Transcript Folie 1

Dark Matter shining by Galactic gamma rays
and its possible implications for the LHC
From EGRET excess of diffuse
Galactic gamma rays
• Determination of WIMP mass
• Determination of WIMP halo
(= standard halo + DM ring)
Confirmation:
• Rotation curve
• Canis Major/Monoceros stream
• Gas flaring
PREDICTIONS
• for LHC (if SUSY)
• for direct searches
• for solar neutrinos
Wim de Boer, Karlsruhe
Ingredients
to this analysis
Rotation curve
Astronomers Tidal streams
Gas flaring
Astrophysics Cosmics
Gamma rays
23%DM, thermal
history of WIMPs
Cosmology Annihilation cross section
Tidal disruption of dwarfs
Gamma ray spectra
Particle Physics for BG + DMA
HEP2008, Chile, Jan. 8, 2008
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What is known about Dark Matter?
From CMB + SN1a + surveys
•
95% of the energy of the Universe is
non-baryonic
23% in the form of Cold Dark Matter
• Dark Matter enhanced in Galaxies and Clusters
of Galaxies but DM widely distributed in halo->
DM must consist of weakly interacting and
massive particles -> WIMP’s
•
If it is not dark
It does not matter
Annihilation with <σv>=2.10-26 cm3/s,
if thermal relic
DM halo profile of galaxy
cluster from weak lensing
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Colliding Clusters Shed Light on Dark Matter
http://www.sciam.com/
August 22, 2006
Observations with bullet cluster:
•Chandra X-ray telescope shows distribution of hot gas
•Hubble Space Telescope and others show distribution of Dark Matter
from gravitational lensing
•Distributions are clearly different after collision->
•dark matter is
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weakly interacting!
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Do we have Dark Matter in our Galaxy?
Rotationcurve
Solarsystem
1/r
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rotation curve
Milky Way
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Simple 3-Komponent Galaxy: p+e+Wimps
Interactions:
p+e <->H
p+p -> X
p+W -> p+W
W+W -> X
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electromagnetic x-section
strong x-section: 10-25 cm2
x-section:<10-43 cm2 (direct DM searches)
x-section: 10-33 cm2 (Hubble expansion)
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Expansion rate of universe determines
WIMP annihilation cross section
Thermal equilibrium abundance
Comoving number density
Actual abundance
T>>M:
f+f->M+M; M+M->f+f
T<M:
M+M->f+f
T=M/22: M decoupled, stable density
(wenn Annihilationrate  Expansionsrate, i.e. =<v>n(xfr)  H(xfr) !)
WMAP -> h2=0.1130.009 ->
<v>=2.10-26 cm3/s
DM increases in Galaxies:
1 WIMP/coffee cup 105 <ρ>.
DMA (ρ2) restarts again..
Annihilation into lighter particles, like
quarks and leptons -> 0’s -> Gammas!
T=M/22
x=m/T
Gary Steigmann/ Jungmann et al.
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Only assumption in this analysis:
WIMP = THERMAL RELIC!
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Example of DM annihilation (SUSY)

f 
~
f 
f

f


W


A
f

f
Z

f
≈37
gammas
Z
0
W

Z
Dominant
 +   A  b bbar quark pair
Sum of diagrams should yield
<σv>=2.10-26 cm3/s to get
correct relic density
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Quark fragmentation known!
Hence spectra of positrons,
gammas and antiprotons known!
Relative amount of ,p,e+ known
as well.
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Conclusion sofar
IF DM particles are thermal relics from early universe
they can annihilate with cross section as large as
<v>=2.10-26 cm3/s
which implies an enormous rate of gamma rays
from π0 decays (produced in quark fragmentation)
(Galaxy=1040 higher rate than any accelerator)
Expect significant fraction of energetic
Galactic gamma rays to come from DMA in this case.
Remaining ones from pCR+pGAS-> π0+X , π0->2γ
(+some IC+brems)
This means: Galactic gamma rays have 2 components
with a shape KNOWN from the 2 BEST studied reactions
in accelerators: background known from fixed target exp.
DMA known from e+e- annihilation (LEP)
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Basic principle for indirect dark matter searches
From rotation curve:
R1
Sun
R
bulge
disc
disc
Sun
Forces: mv2/r=GmM/r2
or M/r=const.for v=cons.
and
(M/r)/r2
1/r2
for flat rotation curve
Expect highest DM density
IN CENTRE OF GALAXY
Divergent for r=0?
NFW profile1/r
Isotherm profile const.
IF FLUX AND SHAPE MEASURED IN
ONE DIRECTION, THEN FLUX AND
SHAPE FIXED IN ALL (=180) SKY
DIRECTIONS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
THIS IS AN INCREDIBLE CONSTRAINT, LIKE SAYING I VERIFY
THE EXCESS AND WIMP MASS WITH 180 INDEPENDENT MEAS.
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EGRET on CGRO (Compton Gamma Ray Observ.)
Data publicly available from NASA archive
Instrumental parameters:
Energy range: 0.02-30 GeV
Energy resolution: ~20%
Effective area: 1500 cm2
Angular resol.: <0.50
Data taking: 1991-1994
Main results:
Catalogue of point sources
Excess in diffuse gamma rays
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Two results from EGRET paper
Called “Cosmic
enhancement
Factor”
Excess
Enhancement in ringlike
structure at 13-16 kpc
1
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10 Eγ GeV
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Background + signal describe EGRET data!
Background + DMA signal describe EGRET data!
50 GeV
PS
IM
0
Blue: background uncertainty
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IC
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IC
s.
em
Br
s.
em
Br
IC
W
IM
0
PS
W
70
Blue: WIMP mass uncertainty
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Analysis of EGRET Data in 6 sky directions
A: inner Galaxy
B: outer disc
C: outer Galaxy
Total 2 for all regions :28/36  Prob.= 0.8 Excess above background > 10σ.
E: intermediate lat.
D: low latitude
A: inner Galaxy (l=±300, |b|<50)
B: Galactic plane avoiding A
C: Outer Galaxy
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F: galactic poles
D: low latitude (10-200)
E: intermediate lat. (20-600)
F: Galactic poles (60-900)
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Fits for 180 instead of 6 regions
180 regions:
80 in longitude  45 bins
4 bins in latitude  00<|b|<50
50<|b|<100
100<|b|<200
200<|b|<900 
4x45=180 bins 
>1400 data points.
Reduced 2≈1 with 7% errors
BUT NEEDED IN ADDITION to
1/r2 profile, substructure
in the form of 2 doughnut-like
rings in the Galactic disc!
ONE RING COINCIDES WITH
ORBIT FROM CANIS MAJOR
DWARF GALAXY which looses
mass along orbit by tidal forces
OTHER RING coincides with H2 ring
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Dark Matter distribution
Expected
Profile
Observed
Profile
2M/r=cons.
vxy
and
(M/r)/r2
1/r2
for const.
xzrotation
curve
Divergent for
r=0?
NFW1/r
Isotherm const.
xy
xz
Halo profile
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Rotation Curve
2002,Newberg
et al. Ibata et
disk
al, Crane et al. Yanny et al.
bulge
Inner Ring
Outer Ring
1/r2 profile and rings determined
fromto inde-pendent
directions
Normalize
solar velocity of
220 km/s
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Halo density on scale of 300 kpc
Sideview
Topview
Cored isothermal profile with scale 4 kpc
Total mass: O(1012) solar masses
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Halo density on scale of 30 kpc
Sideview
Topview
Enhancement of inner (outer) ring
over 1/r2 profile 6 (8).
Mass in rings 0.3 (3)% of total DM
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How does DM substructure form
from tidal disruption of dwarf
galaxies?
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The Milky Way and its satellite galaxies
Canis Major
Tidal force  ΔFG  1/r3
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Tidal streams of dark matter from CM and Sgt
CM
Sun
Sgt
From David Law, Caltech
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Canis Major Dwarf orbits from N-body simulations
to fit visible ring of stars at 13 and 18 kpc
Movie from Nicolas Martin, Rodrigo Ibata
http://astro.u-strasbg.fr/images_ri/canm-e.html
Canis Major leaves at 13 kpc tidal stream of
gas(106 M☉ from 21 cm line), stars (108 M☉ ,visible),
Wim
dark
de Boer,
matter
Karlsruhe
(1010 HEP2008,
M☉, EGRET)
Chile, Jan. 8, 2008
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N-body simulation from Canis-Major dwarf galaxy
Observed stars
R=13 kpc,φ=-200,ε=0.8
Canis Major (b=-150)
prograde
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retrograde
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Gas flaring in the Milky Way
P M W Kalberla, L Dedes, J Kerp and U Haud,
http://arxiv.org/abs/0704.3925
no ring
with ring
Gas flaring needs EGRET ring with mass of 2.1010M☉!
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Inner Ring coincides with ring of dust and H2 ->
gravitational potential well!
H2
Enhancement of inner (outer) ring
over 1/r2 profile 6 (8).
Mass in rings 0.3 (3)% of total DM
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4 kpc coincides with ring of
neutral hydrogen molecules!
H+H->H2 in presence of dust->
grav. potential well at 4-5 kpc.
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Objections against DMA interpretation
Rotation curves in outer galaxy measured with different method
than inner rotation curve. Can you combine? Also it depends on R0.
Answer: first points of outer RC have same negative slope as inner RC
so no problem with method. Change of slope seen for every R0.
Sofue &Honma
v
Inner
rotation
curve
R0=8.3
kpc
R0=7.0
Outer RC
Black hole at centre: R0=8.00.4 kpc
R/R0
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Do antiproton data exclude interpretation of EGRET data?
Bergstrom et al. astro-ph/0603632, Abstract:
we investigate the viability of the model using the DarkSUSY
package to compute the gamma-ray and antiproton fluxes. We are
able to show that their (=WdB et al) model is excluded by a wide
margin from the measured flux of antiprotons.
Problem with DarkSUSY (DS):
1) Flux of antiprotons/gamma in DarkSUSY: O(1) from DMA.
However, O(10-2) from LEP data
Reason: DS has diffusion box with isotropic diffusion ->
DMA fills up box with high density of antiprotons
2) Priors of DARKSUSY.(and other propagation models as well):
a) static galactic magnetic fields are negligible
b) gas is smoothly distributed
c) propagation in halo and disk are the same
ALL priors likely wrong and can change predictions for DM searches
by ORDER OF MAGNITUDE (and still ok with all observations!)
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Another propagation model including static magnetic
fields and gas clouds and anisotropic diffusion
it is shown that Galactic
cosmic rays can be
effectively confined through
magnetic reflection by
molecular clouds,
Chandran, 1999
Galactic magnetic field (A0)
Fast propagation along regular field lines will reduce
antiproton flux from DMA, while grammage and lifetime
are determined by trapping in magnetic fields
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Escape time of cosmic rays and
grammage (distance x density)
B/C determines grammage
10Be/9Be
B/C=secondary/prim.determines
grammage (smaller than disc!)
In GALPROP: by large halo
In CHANDRAN: by reflecting
molecular clouds
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determines escape time
10Be
(t1/2 = 1.51 Myr) is cosmic
clock: lifetime of cosmics 107 yrs.
In GALPROP: by large halo
In CHANDRAN: by long trapping.
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Preliminary results from GALPROP
with isotropic and anisotropic propagation
CHANDRAN model
GALPROP model
Summary: with fast propagation perp. to disc (e.g. by convection,
fast diffusion or static magnetic fields) one reduces contribution
of charged particles from DMA by large factor and can be
consistent with B/C and 10Be/9Be
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What about
Supersymmetry?
Simplest model: mSUGRA with 5 parameters:
m0, m1/2, tan β, A0, sign µ
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EGRET excess interpreted as DM consistent with
WMAP, Supergravity and electroweak constraints
Stau coannihilation
Stau
LSP
Charginos, neutralinos
and gluinos light
Too large
boostfactor
for EGRET
data
WMAP
h<114
Bulk
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EGRET
LSP largely Bino  DM may be
supersymmetric partner of CMB
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mSUGRA cross sections
Main production channels:
MET+
Njets+
Nleptons
Contributions of different production channels
normalized to the total SUSY cross section
 tot [pb]
tan=50 A0=0
Total mSUGRA cross section(LO)
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KNLO =1.3-1.7
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mSUGRA topologies Different event topology in
different regions according to
masses and couplings..
mSUGRA averaged observables in m0-m1/2 plane
<Njets> ET>30 GeV
<MET>
Heff= MET+ET jets
+ETleptons
<N>muons PT>10 GeV/c
<PT> highest muon
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CMS FAMOS
<ET > highest jet
tan=50 A0=0
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Detector performance
Main trigger streams for SUSY
L1 Stream LL thresholds, GeV
1
14
2
3
29
e
2e
17
Jet+MET
88+45
Jets1(1,2,3,4)
177,86,70
Inclusive trigger efficiencies in
mSUGRA
plane HLT with respect to L1
L1 with respect to MC
.......
HLT Stream LL thresholds, GeV
1
19
2
7
29
e
2e
17
Jet+MET
180+123
Jets1(1,2,3,4)
657,247,113
.........
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Indirect DM detection from solar neutrinos
Celestial bodies collect DM
in their cores by their high density.
Annihilation can result in flux of
HIGH energy neutrinos from sun
(from b-decays or from Z-decays).
EGRET
SUN
Neutrinos can be detected by large
detectors,like Super-Kamiokande,
Amanda, Ice-Cube, Baksan
by the charged current interactions
with nuclei,which yields muons in the
detectors.
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Direct Detection of WIMPs
WIMPs elastically scatter off nuclei => nuclear recoils
Measure recoil energy spectrum in target
0
H,Z
EGRET?
0
If SUSY particle spectrum
known, elastic scattering
X-section can be calculated
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Clustering of DM
An artist picture of what we should see if our
eyes were sensitive to 3 GeV gamma rays and we
were flying with 220 km/s through the DM halo
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8 physics questions answered
SIMULTANEOUSLY if WIMP = thermal relic
• Astrophysicists:
What is the origin of “GeV excess” of diffuse
Galactic Gamma Rays? A: DM annihilation
• Astronomers:
Why a change of slope in the galactic rotation curve
at R0 ≈ 11 kpc?
A: DM substructure
Why ring of stars at 13 kpc?
Why ring of molecular hydrogen at 4 kpc?
Why S-shape in gas flaring?
• Cosmologists: How is DM annihilating?A: into quark pairs
How is Cold Dark Matter distributed?A: standard profile +
substructure
• Particle physicists:
Is DM annihilating as expected in Supersymmetry?
A: Cross sections perfectly consistent with mSUGRA
for light gauginos, heavy squarks/sleptons
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Summary
>>10σ EGRET excess shows intriguing hint that:
WIMP is thermal relic with expected annihilation into quark pairs
DM becomes visible by gamma rays from fragmentation
(30-40 gamma rays of few GeV pro annihilation from π0 decays)
Results rather model independent, since only KNOWN spectral shapes of
signal and background used, NO model dependent calculations of abs.fluxes.
Different shapes or unknown experimental problems may change the gamma
ray flux and/or WIMP mass, BUT NOT the distribution in the sky.
SPATIAL DISTRIBUTION of annihilation signal is signature for DMA
which clearly shows that EGRET excess is tracer of DM by fact that
one can construct rotation curve and tidal streams from gamma rays.
DM interpretation strongly supported independently by gas flaring
DM interpretation perfectly consistent with Supersymmetry
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