1. CTICS 2012 Jan 25th, 2012
Dark Matter detection (2)
Sergio Colafrancesco
Wits University - DST/NRF SKA Research Chair
INAF - OAR
Email: Sergio.Colafrancesco@wits.ac.za
Email
Sergio.Colafrancesco@oa-roma.inaf.it
1

2. Outline
Multi-epoch
The Dark Matter Timeline
The present
Multi-Scale + M3
Galactic center
Galactic structures
Galaxy Clusters
The Future
The DM search challenge
2

3. Viable DM candidates: signals
Neutralinos Sterile ν’s
Annihilation Radiative decay: line
νs → να + γ
DM annihilation flux DM decay flux
1 ρ DM ( r )
2
1 ρ DM ( r )
F ∝ 2 2
〈σ V 〉 Astro physics F ∝ 2
〈 Γ rad 〉
DL Mχ DL Mv
 dE 
× [ f ann ( E ; χ )]  Particle physics [ ]
 dE 
× Eγ ( M v )  
 dν   dν 
3

4. Viable DM candidates: signals
Neutralinos Sterile ν’s
Annihilation Radiative decay: line
νs → να + γ
Ms
Inverse Compton scattering
π0 Mχ
Synchr.
Particle physics
Bremsstrahlung
4

5. SUSY neutralino DM
5

6. High frequency
X-rays p
bremsstrahlung
Ha oces
Ha ces
ICS
prr
po
drr se
γ+γ
d o se
γCMB e± π0
on s
niic s
c
Le
Le
π± χ
pt
pt
on
on
χ p Gamma rays
iic
e±
cp
(π0 decay)
e±
pr
e±
ro
γCMB
oc
cees
Gamma rays
ssse
bremsstrahlung
es
Low frequency B
s
ICS
Radio emission SZ effect
ICS
Synchrotron 6

7. Covering the whole e.m. spectrum
χχ
annihilation
products
Br Br
on e e m
t
tr
fec
o m .+
hr .+ IC
Ef
IC S
c IC S+
IC
yn S π0
SZ
S
S
7

8. Leptons: e± equilibrium spectrum
∂ ne ( E , r ) ∂
− ∇ [ D( E )∇ ne ( E , r )] − [ be ( E )ne ( E , r )] = Qe ( E , r )
∂t ∂E
Production Equilibrium
Qe ( E , r ) ne ( E , r )
Diffusion E losses
D( E ) = D0 E γ B − γ be ( E ) = bIC + bsync + bCoul + bbrem
8

9. Solution: complete
Mχ
1 ˆ
ne ( E , r ) =
b( E ) ∫
E
dE ′G (r , λ − λ ′ )Qe ( E , r )
NFW04
Galaxy clusters
Galaxies
(r ′ ) 2   (rn′ + r ) 2   nχ (r ′ )
Rh 2
1 +∞
 (r ′ − rn ) 2 
ˆ=
G
[4π ∆ λ ]1/ 2
∑− ∞ (− 1) n ∫ dr ′ '  exp −
rn r   4∆ λ 
 − exp −
   2
4 ∆ λ   nχ ( r )
n= 0   
[Colafrancesco, Profumo & Ullio 2006-2007] 9

10. Energy losses vs. Diffusion
2
E Rh
τ loss = τ D =
b( E , B, nth ) D( E )
B increase nth decrease
Rh decrease
10

11. Solution: qualitative
Vsource τD
ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
Vsource + Vdiffusion τ D + τ loss
VD VD
Vs Vs
τ loss « τ D τ loss » τ D
Vsource τ D
ne ( E , r ) = [ Qe ( E , r )τ loss ] ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
Vdiffusion τ loss
Galaxy clusters Galaxies 11

12. Neutralino DM: SED
−8
τ π ± ≈ 2.6 ⋅ 10 s Synch. ICS on CMB π0 decay τ 0 ≈ 8.4 ⋅ 10− 17 s
π
Coma DUAL
Mχ=40 GeV Fermi
_
bb
CTA
NuSTAR
Secondary products Prompt
leptons hadrons
.
.
10-30-31 ←SKA (1GHz) 12

13. DM - Astrophysical Laboratories
GC
Leo I dSph
NGC3338
Bullet cluster
13

14. The Galactic Center
Radio 90 cm
14

15. The Galactic Center
Mid-IR
15

16. The Galactic Center
X-rays 1-8 keV
16

17. 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)
17

18. 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). 18

19. Galactic Center demography
Crowded, active environment
HESS CTA
Fermi (1GeV)
EGRET source
Central Black Hole
X-ray source SNR Sgr A East non-thermal filaments (radio)
19

20. The GC region DM challenge
Gondolo 1998
Gondolo & Silk 1999
…
Cesarini et al. 2003
…
De Boer et al. 2005
…
Hooper et al. 2008
…
Borriello et al. 2008
Regis & Ullio 2008
Crocker et al. 2010
Sgr-A SED in quiescent radio + X-ray stage
[Regis & Ullio 2008]
20

21. The GC region DM challenge: limits
Constraints 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
[Crocker et al. 2010]
Radio + HESS
[Regis & Ullio 2008]
21

22. The GC region DM challenge: limits
Fermi-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) 22

23. The GC region DM challenge: HESS
Search for a DM annihilation signal
from the Galactic Center halo with
H.E.S.S. (arXiv:1103.3266v)
Thermal Dark Matter
23

24. The GC region DM challenge
Strongest constraints from SKA + CTA
• Radio: constrain to ~ GeV-TeV mass
• γ-rays: constrain to ~ GeV-TeV mass VLA
• ν’s : constrain to > 10 TeV mass
T
G RE
io +E
Rad ES
S
o +H
R adi
S
H ES
+
K AT
M eer
SKA CTA
P1 C TA
-28 A +
SK P2
A
SK
-29 24

25. The GC region DM challenge: uncertainties
B-field at GC
• from 4 to 1000 µG
• > 50µG (radio + γ-rays)
[Crocker et al. 2010]
Diffusion
DM density profile
DM dynamics at GC
DM vs. BH
Astrophysical sources
[Regis & Ullio 2008]
Stationary & Transient
25

26. The GC Haze
Radio 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)
IC halo (haze)
ICH size decreases with increasing ν
The angular size for the equilibrium n.
density of high-E e± is much broader
than the γ-ray flux from π0 decays
π0 halo (haze) = DM source
πH size smaller than RH / ICH size 26

27. WMAP vs. Fermi haze
Cosmic ray electrons interacting
with the Galactic magnetic field
cosmic ray electrons interacting
with the ISRF to produce ICS
27

28. GC hazes: puzzles or certainties
Dark Matter
- DM (W±,bb) is not the
origin of Fermi haze
- DM (e±) can fit the
Fermi haze with a
boost factor ~ 100 DM prediction Fermi data
→ multi-ν problems Galprop (Dobler et al. 2009)
ms Pulsars
- 50 % energy
conversion in e±
- 30,000 msP in GC
- msP not resolved
in radio and gamma.
→ Haze of unresolved [Malyshev et al. 2010]
point-like sources 28

29. msP around the GC
[Wang 2005]
29

30. Galaxy DM sub-halos: radio emission
VLA obs.
DM
16 0.16 1.610-4 1.610-7 mJy
Radio emission from DM clumps • Angular power spectrum Cll(l+1)
- Strong diffusion effects → typical scale: λmax(E,B)
- Degeneracy of ne and B-field • Break ne – B degeneracy
- B-field uncertainty → SZE (@30 GHz) observations
[Baltz & Wai 2004, …Borriello et al. 2008… Colafrancesco et al. 2012] 30

31. Galaxy DM sub-halos: γ-rays
Possibility to detect single or a population of CAVEATS
DM clumps via their π0 decay γ-ray emission. Galactic diffuse emission
plus its fluctuations
(spatial + spectral)
Foreground removal
- Galaxy
- Blazars
- Galaxies
- Starburst galaxies
- Galaxy clusters
- Pulsars
- SNRs
- MCs
Variability
Spectral separation
[DM simulation Kuhlen et al. arXiv:0704.0944] Clustering properties
…
31

32. The Gamma-ray sky
Fermi all-sky survey Angular power spectrum
Blazars
[Ando 2005]
Variability
l(l+1)Cl/2π
DM
1 10 102 103
multipole 32

33. Dwarf Spheroidal Galaxies: DM halos
Small-size, dynamically un-relaxed… but few good cases !
33

34. The darkest galaxies in the universe
Segue 1 dwarf galaxy → M/LV ~ 3400 M/L
34

35. Dwarf galaxies & DM: Fermi
MSUGRA MSSM
[Fermi-LAT collaboration 2010]
Assumptions
- NFW profile
- No boost factor (no substructures)
35

36. The Dwarf Galaxies DM challenge
Vsource τD
Sub-galactic size systems ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
- R ~ kpc Vsource + Vdiffusion τ D + τ loss
- No gas
- Little dust VD
- No Crs
- 1 (or 2) stellar populations Vs
- M/L ~ 500 - 3500
τ loss » τ D
+ Ideal systems to probe DM
Vsource τ D
+ Clean multi-ν features ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
Vdiffusion τ loss
but…
Iν
- Strong diffusion effects
- Low signals r
36

37. Dwarf Sph. galaxies & DM constraints
σv VD
I (ν ) ∝ B ⊗ De ⊗ n ( Ee ,ν , r ) 2
2
e
Mχ
VS
γ
De = D0 ( Ee / B)
Spectrum
B χ Brightness
37

38. ATCA → MeerKAT → SKA
ATCA
MeerKAT
SKA
ATCA MeerKAT
SKA
38

39. Dark Matter search @ radio
121.5 hr @ ATCA
to observe 6 dwarf galaxies
[S.C. et al. 2011]
Constraints on DM parameter space
Segue-3 Carina
Fermi 2yr
ATCA 121hr
MeerKAT
SKA-P1
39

40. Expectations: the HXR range
Normalization fixed by the lack of HXR and radio profiles are different
detection in ATCA (F1.3GHz < 10µJy) HXR and –ray profiles are similar
σV=4 10-28 cm3/s
Draco
σV=4 10-28 cm3/s
0.1µG π0
ICS
Synch
1µG no diff
diff
ATCA
NuSTAR DUAL
40

41. SZE from DM annihilation
Inverse Compton Scattering
∆ TCMB
of CMB photons ≈ g ( x; M χ ) ⋅ ∫ d ⋅ Pe
by secondary DM electrons TCMB
DM halo
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
41
•

42. Gamma-ray Radio
XMM
CTA SKA P1
SKA P2
42

43. Galaxy clusters: the largest DM labs.
Large-size, dynamically stable… but co-spatial DM+baryon
… except one! 43

44. The cluster 1ES0657-556
Gas clump A) Gas clump B)
T = 14 keV T = 6 keV
DM clump B)
M = 6 1013 M
DM clump A)
M = 1015 M
44

45. Normal clusters of galaxies
Coma A2163
A2255
A2319
45

46. Multi-ν expectations from DM
[Colafrancesco, Profumo & Ullio 2006]
46

47. Neutralino DM: ICS of CMB (SZE)
47

48. The SZ effect
Thermal
I0(x) I(x)
Irel(x)
Relativistic
∆ν kT
thermal NR e - ≈ 4 e2
ν me c
∆ν 4
relativistic e- ≈ γ 2
ν 3
48

49. SZE in DM halos
SZth
A structure with:
• Hot gas
SZwarm
• Warm gas
• Rel. Plasma
• DM
• (Vr ≈ 0)
SZrel
SZDM
49

50. SZE in DM halos
SZth
A structure with:
• Hot gas
SZwarm
• Warm gas
•
• DM
• (Vr ≈ 0)
SZDM
50

51. SZE in DM halos [Colafrancesco 2004, A&A, 422, L23]
A structure with:
•
•
•
• DM
• (Vr ≈ 0)
SZDM
Pure DM halo
51

52. The cluster 1ES0657-556
Gas clump A) Gas clump B)
T = 14 keV T = 6 keV
DM clump B)
M = 6 1013 M
DM clump A)
M = 1015 M
52

53. SZE in 1ES0657-556
gas SZE
DM SZE
53

54. Isolating SZDM at ∼223 GHz [Colafrancesco et al. 2007]
Neutralino mass (ν=223 GHz)
Frequency (Mχ= 20 GeV)
54

55. Neutralino DM: radio emission
55

56. Clusters of galaxies
Integrated spectrum Brightness distribution
(30 MHz-5 GHz) (@ 1.4 GHz)
I (ν ) ∝ B ⊗ De ⊗ ne2 ( Ee ,ν , r ) σ v B S (ν ) ∝ B ⊗ De ⊗ ne2 ( Ee ,ν , r ) σ v
Coma
χ su
b-h
alo
s
[Colafrancesco, Profumo & Ullio 2006] 56

57. Galaxy clusters: DM challenge
Baryons + Cosmic Rays
Dark Matter
DM only CRs only
57

58. Neutralino DM: X-ray emission
58

59. A Dark Temptation
Explain HXR in cluster as DM annihilation signals
A3627 More than 20 clusters with Hard X-ray excess
at 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
OPHIUCHUS
59

60. Hard X-ray excess Consequence
[Colafrancesco & Marchegiani 2009] 60

61. DM & heating
DM models that fit the HXR flux
of galaxy clusters produce also
an excess heating of the gas.
Heating ICS
DM annih. heating
Th. Brem. cooling
[Colafrancesco & Marchegiani 2009] 61

62. Dark temptations never go away...
Normalized to F(E> 0.1 GeV) Possible detection for texp> 4Msec
[Jeltema & Profumo arXiv:1108.1407]
62

63. HXR – Gamma vs. HXR - Radio
Normalized to F(ν=1.4GHz) GeV experiments are far from
With known B=5µG DM signal detections
σV=7·10-21 cm3/s σV=10-25 cm3/s
5µG
5µG
1µG
1µG
0.2µG
0.2µG
HXR – Radio correlation provides stronger constraints on DM
(MeerKAT/SKA vs. NuSTAR/DUAL combined obs. @ Wits University)
63

64. DM signal profiles: HXR-Radio-gamma
A2163 Hydra
σV=7·10-21 cm3/s σV=10-25 cm3/s
Sπ0(1 GeV) Sπ0(1 GeV)
SICS(50 keV) Ssynch(1.4 GHz) SICS(50 keV)
Ssynch(1.4 GHz)
B=5 µG B=1 µG
NuSTAR DUAL 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 64

65. DM & γ-rays: Fermi limits
Neutralino upper limits from 2 recent preprints:
Q.Yuan et al. 2010 (arXiv:1002.0197)
Fermi-LAT collaboration 2010 (arXiv:1002.2239)
no substructures substructures
… but very optimistic upper limits (no CRs, no AGNs, no gal.,65…)

66. DM models & non-thermal phenomena
Coma Coma Coma
CTA CTA CTA
SKA SKA SKA
66

67. Astrophysics vs. Underground DM search
[arXiv:1109.0702]
67

68. CRs (and γ-rays) from Perseus RGs
Chandra FERMI
SHALOM MAGIC
68

69. Modelling the Perseus cluster
RG (3C84)
Mini RH
Sy 1.5 NGC1275
Blazar Blazar
core
1
2 3
[Colafrancesco et al. 2010]] 69

70. DM @ γ-rays: disentangling CRs, AGN, DM
Possibility to detect γ-rays from Perseus
• in low-states of the central AGN
• in the outer parts of the cluster (>780kpc)
Perseus + NGC1275
[Colafrancesco & Marchegiani 2010]
[Abdo et al.+S.C. 2009]
heating high
DM
low
70

71. Overall contraints to DM scenarios
71

72. Exploring DM universes
Direct
Detection
Techniques
p-χ cross-section
Neutralino χ mass
72

73. Exploring DM universes
Direct
Detection
Techniques
p-χ cross-section
9 orders
of mag. in
direct detection
cross-section
usually
not shown
Neutralino χ mass 73

74. Exploring DM universes
Direct
Detection
Underground detectors
SKA CTA Fermi Astrophysics
Indirect Detection
74

75. Exploring DM universes
Direct
DM detectors + Astrophysics LHC + Astrophysics
Detection
SKA
SKA CTA Fermi
Indirect Detection 75

76. Sterile neutrino DM
76

77. Sterile neutrino DM: line
Dark Matter Hot gas
expectation
νs → να + γ 77

78. Sterile neutrinos: limits
d ed
lu
E xc
Excluded by Ly-α
Bullet cluster
[Watson et al. 2006 (astro-ph/0605424)]
[Colafrancesco 2007] 78

79. [Yuksel et al. 2007]
[Colafrancesco 2007]
DUAL
NHXM Coma constraints from
20-80 keV emission
NEXT
nuStar
79

80. 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
80

81. Other DM options
81

82. Neutralino DM: particles
e- e+
p p-
…
82

83. Pamela and ATIC
Charge-dependent solar Rapid climb above 10 GeV
modulation important indicates the presence of a
below 5-10 GeV primary source of cosmic
ray positrons!
Pamela
ATIC
Astrophysical expectation
(secondary production) 83

84. HESS and Fermi
Fermi and HESS do not confirm ATIC: Astrophysics can explain PAMELA:
→ consistent with bkgd. expectations - Pulsars
- SN remnants
- Diffusion effects
Fermi Collaboration (2009)
[Zhang, Cheng (2001); Hooper et al. (2008)
Yuksel et al. (2008); Profumo (2008)
Fermi LAT Collaboration (2009)]
84

85. Outline
Multi-epoch
The Dark Matter Timeline
The present
Multi-Scale
DM search at various astronomical scales
• Galactic center
• Galactic structures
• Galaxy Clusters
The Future
The DM search challenge
85

86. 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)
What do we really know about dark matter?
Pause All solid evidence is gravitational
Also solid evidence against strong and EM interactions
The anomalies (DAMA, PAMELA, ATIC, …) are not easily explained
@ by canonical WIMPs → go beyond MSSM WIMP model
A reasonable 1st order guess:
Return Dark Matter has no SM gauge interactions, i.e., it is hidden
[Kobsarev, Okun, Pomeranchuk (1966); many others]
What one seemingly loses: [Feng et al. 2009]
Esc Connection to central problems of particle physics
Non-gravitational signals
86
The WIMP miracle

87. … some conclusions
• 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…
87

88. DM … or Modified Gravity !?!
Dark Matter
Could MOG explain also the dynamics
of the bullet cluster ?
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.
88

89. DM
G 89

90. THANKS
for your attention !
90