1

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: Sergio.Colafrancesco@wits.ac.za Sergio.Colafrancesco@oa-roma.inaf.it

2

OutlineMulti-epoch

The Dark Matter TimelineThe present

Multi-Scale + M3

Galactic centerGalactic structuresGalaxy Clusters

The FutureThe DM search challenge

3

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

4

Viable DM candidates: signalsNeutralinos

Radiative decay: line

νs → να + γ

Ms

Mχ

Inverse Compton scattering

Synchr.

Bremsstrahlung

π0

Sterile ν’s

Annihilation

Particle physics

5

SUSY neutralino DM

6

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

7

Covering the whole e.m. spectrum

SynchrotronSZ

Effe

ct

ICS

Brem.+ICS+π 0

Brem.+ICS

ICS

χχannihilation

products

8

Leptons: e± equilibrium spectrum

[ ] [ ] ),(),()(),()(),( rEQrEnEbE

rEnEDtrEn

eeeee =

∂∂−∇∇−

∂∂

Production Equilibrium

),( rEQe ),( rEne

Diffusion E lossesγγ −= BEDED 0)( bremCoulsyncICe bbbbEb +++=)(

9

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

10

Energy losses vs. Diffusion

B increase nth decrease

Rh decrease

),,( thloss nBEb

E=τ )(

2

EDRh

D =τ

11

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

12

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]

55

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]

57

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

81

Other DM options

82

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

84

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

85

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

86

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

90

THANKS

for your attention !