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Dark Matter detection (2)Dark Matter detection (2)
CTICS 2012 CTICS 2012 Jan 25th, 2012
Sergio ColafrancescoSergio Colafrancesco Wits UniversityWits University - - DST/NRF SKA Research ChairDST/NRF SKA Research Chair INAF - OARINAF - OAR EmailEmail: [email protected] [email protected]
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OutlineMulti-epoch
The Dark Matter TimelineThe present
Multi-Scale + M3
Galactic centerGalactic structuresGalaxy Clusters
The FutureThe DM search challenge
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Viable DM candidates: signalsNeutralinos
Radiative decay: line
νs → να + γ
Sterile ν’s
[ ]
×
⟩⟨∝
νχ
σρχ
ddEEf
VM
rD
F
ann
DM
L
);(
)(12
2
2
[ ]
×
⟩Γ⟨∝
ν
ρ
γ ddEME
Mr
DF
v
radv
DM
L
)(
)(12
DM annihilation flux DM decay flux
Astro physics
Particle physics
Annihilation
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Viable DM candidates: signalsNeutralinos
Radiative decay: line
νs → να + γ
Ms
Mχ
Inverse Compton scattering
Synchr.
Bremsstrahlung
π0
Sterile ν’s
Annihilation
Particle physics
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SUSY neutralino DM
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Gamma raysbremsstrahlung
ICS
χ
χπ±
π0 γ+γ
Gamma rays (π0 decay)
pe±
SZ effectICS
Radio emissionSynchrotron
B
e±e±
γCMB
p
e±γCMB
X-raysbremsstrahlung
ICS
High frequency
Hadronic
Hadronic
processes
processes
Low frequency
Leptonic processes
Leptonic processes
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Covering the whole e.m. spectrum
SynchrotronSZ
Effe
ct
ICS
Brem.+ICS+π 0
Brem.+ICS
ICS
χχannihilation
products
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Leptons: e± equilibrium spectrum
[ ] [ ] ),(),()(),()(),( rEQrEnEbE
rEnEDtrEn
eeeee =
∂∂−∇∇−
∂∂
Production Equilibrium
),( rEQe ),( rEne
Diffusion E lossesγγ −= BEDED 0)( bremCoulsyncICe bbbbEb +++=)(
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Solution: complete
)()(
4)(exp
4)(exp)()1(
]4[1ˆ
2
222
0'
2
2/1 rnrnrrrr
rrrrdG nn
R
nn
nh
χ
χ
λλλπ′
∆+′
−−
∆
−′−
′′−∆
= ∫∑∞+
− ∞=
∫ ′−′=χ
λλM
Eee rEQrGEd
EbrEn ),(),(ˆ
)(1),(
NFW04
[Colafrancesco, Profumo & Ullio 2006-2007]
Galaxy clusters
Galaxies
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Energy losses vs. Diffusion
B increase nth decrease
Rh decrease
),,( thloss nBEb
E=τ )(
2
EDRh
D =τ
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Solution: qualitative[ ]
lossD
D
diffusionsource
sourcelossee VV
VrEQrEnττ
ττ+
⋅+
⋅= ),(),(
[ ]lossee rEQrEn τ),(),( = [ ]loss
D
diffusion
sourcelossee V
VrEQrEnτττ ⋅⋅= ),(),(
VD
VsVs
VD
τ loss « τ D τ loss » τ D
Galaxy clusters Galaxies
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Neutralino DM: SED
_bb
Mχ=40 GeV
Synch. ICS on CMB
Fermi
π0 decay
Prompthadrons
Secondary productsleptons
s8106.2 −⋅≈±πτ s17104.80
−⋅≈π
τ
. .
10-30-31 ←SKA (1GHz)
CTA
NuSTAR
DUALComa
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DM - Astrophysical Laboratories
Leo I dSph
NGC3338
Bullet cluster
GC
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The Galactic Center
Radio 90 cm
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The Galactic Center
Mid-IR
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The Galactic Center
X-rays 1-8 keV
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The Galactic Center
Multi-ν
Galactic center region across the spectrum: red: radio 90 cm (VLA); green: mid-infrared; blue: X-ray (1-8 keV; Chandra ACIS-I)
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The Galactic Center: a close up
Galactic Center (Survey) Multiwavelength Close-Up A multiwavelength close-up of the recent massive star-forming region near the Galactic center. The color image, plotted also in standard Galactic coordinates, is a composite of 20-cm radio continuum (red); 25-µm mid-infrared (green); and 6.4-keV line emission (blue).
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Galactic Center demography
EGRET source
Central Black Hole
SNR Sgr A East non-thermal filaments (radio)X-ray source
Fermi (1GeV)
Crowded, active environment
HESS CTA
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The GC region DM challenge
Gondolo 1998Gondolo & Silk 1999…Cesarini et al. 2003 …De Boer et al. 2005 …Hooper et al. 2008…Borriello et al. 2008Regis & Ullio 2008Crocker et al. 2010
Sgr-A SED in quiescent radio + X-ray stage [Regis & Ullio 2008]
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The GC region DM challenge: limitsConstraints from radio + γ-rays• Radio: constrain to ~ GeV-TeV mass• γ-rays: constrain to ≤ GeV mass• ν’s : constrain to > 10 TeV mass
Borriello et al. 2008
Radio + EGRET
Radio + HESS [Crocker et al. 2010]
[Regis & Ullio 2008]
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The GC region DM challenge: limitsFermi-LAT results on the diffuse γ-ray emission improves DM limits → by a factor ~ 20-50
[Abazajian et al. 2010]Caveats• modelling of diffuse foregrounds (Galactic, Extra-Galactic)• unresolved point-like sources (PSR, MCs, AGNs, Starburst gal., Clusters, GRBs,..)• data analysis techniques (Likelihood vs. photon counts)
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The GC region DM challenge: HESSSearch for a DM annihilation signal from the Galactic Center halo with H.E.S.S. (arXiv:1103.3266v)
Thermal Dark Matter
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The GC region DM challengeStrongest constraints from SKA + CTA• Radio: constrain to ~ GeV-TeV mass• γ-rays: constrain to ~ GeV-TeV mass• ν’s : constrain to > 10 TeV mass
VLA
Radio + EGRET
Radio + HESS
-28
-29SKA P2 + CTASKA CTA
SKA P1
MeerKAT+HESS
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The GC region DM challenge: uncertaintiesB-field at GC• from 4 to 1000 µG• > 50µG (radio + γ-rays) [Crocker et al. 2010]
Diffusion
DM density profile DM dynamics at GCDM vs. BH Astrophysical sourcesStationary & Transient [Regis & Ullio 2008]
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The GC HazeRadio emission due to secondary e± is spatially extended (ν-dependent)
Radio halo (haze) RH size decreases with increasing ν
ICS emission due to secondary e± is spatially extended (ν-dependent)
The angular size for the equilibrium n. density of high-E e± is much broader than the γ-ray flux from π0 decays
IC halo (haze) ICH size decreases with increasing ν
π0 halo (haze) = DM sourceπH size smaller than RH / ICH size
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WMAP vs. Fermi haze
Cosmic ray electrons interacting with the Galactic magnetic field
cosmic ray electrons interacting with the ISRF to produce ICS
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GC hazes: puzzles or certainties
DM predictionGalprop
Fermi data(Dobler et al. 2009)
Dark Matter
- DM (W±,bb) is not the origin of Fermi haze- DM (e±) can fit the Fermi haze with a boost factor ~ 100 → multi-ν problems
[Malyshev et al. 2010]
ms Pulsars
- 50 % energy conversion in e±
- 30,000 msP in GC- msP not resolved in radio and gamma. → Haze of unresolved point-like sources
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msP around the GC
[Wang 2005]
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Galaxy DM sub-halos: radio emission
Radio emission from DM clumps - Strong diffusion effects - Degeneracy of ne and B-field - B-field uncertainty
16 0.16 1.610-4 1.610-7 mJy
• Angular power spectrum Cll(l+1) →→ typical scale: λmax(E,B) • Break ne – B degeneracy →→ SZE (@30 GHz) observations
DM
VLA obs.
[Baltz & Wai 2004, …Borriello et al. 2008… Colafrancesco et al. 2012]
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Galaxy DM sub-halos: γ-rays
[DM simulation Kuhlen et al. arXiv:0704.0944]
Possibility to detect single or a population of DM clumps via their π0 decay γ-ray emission.
CAVEATSGalactic diffuse emission plus its fluctuations (spatial + spectral)Foreground removal- Galaxy- Blazars- Galaxies- Starburst galaxies- Galaxy clusters- Pulsars- SNRs- MCsVariabilitySpectral separationClustering properties …
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The Gamma-ray sky
Blazars
DM
multipole1 10 102
l(l+1
)Cl/2
π
103
Fermi all-sky survey Angular power spectrum
Variability
[Ando 2005]
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Dwarf Spheroidal Galaxies: DM halosSmall-size, dynamically un-relaxed… but few good cases !
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The darkest galaxies in the universe
Segue 1 dwarf galaxy → M/LV ~ 3400 M/L
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Dwarf galaxies & DM: Fermi
[Fermi-LAT collaboration 2010]Assumptions- NFW profile- No boost factor (no substructures)
MSUGRA MSSM
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The Dwarf Galaxies DM challenge[ ]
lossD
D
diffusionsource
sourcelossee VV
VrEQrEnττ
ττ+
⋅+
⋅= ),(),(
VD
τ loss » τ D
Vs
[ ]loss
D
diffusion
sourcelossee V
VrEQrEnτττ ⋅⋅= ),(),(
Iν
r
Sub-galactic size systems- R ~ kpc- No gas- Little dust- No Crs- 1 (or 2) stellar populations- M/L ~ 500 - 3500
+ Ideal systems to probe DM+ Clean multi-ν features
but…
- Strong diffusion effects- Low signals
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Dwarf Sph. galaxies & DM constraintsVD
VS
22 ),,()(
χ
σνν
Mv
rEnDBI eee ⊗⊗∝
γ)/(0 BEDD ee =
Spectrum BrightnessB χ
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ATCA → MeerKAT → SKA
ATCAMeerKAT
SKA
ATCA MeerKATSKA
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Dark Matter search @ radio
SKA-P1MeerKAT
ATCA 121hr
Segue-3 Carina
Fermi 2yr
121.5 hr @ ATCA to observe 6 dwarf galaxies
[S.C. et al. 2011]
Constraints on DM parameter space
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Expectations: the HXR range
σV=4 10-28 cm3/s DracoσV=4 10-28 cm3/s
Normalization fixed by the lack ofdetection in ATCA (F1.3GHz < 10µJy)
ATCA
0.1µG
1µG no diffdiff
π0
ICSSynch
HXR and radio profiles are differentHXR and –ray profiles are similar
NuSTAR DUAL
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SZE from DM annihilation
SKA-P2 (0.1-45 GHz) MeerKAT (0.7-30 GHz)• Measure radio (low ν) & ICS emission (high ν) from DM halos• Disentangle electron population and B-field → Fradio/FICS = UB/UCMB
• DM halo Cosmology: “purified” DM halo
Inverse Compton Scatteringof CMB photons
by secondary DM electrons ∫ ⋅⋅≈∆
eCMB
CMB PdMxgTT
);( χ
DM halo
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XMM
SKA P1
SKA P2
CTA
Gamma-ray Radio
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Galaxy clusters: the largest DM labs.
Large-size, dynamically stable… but co-spatial DM+baryon … except one!
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The cluster 1ES0657-556
DM clump A)M = 1015 M
Gas clump A)T = 14 keV
Gas clump B)T = 6 keV
DM clump B)M = 6 1013 M
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Normal clusters of galaxies
Coma A2163
A2255 A2319
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Multi-ν expectations from DM
[Colafrancesco, Profumo & Ullio 2006]
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Neutralino DM: ICS of CMB (SZE)
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The SZ effect
thermal NR e-
relativistic e- 2
34 γ
νν ≈∆
24cm
kT
e
e≈∆ν
ν
I0(x) I(x)
Irel(x)
Thermal
Relativistic
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SZE in DM halos
SZth
SZwarm
SZrel
SZDM
A structure with:
• Hot gas• Warm gas• Rel. Plasma• DM• (Vr ≈ 0)
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SZE in DM halos
SZth
SZwarm
SZDM
A structure with:
• Hot gas• Warm gas• • DM• (Vr ≈ 0)
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SZE in DM halos
SZDM
A structure with:
• • • • DM• (Vr ≈ 0)
[Colafrancesco 2004, A&A, 422, L23]
Pure DM halo
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The cluster 1ES0657-556
DM clump A)M = 1015 M
Gas clump A)T = 14 keV
Gas clump B)T = 6 keV
DM clump B)M = 6 1013 M
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SZE in 1ES0657-556
gas SZE
DM SZE
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Isolating SZDM at ∼223 GHzFr
eque
ncy
(M
χ= 2
0 G
eV)
Neu
tral
ino
mas
s (
ν=22
3 G
Hz)
[Colafrancesco et al. 2007]
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Neutralino DM: radio emission
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Clusters of galaxies
Integrated spectrum (30 MHz-5 GHz)
sub-halos
Coma
Brightness distribution (@ 1.4 GHz)
vrEnDBS eee σνν ),,()( 2⊗⊗∝vrEnDBI eee σνν ),,()( 2⊗⊗∝ B
χ
[Colafrancesco, Profumo & Ullio 2006]
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Galaxy clusters: DM challengeGalaxy clusters: DM challenge
DM only CRs only
Dark MatterBaryons + Cosmic Rays
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Neutralino DM: X-ray emission
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A Dark TemptationExplain HXR in cluster as DM annihilation signals
OPHIUCHUS
More than 20 clusters with Hard X-ray excessat E> 20 keV (Swift-BAT data, BeppoSAX data)
Equally fit with:- Two temperature (thermal) plasma- Thermal plasma + non-thermal power-law
AGN emission or ICS from DM / CR interaction
A3627
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Hard X-ray excess
[Colafrancesco & Marchegiani 2009]
Consequence
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DM & heating
ICSHeating
[Colafrancesco & Marchegiani 2009]
DM models that fit the HXR flux of galaxy clusters produce also an excess heating of the gas.
Th. Brem. cooling
DM annih. heating
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Dark temptations never go away...
[Jeltema & Profumo arXiv:1108.1407]
Normalized to F(E> 0.1 GeV) Possible detection for texp> 4Msec
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HXR – Gamma vs. HXR - Radio
σV=7·10-21 cm3/s
5µG
HXR – Radio correlation provides stronger constraints on DM(MeerKAT/SKA vs. NuSTAR/DUAL combined obs. @ Wits University)
Normalized to F(ν=1.4GHz)With known B=5µG
1µG
0.2µG
σV=10-25 cm3/s
GeV experiments are far fromDM signal detections
5µG
1µG
0.2µG
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DM signal profiles: HXR-Radio-gamma
A2163σV=7·10-21 cm3/s
Ssynch(1.4 GHz)B=5 µG
SICS(50 keV)
Sπ0(1 GeV)
NuSTAR DUAL
σV=10-25 cm3/s Hydra
Ssynch(1.4 GHz)B=1 µG
SICS(50 keV)
Sπ0(1 GeV)
NuSTAR DUAL
There is a spatial signature of DM signals visible in the HXRs
Clear HXR-radio correlations at large angular scales (> 1 arcmin)
No clear HXR-gamma correlation at all angular scales
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DM & γ-rays: Fermi limitsNeutralino upper limits from 2 recent preprints:Q.Yuan et al. 2010 (arXiv:1002.0197)Fermi-LAT collaboration 2010 (arXiv:1002.2239)
… but very optimistic upper limits (no CRs, no AGNs, no gal., …)
no substructures substructures
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DM models & non-thermal phenomenaComa Coma Coma
CTA CTA CTA
SKA SKA SKA
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Astrophysics vs. Underground DM search
[arXiv:1109.0702]
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CRs (and γ-rays) from Perseus RGs
Chandra FERMI
MAGICSHALOM
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Modelling the Perseus cluster
NGC1275Blazarcore
RG (3C84)Mini RHSy 1.5Blazar
[Colafrancesco et al. 2010]]
1
2 3
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DM @ γ-rays: disentangling CRs, AGN, DM
[Colafrancesco & Marchegiani 2010][Abdo et al.+S.C. 2009]
Perseus + NGC1275
DM
heating
Possibility to detect γ-rays from Perseus• in low-states of the central AGN• in the outer parts of the cluster (>780kpc)
high
low
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Overall contraints to DM scenarios
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Exploring DM universes
DirectDetectionTechniques
p-χ cross-section
Neutralino χ mass
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Exploring DM universes
DirectDetectionTechniques
p-χ cross-section
Neutralino χ mass
9 orders of mag. in
direct detectioncross-section
usually not shown
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Exploring DM universesDirectDetection
Indirect DetectionFermiCTASKA
Unde
rgro
und d
etecto
rs
Astrophysics
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Exploring DM universesDirectDetection
Indirect Detection
FermiCTASKA
SKA
LHC + AstrophysicsDM detectors + Astrophysics
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Sterile neutrino DM
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Sterile neutrino DM: lineHot gasDark Matter
νs → να + γ
expectation
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Sterile neutrinos: limits
[Watson et al. 2006 (astro-ph/0605424)]
Excluded
[Colafrancesco 2007]
Bullet cluster
Excl
ude
d by
Ly-
α
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Coma constraints from 20-80 keV emission
[Yuksel et al. 2007][Colafrancesco 2007]
NHXMNEXTnuStar
DUAL
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Sterile neutrinos and GC lines
Fact:Excess of the intensity in the 8.7 keV line (at the energy of the FeXXVI Lyγ line) in the spectrum of the Galactic Center observed by the Suzaku X-ray mission.Not easily explained by standard ionization and recombination processes.
Proposed issue:the origin of this excess is via decays of sterile neutrinos with m ~ 17.4 keV and mixing angle sin2(2θ) =(4.1±2.2)×10−12
[Prokhorov & Silk 2010]
But: - possible non-standard ionization and recombination processes
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Other DM options
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Neutralino DM: particles
e- e+
p p-
…
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Pamela and ATIC
Astrophysical expectation (secondary production)
Rapid climb above 10 GeV indicates the presence of a primary source of cosmic ray positrons!
Charge-dependent solarmodulation important below 5-10 GeV
PamelaATIC
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Fermi Collaboration (2009)
HESS and Fermi
[Zhang, Cheng (2001); Hooper et al. (2008)Yuksel et al. (2008); Profumo (2008)Fermi LAT Collaboration (2009)]
Astrophysics can explain PAMELA:- Pulsars- SN remnants- Diffusion effects
Fermi and HESS do not confirm ATIC:→ consistent with bkgd. expectations
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OutlineMulti-epoch
The Dark Matter TimelineThe present
Multi-ScaleDM search at various astronomical scales
• Galactic center• Galactic structures• Galaxy Clusters
The FutureThe DM search challenge
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What do we really know about dark matter? All solid evidence is gravitationalAlso solid evidence against strong and EM interactions
Neutralino DM: Hidden DM !?!Experimental Frustration
• No direct evidence (DAMA vs. other underground experiments)• No photonic signals (only upper limits from Multi-ν analysis)• No particle signal (Pamela → ATIC: embarassing results)
Pause
@
Return
Esc
The anomalies (DAMA, PAMELA, ATIC, …) are not easily explained by canonical WIMPs → go beyond MSSM WIMP model
A reasonable 1st order guess: Dark Matter has no SM gauge interactions, i.e., it is hidden [Kobsarev, Okun, Pomeranchuk (1966); many others] [Feng et al. 2009]What one seemingly loses:
Connection to central problems of particle physicsNon-gravitational signalsThe WIMP miracle
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• Astrophysical (e.m.) search is a crucial probe for the DM nature.• Multi3-4 search in optimal astrophysical laboratories is the key issue but is challenging.• The temptation to explain every astrophysical anomaly as due to DM is pushing DM search towards a fundamentalist approach rather than to search for the its fundamental nature.• The possible lack of DM evidence should be considered positively as the necessity to explore in further details the basic laws of the Universe → Gravity field modification on cosmological scales…
… some conclusions
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DM … or Modified Gravity !?!
J. Moffat says, "If the multi-billion dollar laboratory experiments now underway succeed in directly detecting dark matter, then I will be happy to see Einstein and Newtonian gravity retained. However, if dark matter is not detected and we have to conclude that it does not exist, then Einstein and Newtonian gravity must be modified to fit the extensive amount of astronomical and cosmological data, such as the bullet cluster, that cannot otherwise be explained.
Dark Matter
Could MOG explain also the dynamics of the bullet cluster ?
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DM
G
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THANKS
for your attention !