In memoriam- Hector Rubinstein
(1933 – 2009)
09-08-07
Jan Conrad, Stockholm Universitet
1
Summary (cosmic rays):
• General:
– CR probe DM on Galactic scales
– Cosmic ray propagation in the Galaxy is important for gamma-rays
and cosmic rays  needs imput from a variety of experiments.
– Instrumental and astrophysical backgrounds are challenging.
– Anti-deuterons provide a potential smoking gun signal
• Status:
– PAMELA let the genie out of the bottle
– Signatures detected which could be the first sign of DM.
– The experimental situation is confusing with different (apparently) not
consistent results (ATIC vs. Fermi !, PAMELA vs. Fermi ?).
• Outlook:
– Future experiments (AMS-02,PEBS) and additional data will be
crucial:
• For constraining backgrounds for e.g. gamma-rays and cosmic
rays.
• For distinguishing signal hypothesis.
09-08-07
Jan Conrad, Stockholm Universitet
2
• Lecture II
– Gamma-rays
• Signatures
• Astrophysics and backgrounds
• Experimental approach and experiments
• Source confusion
• Selected Results
– Neutrinos
• Signature
• backgrounds
• Experimental approach and experiments
• Selected results
• Impact of Astrophysics
– Interplay between different indirect experiments
– Indirect indirect detection (multi-wavelength)
Some additional slides contain more detailed information …
09-08-07
Jan Conrad, Stockholm Universitet
3
Dark Matter on Galactic and
cosmological scales
g - rays
g
c
p0
W-/Z/q
g
g
g
c
09-08-07
W+/Z /q
g
Jan Conrad, Stockholm Universitet
4
Signatures
Ullio et al. Phys.Rev.D66:123502,2002
cc  ...  p 0  gg
Birkedal et al.,
09-08-07
cc  gg
Bringmann et al. JHEP 0801:049,2008.
Jan Conrad, Stockholm Universitet
5
We are here
APP   ddl  (l )
2
09-08-07
Jan Conrad, Stockholm Universitet
6
Gamma-ray anisotropies
• DM structure is present.
• Main idea: annihilation quadratic in density, conventional
roughly linear
Couco et al., Phys.Rev.D77:123518,2008
EGB/cosmological
09-08-07
Jan Conrad, Stockholm Universitet
Siegal-Gaskins, JCAP 0810:040,2008.
Galactic
substructure
7
APP- halo density profile
Cored
profiles
from stellar
dynamics
09-08-07
 NFW (r ) 
 Bur ker t (r ) 
c
r 3 / 2 (a 3 / 2  r 3 / 2 )
c
r (a  r ) 2
c
(r  a )( a 2  r 2 )
log10 (APP)
Cuspy
profiles
from Nbody
simulations
 Moore (r ) 
Jan Conrad, Stockholm Universitet
Ullio et al. Phys.Rev.D66:123502,2002
8
Gamma-ray: detection principles (
< 300 GeV)
Anticoincidence
shield
Conversion foils
Particle tracking
detectors
+
e
09-08-07
–
e
Jan Conrad, Stockholm Universitet
Calorimeter
9
Fermi-LAT
• Main purpose:
g
– Photon detection with full
sky coverage in large
energy range (20 MeV-300
GeV), 5yr livetime (10 year
goal)
e e–
• Tracker
+
– Single sided SSD
(400 um, 225 um)
– W foil interleaved
– 18 xy planes
• ACD
– Segmented (89
plastic
scintillator tiles)
– 0.997 efficiency
09-08-07
Jan Conrad, Stockholm Universitet
• Calorimeter
– 1536 CsI(Tl)
crystals
– Hodoscopic
(12x8 layers)
10
Some photon candidates.
09-08-07
Jan Conrad, Stockholm Universitet
11
Gamma-rays: detection principle (> 100 GeV,
Air Cherenkov)
Gammaray
Particle
shower
~ 10 km
~ 1o
Key issue:
huge detection area
~ 105 m2
~ 120 m
09-08-07
Jan Conrad, Stockholm Universitet
12
HESS/VERITAS/MAGIC
VERITAS
4x12m IACTs
107 m2 mirror area each
MAGIC
2x17m IACTs
Observation in moonless
nights, ~1000 h / year
Each night 5-10 object are
tracked and 300 images
recorded per second
(10 TBytes / Jahr)
HESS
09-08-07
Jan Conrad, Stockholm Universitet
4x12m IACTs
(soon 5)
13
Gamma-rays: water cherenkov (> 1 TeV)
(MILAGRO/HAWC)
• Water tank
• ~ 700 PMTs
100 m
Nice game:
http://hawc.umd.edu/ghsep.php
09-08-07
Jan Conrad, Stockholm Universitet
14
Dark matter searches in gamma-rays
advantages
challenges
Galactic
Good
Source
center
Statistics
confusion/Diffuse
background
Subhalos
Low
Dwarf
background,
galaxies
Good source id
Milky Way
Large
Galactic diffuse
statistics
background
Extra-
Large
Astrophysics,
galactic
Statistics
galactic diffuse
halo
Low statistics
Baltz et al. JCAP 0807:013,2008
Search Technique
background
Spectral lines
09-08-07
No astrophysical
Low statistics
uncertainties,
Jan Conrad, Stockholm Universitet
good source id
15
Confusion with other sources?
5 yr GLAST, single
clump, 1 degree
Molecular cloud
rejected
rejected
200 GeV
30 GeV
WIMP
WIMP
allowed
rejected
09-08-07
Jan Conrad, Stockholm Universitet
Pulsar
Baltz et al., ApjL 659:L125
16
Source confusion
Source
Mono-
Extended
Non-variable
energetic
High-
No
latitude
counterparts
Quark
Spectrum
Subhalos
Molecular
clouds
Pulsars
Plerions
SNR
Blazars
09-08-07
Jan Conrad, Stockholm Universitet
17
Credit: J. Taylor
History lesson: GeV excess
Strong et al, ApJ 537, 736, 2000
Strong et al, ApJ 613, 962, 2004
”conventional” galprop
•
”optimized” galprop
Illustrates two things:
– There is still
considerable freedom in
astrophysical
backgrounds
– De Boer did not include
this in his calculations
(actually nobody ever
did)
09-08-07
Jan Conrad, Stockholm Universitet
W. De Boer et. al., 2003-2007
Dark matter
18
Galactic diffuse emission with
Fermi: GeV excess  gone.
Porter (Fermi-LAT), TevPA (2009)
09-08-07
Jan Conrad, Stockholm Universitet
19
Present results: generic WIMPs
Search Technique
Preliminary Fermi
benchmark : v  3 10-26 cm-3 s -1
limit
Galactic
10-25 @ 50 GeV
Center
ACT limits
10-26 > 200 GeV
(need Moore)
Dark matter satellites (blind
No detection in
Difficult to do
search)
11 month
Known dwarfs (Draco, Wilman
10-25 @ 30 GeV
…)
10-24
Milky Way
No result yet.
Difficult to do
10-25 @ 50 GeV
Difficult to do
10-24 >200 GeV
@ 1 TeV
halo
Extragalactic
-26 @ [30,100
Spectral
lines
(line
x-sec)
10
Jan
Conrad,
Stockholm
Universitet
09-08-07
GeV]
No results yet
20
Relevant gamma-ray telescopes
MILAGRO
VERITAS
AGIS
AMS
AGILE
MAGIC
HAWC
Fermi
future exp.
09-08-07
CTA
HESS
Jan Conrad, Stockholm Universitet
CANGAROO
21
Gamma-rays: sensitvitiy overview
Fermi:
Large
FOV
 (E ) ~ 10%
ACTs:
 (E ) ~ 15%
Water Che
 (E ) ~ 100%
AGIS
09-08-07
Jan Conrad, Stockholm Universitet
ACT/Fermi:
angular
resolutonn (0.10)
at high energies
(WC: ~0,5)
22
Summary: gamma-rays
• General:
– Gamma-rays provide a wealth of approaches to find DM
annihilation signal
– Instrumental and astrophysical backgrounds are challenging
– … but there are smoking guns existing …
• Status:
– Fermi has just completed 1 year  no evidence of DM signal, some
interesting constraints (in light of PAMELA, in light of EGRET
claims)
• Outlook:
– Much more to expect from Fermi in the next decade (in terms of
signal, in terms of constraining background)
– VERITAS results to be expected, MAGIC II ramping up.
– HESS II pushes the detection threshold down to ~20 GeV, ramping
up
– CTA/AGIS progressing  operational within the next 5 years!?
– HAWC in prototype phase
09-08-07
Jan Conrad, Stockholm Universitet
23
Dark Matter in the solar system
Neutrinos
W-/Z/q n
_
W+/Z /q n
p
nm
m
nmne
c
09-08-07
Jan Conrad, Stockholm Universitet
24
Neutrinos: detection from the Sun
(or Earth)
c
nm
09-08-07
Jan Conrad, Stockholm Universitet
m
25
Neutrinos: signature
J. Edsjö, PhD thesis, Uppsala University, 1997
09-08-07
Jan Conrad, Stockholm Universitet
26
Neutrino spectrum
09-08-07
Jan Conrad, Stockholm Universitet
27
Neutrinos: detection technique: Cherenkov
radiation
09-08-07
Jan Conrad, Stockholm Universitet
28
Neutrinos: backgrounds
O(109 ) / yr
O(103) / yr
O(10) / yr
09-08-07
Negligible
Jan Conrad, Stockholm Universitet
background from CR
induced neutrinos from Sun
29
ICECUBE
In the ice:
2009: 59 strings (running)
(includes 1 deep core)
Planned:
2011: 86 strings (5500 OM)
(includes 6 deep core)
15-year design lifetime
09-08-07
Jan Conrad, Stockholm Universitet
30
Track reconstruction: example from
Icecube
09-08-07
Jan Conrad, Stockholm Universitet
31
ANTARES (completed May 2008)
09-08-07
Jan Conrad, Stockholm Universitet
32
Neutrinos: limits from ICE3
• arXiv:0902.2460
arXiv:0902.2460
G. Wikström, PhD thesis,
Stockholm University
• Main ingredients for the expected rates are the velocity
distribution and the scattering cross-sections.
• WIMP scatter through axial and scalar couplings,
Neutrino telescopes are very sensitive to axial couplings
(spin-dependent), due to solar abundance
09-08-07
Jan Conrad, Stockholm Universitet
33
Example: constraints dependence on
astrophysical factor
Bruch et al., Phys.Lett.B674:250-256,2009
09-08-07
Jan Conrad, Stockholm Universitet
34
The world of neutrino telescopes
GVD
BAIKAL
ANTARES
KM3NET
NEMO
NESTOR
09-08-07
Jan Conrad, Stockholm Universitet
ICECUBE
35
Neutrinos: sensitivity comparison
09-08-07
Jan Conrad, Stockholm Universitet
36
Summary (neutrinos):
• General:
– Excess of neutrinos from the Sun provides a smoking gun
signal.
– Neutrino telescopes competitive for spin-dependent
dominated models.
• Status:
– ICECUBE-22 has presented first results. World-best limit on
SD x-section)
– ANTARES completed mid of 2008
• Outlook:
– ICECUBE-80/Deepcore ready by 2011
– Km3net in design study phase ~2016
– GVD
09-08-07
Jan Conrad, Stockholm Universitet
37
Inter-experiment cross-checks:
example 1: gamma vs. Anti-protons
Bergström et al., Phys. Rev.D:083515,2001
Has been used
to refute de Boer claims on
DM:
Bergström et al,
JCAP 0605:006, 2006
09-08-07
Jan Conrad, Stockholm Universitet
38
Inter-experiment cross-checks:
Example2: PAMELA vs. Fermi. Vs. Icecube
T. Jeltema (Fermi-LAT), TeVPA 2009
L. Bergström et al., 0905.0333
Fermi results
clusters
Fermi
PAMELA
09-08-07
Jan Conrad, Stockholm Universitet
ICE3 pred.
halo
39
Spolyar et. al, arXiv:0905.4764v1
”Indirect” indirect detection
09-08-07
Jan Conrad, Stockholm Universitet
40
What do I mean?
• There a number of other instruments
important for DM detection (mainly radio
and X-ray telescopes)
– CHANDRA,WMAP, VLA, ALMA, Parkes, Bonn …..
• Why?
– So far not considered: interaction/backreaction
of electrons and positrons on the surrounding
radiation gives rise to a broad-band spectrum
due to:
– Synchrotron radiation,
– Inverse compton (IC)
– Bremsstrahlung
Especially important for
”leptophilic” models
invoked to explain PAMELA
Jan Conrad, Stockholm Universitet
09-08-07
results
41
Example for indirect indirect detection
extragalactic background - IC
Zaharijas (Fermi-LAT),
TevPA (2009)
See further e.g.: Boriello et al., Astrophys. J.699:L59-L63, 2009 (Halo)
Regis et al. Phys. Rev.D78:043505,2008 (GC)
Colafrancesco et. al. astro-ph/0702568 (SZ effect, clusters)
Colafrancesco et al. Phys. Rev. D75:023513,2007 (Dwarfs)
etc,etc ……
09-08-07
Jan Conrad, Stockholm Universitet
42
All experiments mentioned (~30)
future exp.
TRACER
MILAGRO
VERITAS
AGIS
KM3NET
ANTARES
MAGIC
GVD
BAIKAL
AGILE
NEMO
NESTOR
AMS
PAMELA
PEBS
HAWC
Fermi
HESS
CTA
CANGAROO
VLA, HEAO-3, WMAP, Bonn, Parkes ,
COBE, FIRAS, Planck, Alma,Chandra
09-08-07
BESS-polar ICECUBE
Jan Conrad, Stockholm Universitet
PPB-Bets ATIC
GAPS
CREAM
CALET
43
Conclusions & Final remarks
• Indirect detection of Dark Matter is hard: signal is weak,
background (diffuse emission, astrophysical sources) is uncertain
( learning about these backgrounds is of utmost importance and
there is hope).
• However, many handles (interplay between different experiments
and ”indirect indirect detection”) ……
• … and couple of smoking gun signatures
– Line features and bumps (direct annihilation, FSR, IB)
– Antideuteron flux
– Excess neutrino emission from the Sun or the Earth..
09-08-07
Jan Conrad, Stockholm Universitet
44
Conclusions and final remarks II
• Revolutions are on the horizon! Fermi completed only 1
year, PAMELA results are only the beginning
• AMS-02 (manifested on the last shuttle flight)
• HESSII, VERITAS, MAGICII, ICECUBE (ramping up)
• PEBS, CALET, CTA/AGIS, HAWC (planning or
prototyping phase) operational under next 10 years.
• Contributions from VLA, ALMA,
CHANDRA,CREAM,TRACER …….
After 20 years of theory, finally theory meets reality.
The exploration of the dark sector has just begun !
09-08-07
Jan Conrad, Stockholm Universitet
45
Additional slides
09-08-07
Jan Conrad, Stockholm Universitet
46
Many fits of DM to signals –but no
discovery – why is that?
• 1. EGRET GC source (Mayer-Hasselwander,
1998)
• 2. EGRET Halo (Dixon et. Al, 1998)
• 3. HEAT excess (Couto, et. Al, 1999)
• 4. INTEGRAL (511 keV line, Knodelseder et. al,
2003).
• 5. EGRET extragalactic BG (Strong et. al 2004)
• 6. EGRET diffuse galactic emission (de Boer
2005)
• 6. ATIC
• 7. PAMELA excess (Adriani et. al, 2008)
Weak signal requires clean signature or well understood
Jan Conrad, Stockholm Universitet
09-08-07
backgrounds
47
Auxiliary measurements: B/C ratio
• Primary nuclei spectral index depend on injection spectrum
index and energy dependence of diffusion coefficient
• Primary/secondary ratio  injection index cancels, only
dependent on energy dependence of diffusion coefficient.
•
….also sensitive to propagation mode …..
δ:
0.3
0.45
0.6
0.7
09-08-07
Jan Conrad, Stockholm Universitet
Castellina et al., Astropart. Phys.24:146-159,2005
0.85
49
Why stereoscopic ?
09-08-07
Jan Conrad, Stockholm Universitet
50
Can it be that Fermi misses the ATIC
bump?
• Can it be energy resolution?
Unlikely
– HESS exercise
– PPB-Bets has 12 % resolution
• Can it be proton background
(Fermi being over-conservative)
?
Fazely et al., arXiv:0904.2371
09-08-07
Jan Conrad, Stockholm Universitet
51
More details on HESS II
MAGIC
identical
scale
HESS II
under construction
HESS I
09-08-07
Jan Conrad, Stockholm Universitet
52
More on dwarfs:
• dSphs are the most DM dominated systems known in the
Universe with very high M/L ratios.
• Many of them (at least 6) closer than 100 kpc to the GC (e.g.
Draco, Umi, Sagittarius and new SDSS dwarfs).
• SDSS [only ¼ of the sky covered] already double the
number of dSphs these last years
• Most of them are expected to be free from any other
astrophysical gamma source´, with low gas
• In comparison with the GC possibly the better option
09-08-07
Jan Conrad, Stockholm Universitet
53
Dwarf Galaxies - results
Veritas Wilman 1 (15 h)
E. Nuss (Fermi collab.), ICRC 2009
10-25
(MAGIC), ApJ.679:428-431,2008
Farnier (HESS collab.) IDM 2008
10-25
10-25
09-08-07
Jan Conrad, Stockholm Universitet
54
Resulst on the Galactic Center
J. Ripken (HESS, ICRC 2009)
10-25
C. Meurer, (Fermi, TeVPA 2009)
1o x 1o degree,
background is
not subtracted,
spatial info not
taken into
10-25
account
09-08-07
Jan Conrad, Stockholm Universitet
55
More details on cosmological WIMP
Halo
annihilation …..
Particle Physics
(annihilation xsection)
structures
(NFW etc.
subhaloes)
and halo mass
function
Cosmology
Particle Physics
(continuum plus
line yield)
Absorption
Ullio, Bergström, Edsjö, Lacey
Phys Rev. D. 66 123502 (2002)
09-08-07
Jan Conrad, Stockholm Universitet
56
Extragalactic diffuse emission?
09-08-07
Jan Conrad, Stockholm Universitet
57
Fermi measurement of EGB:
consistent with powerlaw
Ackermann (Fermi-LAT), TevPA (2009)
09-08-07
Jan Conrad, Stockholm Universitet
Remember relevance of charged particle background
58