Transcript Evidence for WIMP Dark Matter Wim de Boer, Marc Herold, Christian Sander, Valery Zhukov Univ.

Evidence for WIMP Dark Matter
Wim de Boer, Marc Herold, Christian Sander, Valery Zhukov
Univ. Karlsruhe
Alex Gladyshev, Dmitri Kazakov
Dubna
Outline
•
(see astro-ph/0408272, hep-ph/0408166)
EGRET Data on diffuse Gamma Rays
shows excess in all sky directions with
the SAME spectrum
• Halo parameters from sky map
• WIMP mass from spectrum
• Data consistent with Supersymmetry
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Physics Problems
• Cosmologists:
What is CDM and Dark Energy made of?
• Particle physicists:
Where are the Supersymmetric Particles?
• Astrophysicists:
What is the origin of excess of diffuse Galactic
Gamma Rays?
• Astronomers:
Why a change of slope in the galactic rotation curve
at 1.1 R0?
Why ring of stars at 14 kpc so stable?
Why ring of molecular hydrogen at 4 kpc so stable?
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Proposed Solution
•DM made of WIMPS annihilating into quarks, which yield
hard gammas from 0 decays
•Annihilation cross section given by HUBBLE constant!
•Gamma excess correlated with ring of stars at 14-18 kpc
thought to originate from infall of a dwarf galaxy
and ring of DM at 4 kpc stabilizes ring of hydrogen
•From SPECTRUM of excess of gamma rays DM:
WIMP mass 50-100 GeV
•From INTENSITY: halo distribution and rotation curve
•WIMP has properties of supersymmetric lightest particle
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Executive Summary
Expected
Profile
xy
Observed
Profile
z
xy
Rotation Curve
x
xz
y
DM halo
2003, Ibata et al, Yanny et al.
disk
bulge
xz
Inner Ring
FR
FG
Outer Ring
Halo profile
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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WMAP determines WIMP annihilation x-section
Thermal equilibrium abundance
Comoving number density
Jungmann,Kamionkowski, Griest, PR 1995
Actual abundance
T>>M:
f+f->M+M; M+M->f+f
T<M:
M+M->f+f
T=M/25: M decouples, stable density
(wenn annihilation rate  expansion
rate, i.e. =<v>n  H !)
x=m/T
T=M/25
Sept, 2. 2004
Boltzmann equation:
H-Term takes care of decrease in density
by expansion. Right-hand side:
Annihilation and Production.
Neutralino annihilation is a strong
source of antiprotons, positrons and
gammas by annihilation into quarks.
Present number density (h2=0.1130.009)requires
<v>=2.10-26 cm3/s assuming no coannihilation
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Neutralino Annihilation Final States

f 
~
f 
f

f

A

W


f

f
Z

Z
0
W

Z
Dominant Diagram for WMAP
cross section:
 +   A  b bbar quark pair
Sept, 2. 2004
f
B-fragmentation well studied at LEP!
Yield and spectra of positrons,
gammas and antiprotons well known!
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Annihilation cross sections
in m0-m1/2 plane (μ > 0, A0=0)
tan=5
10-27
bb
tan=50
tt
10-24
bb
tt
EGRET

WW

WW
For WMAP x-section of <v>2.10-26 cm3/s one needs large tanβ
in bulk region (no coannihilation, no resonances)
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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EGRET excess interpreted as DM consistent with
WMAP, Supergravity and electroweak constraints
0
MSUGRA can fulfill
Stau coannihilation all constraints from WMAP,
LEP, b->s, g-2 and EGRET
simultaneously, if DM is
neutralino with mass
in range 50-100 GeV and
squarks and sleptons are
O(1 TeV)
WMAP
EGRET
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Strong, Moskalenko, Reimer, to be published
Excess of Diffuse Gamma Rays above 1 GeV
as measured by EGRET satellite (9 yrs of data)
B
A
C
Prel.
0
D
E
A: inner Galaxy (l=±300, |b|<50)
B: Galactic plane avoiding A
C: Outer Galaxy
Sept, 2. 2004
F
D: low latitude (10-200)
E: intermediate lat. (20-600)
F: Galactic poles (60-900)
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Local electron and proton spectra
determine shape of gamma background
No SM
No SM
Electrons
Protons
Solar modulation (SM) important below 10 GeV
Proton and electron spectra above 10 GeV well measured 
Gamma spectrum well known, unless one assumes “local bubble”,
i.e. spectra in galaxy different from locally measured ones.
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Excess of Diffuse Gamma Rays has same spectrum in all
directions compatible with WIMP mass of 50-100 GeV
Important: if experiment measures gamma rays down to 0.1 GeV, then normalizations of
DM annihihilation and background can both be left free, so one is not sensitive to absolute background estimates, BUT ONLY TO THE SHAPE, which is much better known.
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Diffuse Gamma Rays for different sky regions
A
D
B
C
E
F
DMA  Boostfactor <2> If boost factor, i.e. clustering, similar
in all directions, then signal strength determines DM density 
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Why LIGHT traces DM in disc
Reasons for enhanced DM in plane of galaxy:
1) Adiabatic compression of halo by gravity from disc
(Blumenthal, Kalnajs, Wilkinson,…..)
(halo distribution may be modified by resonant interactions
between bar and halo, Athanassoula, Weinberg, ..)
2) Anisotropic infall along filaments of DM
(e.g. ring of stars at 14-18 kpc thought to originate
from infall of dwarf galaxy (Yanny et al., Ibata et al., …)
Parametrize with at least 2 rings:
Inner ring for 1) Outer ring for 2)
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Fit results of halo parameters
Gamma Ray Flux: (<v> from WMAP) 2 rings with maximum
intensity at 4 and 14 kpc
Enhancement over isothermal
profile 3 and 8, respectively
Sensitive to radius, because
Halo Parameters: (assuming boost fct Bl Sun OFF CENTER!
same in all directions, comes out B>20)
H
H2
4
R [kpc]
14 kpc coincides with ring
of stars at 14-18 kpc due
to infall of dwarf galaxy
(Yanny, Ibata, …..)
4 kpc coincides with ring of
neutral hydrogen molecules!
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Halo profiles
Isothermal cored profile
WITHOUT rings
WITH rings
NFW cuspy profile
WITHOUT rings
WITH rings
100
10
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Longitude fits for isothermal (cored) profile
WITHOUT rings
WITH 2 rings
WITHOUT rings
DISC
DISC
100<b<200
50<b<100
50<b<100
200<b<900
WITH 2 rings
100<b<200
200<b<900
Halo parameters from fit to 180 sky directions: 4 long. profiles for
latitudes <50, 50<b<100, 100<b<200, 200<b<900 (=4x45=180 directions)
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Latitude fits for isoth. Profile with |long|<300
0.1 < E < 0.5 GeV
Sept, 2. 2004
E > 0.5 GeV
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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EGRET data compatible with prolate isothermal
halo profile with b/a  0.9, c/a  0.8
define the slope
0 - local density 0.3-0.7 GeV/cm3
a -scale parameter (depends on 0)
Isothermal profile: ,β,,a =
2,2,0,4
NFW cusp
W. de Boer et al., astro-ph/0408272
Isothermal core
y
b
Preferred structure
(Bailin, Steinmetz,astro-ph/0408163 z
Sept, 2. 2004
a
x
c
Ellipsoid: x2/a2 +y2/b2 + z2/c2 = c
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Rotation curve of our galaxy
FR
DM
bulge
FG
halo
disk
Inner Ring
Outer Ring
Rotation curve shows there is a ring of CDM with a mass of a few 1010 M‫סּ‬
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Local surface density Σ
Height distribution and velocity dispersion  of local stars determine
local gravitational potential (just like decrease in atmospheric density
is determined by gravity of earth).
Decrease in rotation curve suggests little Dark Matter.
First measurements:
van Oort in 1932: assuming constant : repulsive gravity.
Later: (z )  E.g. Σ= ∫dz = 716 M‫סּ‬/pc-2 for zmax=1.1 kpc
by Kuijken+ Gilmore, 1991. They assumed constant DM density and very
little of it. So they were stretching visible matter by brown dwarfs etc.
2001: Olling +Merrifield: consensus value of Σ from visible matter: 3510
2002: Bienayme et al.: Σ = 85? Error strongly dependent on assumptions
of DM distributions.
2004: de Boer et al.: ΣDM=60 Σbaryonic=30 M‫סּ‬/pc-2 with steeply varying
DM density steep function of z (on slope of ring!)
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Positron fraction and antiprotons
from DM annihilation
Positrons
Antiprotons
Antiprotons
SAME Halo and WIMP parameters as for GAMMA RAYS
but fluxes strong function of propagation models!
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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SUSY Mass spectra in mSUGRA
LSP largely Bino  DM may be
supersymmetric partner of CMB
Sept, 2. 2004
Charginos, neutralinos
and gluinos light
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Supersymmetry at linear collider
pb x-section!
Karl Ecklund, Cornell
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Supersymmetry at proton collider
Typical cross-sections (pb)
Silke Duensing
m [GeV]
pb x-section with very little background!
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Summary
1. Significant Excess (>10) of EGRET diffuse gamma ray data has
SAME shape in all sky directions, as expected for DM.
2. Excess outside disk follows cored (isothermal) halo profile, NO
CUSP
3. Independent evidence that EGRET excess indeed originates from
a)
b)
c)
d)
e)
DM annihilation follows from:
Strong signal from region with ring of stars at 14-18 kpc,
thought to be tidally disrupted dwarf galaxy
Strong signal from region with ring of molecul. hydrogen at 4 kpc
Gamma ray data used to predict rotation curve!
Orientation of disc along MINOR axis of prolate halo (as pred.)
Large local surface density
4. Alternative “conventional” models cannot explain stability of
ring of stars at 14 kpc and H2 ring of molecular gas at 4 kpc,
nor change of slope of rotation curve, nor halo shape of excess,
nor high local surface density
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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Summary of summary
EGRET galactic gamma ray data provides intriguing hint that
- since WIMP has properties of a spin ½ photon -
This conclusion is INDEPENDENT of the absolute normalization,
only dependent on the SHAPE of diffuse gamma ray spectrum!
Sept, 2. 2004
Durham, ILC Workshop, W. de Boer, Univ. Karlsruhe
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