patrick Fox’s talk
See Norita Kawanaka’s talk
See also Subir Sarkar’s talk
See Kunihito Ioka, arXiv:0812.4851[astro-ph] or Kawanaka’s talk
BBN, CMB, Gamma-ray, ν, gal. profile
Diffuse-gamma-ray
annisotropy
B/C
annisotropy
Another aspects of annihilating DM
1. Big Bang Nucleosynthesis (BBN)
2. Cosmic Microwave Background (CMB)
3. Gamma-ray background ( gal. and extra-gal.)
4. Neutrinos
5. …
http://map.gsfc.nasa.gov/media/060916
Dark Matter?
2CDM 0.1 h
0
ii
c
Thermal freezeoutBoltzmann equation
frezeout
3
H
nv
2
20.10.1
TeV
v
h
Freezeout / 20T m
Ωχ does not depend on mχ
Kolb & Turner
Predicting TeV Physics!!! 26 33 10 /v cm s
n
s
Positron Excess
Steady-state solution (Hisano etal, ’06)
K(E) and b(E) are taken from (Baltz-Edsjo ’99)
Diffusion model
Flux
Propagating within a few kpc, normalized to fit B/C, Boost Factor (BF) considered for clumpy distributed DM.
0.17propagation ( )/ ( ) 0.7kpc( / GeV)r EK E b E E
Hisano, Kawasaki,
Kohri, Moroi, Nakayama (09)
Positron excess
in DM annihilation
Diffusion model
Fitted to B/C ratio
23 310 /v cm s
Hisano, Kawasaki,
Kohri, Moroi, Nakayama (09)
Electron/positron cutoff
in DM annihilation
Diffusion model
Fitted to B/C ratio
23 310 /v cm s
Residual annihilation of DM even at around BBN or CMB epoch
• To fit the PAMELA and ATIC2/Fermi positron and electron signals,
23 310 /v cm s
2DMD
DMDM DMann
M DMann3 ~
H
v nn
dnHn v n
s s
dn
t
O(103) times larger than canonical value, 26 3
canonical 3 10 /v cm s
1
Big-Bang Nucleosynthesis (BBN)
Big-Bang Nucleosynthesis (BBN)
Very strong cosmological tools to study long-lived particles with lifetime of 0.01 sec – 1012 sec
Theoretical predictions are constrained by observational D, 3He, 4He, 6Li and 7Li abundances with their conservative errors.
44
38
1
18
16
1
5
10
12
2
- 4
10 GeV
10 GeV
10 GeV
200 MeV
3 M
time
10 sec
10 sec
10 sec
10 sec
0.1 sec
1 sec
10 s
eV
0.5 MeV
1ec
10 se
eV
0.1 eV
1
"temper
c
0
at ur
e"
eV13
.7 Gyr
Thermal history of the UniverseThermal history of the Universe
Planck scale
GUT phase transition?
Electroweak phase transition
QCD phase transition
Neutrino decoupling
Electron-positron annihilation
Matter-radiation equality
Photon decoupling (CMB)
Big bang
Present
Inflation and Reheating
Baryogenesis?
Big-Bang Nucleosynthesis (BBN)
17(~10 sec)
cf) 1 GeV ~ 1013K
Radiation
Matter
Scenario of BBN
1) 1 MeV ( 1sec)T t , , e,n p
Weak interaction is in equilibrium
en e p
n
p
n QExp
n T
(Q 1.29 MeV)n pm m
cf) 1 MeV ~ 1010K
2) ~ 1 MeV ( ~ 1 sec)T tFeezeout of weak interaction
•Weak interaction rate
•Hubble expansion rate
5 4~ ~ / n p n p e Wn T m
2( )~ /
( )
pl
a tH T M
a t
33
4~
0.8 MeV
p
W
T M T
H M
( 0.8 MeV ) fH T T / is fixedn pn n
freezeout
n
p f
n QExp
n T
cf) 1 MeV ~ 1010K
QExp
T
freezeout
1
7n
p
n
n
4 He4
N
pB
mY
4 He
N
n
mfreezeout
freezeout
2( / )0.25
( / ) +1( )
n p
n pn p
n n
n nn n
He4 mass fraction
4 Hen
npp
4He/ 2nn n
3) ~ 0.1 MeV ( ~ 100 sec)T t
p n D 2.2 MeVDT B
3/ 2/ 16.3( / ) exp[ / ] 0.01 D H N Dn n T m B T
4) 0.1 MeV ( 100 sec)T t
3
3
44
, +n
( He ) +n ( He+
H
e p)
e
H
D D T p
T D D3A little and He are left as cold ashes D
There is no stable nuclei for A=5,8. Mass 7 nuclei are produced a little.4
4
7
73
He +
He He
L
+
i
Be
T
7e
7e +LiB e
cf) 0.1 MeV ~ 109K
64 LHe i+ D
Time evolution of light elementsTime evolution of light elements
He4
D
Li7
Li6
He3
Observational Light Element Observational Light Element AbundancesAbundances
pY 0.2516 0.004 Peimbert,Lridiana,
Peimbert(2007)Izotov,Thuan, Stasinska (2007)
5D/ H (2.82 0.26) 10
Melendez,Ramirez(2004)
7sy10 st.log Li/ H 9.90 0 ( 0.35.09 )
O’Meara et al. (2006)
sy6
s7Li/ Li 0.046 0. ( 0.106022 ) Asplund et al(2006)
3He/ D 0.83 0.27 Geiss and Gloeckler (2003)
Fukugita, Kawasaki (2006)
SBBN
( / )Bn n
10
WMAP (6.225 0.160) 10 ( / )Bn n
Annihilation or decay during/after BBN epoch
Massive particle decaying/annihilating during/after BBN epoch produces high energy photons, hadrons, and neutrinos
Destruction/production/dilution of light elements
Severer constraints on the number density
Sato and Kobayashi (1977), Lindley (1984,1985), Khlopov and Linde (1984)
Ellis, Kim, Nanopoulos, (1984); Ellis, Nanopoulos, Sarkar (1985)
Kawasaki and Sato (1987)
Reno and Seckel (1988), Dimopoulos, Esmailzadeh, Hall, Starkman (1988)
Kawasaki, Moroi (1994), Sigl et al (95), Holtmann et al (97)
Jedamzik (2000), Kawasaki, Kohri, Moroi (2001), Kohri(2001), Cyburt, Ellis, Fields, Olive (2003)
Kawasaki, Kohri, Moroi(04), Jedamzik (06)
Electromagnetic mode
x
D + p + n
He3/D >~ O(1)
and / or e emissionDM DM
Hadronic modeHadronic mode
0
,
,
2
p pq q
n nDM DM W
Z
strongweakn p n pn p
Extraordinary inter-conversion reactions between n Extraordinary inter-conversion reactions between n
and pand p
Hadron induced exchange
/n p n pEven after freeze-out of n/p in SBBN
More He4, D, Li7 …
cf) 0n p 0p n
(( I) Early stage of BBN I) Early stage of BBN (T > 0.1MeV)Reno and Seckel (1988) Kohri
(2001)
(II) Late stage of BBN (T < 0.1MeV)Hadronic showers and “Hadro-dissociation” S. Dimopoulos et al. (1988)
fE E n (p)
Kawasaki, Kohri, Moroi (2004)
Non-thermal Li, Be Production by energetic nucleons or photons Dimopoulos et al (1989)
34 +X
N (or ) + HHe
Te
+ X
4 6T + He + [8.4 Li MeV]n
3 4 6 He + He + [7.0 L V]i Mep
4 4 *N (or ) + He He +X
4 4 6 7 7He +He Li, Li, Be + ...
3T, He4He
4He Energy loss
① T(He3) – He4 collision
② He4 – He4 collision
Jedamzik (2000)
Residual annihilation of DM even at around BBN epoch
• To fit the PAMELA and ATIC2/Fermi positron and electron signals ,
• At least it must emit charged leptons
• It might also emit hadrons
23 310 /v cm s
Electromagnetic cascade shower is induced
Hadronic cascade shower is induced
Hadron emission by residual annihilation in BBN epoch
Hisano, Kawasaki, Kohri, Moroi, Nakayama (09)
Charged-lepton (e+e-) emission by residual annihilation in BBN epoch
Hisano, Kawasaki, Kohri, Moroi, Nakayama (09)
Residual annihilation and CMB
• Energy injection affects the recombination history of the Universe
• Changing the ionization fraction affects CMB anisotropy very sensitively
Belicov and Hooper (09); Galli, Iocco, Bertone, Melchiorri (09); Huetsi, Hektor, Raidal (09) Cirelli, Iocco, Panci (09); Slatyer, Padmanabhan, Finkbeiner (09); Kanzaki, Kawasaki, Nakayama (09)
Constraint from CMB anisotropyKanzaki, Kawasaki, Nakayama (09)
What is the origin of Boost Factor (BF~103)
• BF = <σv>obs / <σv>canonical
• Local enhancement of DM density in astrophys
• Sommerfeld effectLight particle exchange annihilation for m < αmDM
(a kind of bound state formation, see also Hisano-Matsumoto-Nojiri (03) )
Non-perturbative effect
Enhancement of cross section <σv>~10-23 cm3/s without
breaking Unitarity and perturbation theory
Arkani-Hamed et al (08)
Velocity-dependent annihilation cross section?• Sommerfeld or Breit-Wigner enhancement
• The constraint from BBN and CMB is nontrivial
0~ with n=1,2,3,4, ...( / ) ...nvv c
See Zavala, Vogelsberger, White (09) for the constraint from μ-distortion of CMB
initial initial (f or kinetically-decoupling DM)~ ( / ) 1 v v T T 1/ 2
(f or kinetically-thermalized DM)~( / ) <<1 v T M
Hisano, Kawasaki, Kohri, Nakayama, arXiv:0810.1892 [hep-ph]
Gamma-ray signal from DM annihilation
Gamma-ray flux
5 5
2 2
b
Averaged over
ProfileNavarro-Frank-White (NFW): cusp structure
( 1 1.5)pr p Isothermal (iso): core structure
01/ [1 ( / ) ] ( 2)qr r q
Kawasaki, Kohri, Nakayama (09)
Gamma-ray signal from GC by DM annihilation
Results by Meade et al Meade, Papucci, Strumia, Volansky, arXiv:0905.0430
Gamma-ray obs by Fermi LAT Abdo et al, 0908.1171
22 60b
: ucleon-enhancement f actorM n
Kawasaki, Kohri, Nakayama (09)
Extragalactic diffuse Gamma-ray by DM annihilation
Neutrinos from galactic center expected by PAMELA/ATIC2
• Detecting up-going muons in Kamioka
• Annihilation (upper panel) and decay (lower panel)
• Direct-neutrino emission modes with NFW are excluded
Hisano, Kawasaki, Kohri, Nakayama (08)
Hisano, Nakayama Yang(09)
Astrophysical origin?
• Supernova Remnants (SNRs)
• Pulsar
• GRB
i. A local and old unknown SNR with ns<2 in radiative phase
ii. Statistically-known SNRs with (re)acceleration of secondary positron
Fujita, Kohri, Yamazaki, Ioka (09)
Ahlers, Mertsch, Sarkar (09)
See Kawanaka’s talk
See Kunihito Ioka, arXiv:0812.4851[astro-ph]
An old SNR near the Earth
• Proton was accelerated at a local SNR (<200 pc) in a dense gas cloud (n~50/cc) 106 years ago
• p-p collision produces pions electrons and positrons which propagated for 106 years
• The cloud had alrerady disappeared (see Loop I, Local Buble as its vestige)
• Antiproton was also produced
s s A,upp
photon index in radiative phase can be
n ~v / v 2
Fujita, Kohri, Yamazaki, Ioka, arXiv:0903.5298
• Source spectrum
• Spectrum
• Diffusion length
Fitted to Fermi by local SNR modelFujita, Kohri, Yamazaki, Ioka, arXiv:0903.5298
Fitted to Fermi by local SNR model
• Antiproton
Fujita, Kohri, Yamazaki, Ioka, arXiv:0903.5298
Fitted to Fermi by pp collision model
• B/C is also increasing?
Mertsch and Sarkar, arXiv:0905.3152v3
HEAO-3-C2
ATIC-2
CREAM
Summary
• Annihilation scenarios may have some problems to agree with BBN, CMB, and gamma-ray background
• It should be nontrivial to remove these discrepancies even if we adopt Sommerfeld or Breit-Wigner enhancement mechanism
• For astrophysical origin, so far we have not excluded a possible peculiar object such as a local and old SNR near the solar system.