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We don ’t know it, because we don’t see it!. WdB, C. Sander, V. Zhukov, A. Gladyshev, D. Kazakov, EGRET excess of diffuse Galactic Gamma Rays as Tracer of DM , astro-ph/0508617, A&A, 4 44 (2005) 51. Dark Matter visible by Galactic Gamma Rays?. OUTLINE

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Dark matter visible by galactic gamma rays

We don’t know it,

because we don’t see it!

WdB, C. Sander, V. Zhukov, A. Gladyshev, D. Kazakov,

EGRET excess of diffuse Galactic Gamma Rays as

Tracer of DM, astro-ph/0508617, A&A, 444 (2005) 51

Dark Matter visible by Galactic Gamma Rays?

  • OUTLINE

  • Determination of the WIMP mass

  • Determination of the WIMP halo

  • Determination of the rotation curve

  • OBJECTIONS:

  • Antiproton fluxes

  • PREDICTIONS

  • forDM searches

  • for LHC

  • for neutrino telescopes


Dark matter visible by galactic gamma rays

http://www.sciam.com/

August 22, 2006

Colliding Clusters Shed Light on Dark Matter

  • 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 weakly interacting!


Thermal history of wimps

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  Expansions- rate,i.e. =<v>n(xfr)  H(xfr) !)

Thermal history of WIMPs

Thermal equilibrium abundance

Actual abundance

Comoving number density

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

Only assumption in this analysis:

WIMP = THERMAL RELIC!

x=m/T

Jungmann,Kamionkowski, Griest, PR 1995


Example of dm annihilation susy

f

f

f

~

f

A

Z

f

f

f

W

Z

0



Z

W

Example of DM annihilation (SUSY)

≈37

gammas

Quark-Fragmentation known!

Hence spectra of positrons,

gammas and antiprotons known!

Relative amount of ,p,e+ known

as well.

Dominant

 +   A  b bbar quark pair

Sum of diagrams should yield

<σv>=2.10-26 cm3/s to get

correct relic density


Dark matter visible by galactic gamma rays

Idea of indirect detection analysis

Idea:

Thermal relics disappeared by annihilation.

(From WMAP Annihilation cross section <σv>=2.10-27/Ωh2)

Annihilation into quarks with this x-section should yield

large amount of Gamma Rays (37 γ’s/Annihilation from LEP data)

Gamma spectrum from DMA significantly harder than dominant

background from inelastic pp collisions (Cosmic Rays on H-gas)

Background shape KNOWN from fixed target experiments,

DMA Gamma Ray shape KNOWN from LEP data

EGRET Data indeed shows such an expected excess with

SAME spectral SHAPE IN ALL SKY directions and

INTENSITY of excess allows to measure DM distribution

in GALAXY. Then one knows MASS distribution of DM and

visible matter and can calculate ROTATION CURVE (RC).

IF GAMMA RAYS indeed originate from DMA, then this

can be proven by calculating shape of RC from gamma rays!

WdB, C. Sander, V. Zhukov, A. Gladyshev, D. Kazakov,

EGRET excess of diffuse Galactic Gamma Rays as

Tracer of DM, astro-ph/0508617, A&A, 444 (2005) 51


Dark matter visible by galactic gamma rays

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


Dark matter visible by galactic gamma rays

π0

π0

WIMPS

IC

IC

Brems

Brems

The EGRET excess of diffuse galactic gamma rays

without and with DM annihilation

Fit only KNOWN shapes of BG + DMA, i.e. 1 or 2 parameter fit

NO GALACTIC models needed. Propagation of gammas straightforward

If normalization free, only relative point-to-point errors of ≤7% important,

not absolute normalization error of 15%. Statistical errors negligible.


Dark matter visible by galactic gamma rays

Quarks

from

WIMPS

Quarks

in protons

What about background shape?

No SM

No SM

Protons

Electrons

Background from nuclear interactions (mainly p+p-> π0 + X ->  + X

inverse Compton scattering (e-+  -> e- + )

Bremsstrahlung (e- + N -> e- +  + N)

Shape of background KNOWN if Cosmic Ray spectra of p and e- known


Energy loss times of electrons and nuclei

Energy loss times of electrons and nuclei

t-1

= 1/E dE/dt

univ

Protons diffuse for long times without loosing energy!

If centre would have harder spectrum, then hard to explain why excess

in outer galaxy has SAME shape (can be fitted with same WIMP mass!)


Dark matter visible by galactic gamma rays

Background + signal describe EGRET data!


Dark matter visible by galactic gamma rays

Analysis of EGRET Data in 6 sky directions

C: outer Galaxy

A: inner Galaxy

B: outer disc

Total 2 for all regions :28/36  Prob.= 0.8 Excess above background > 10σ.

E: intermediate lat.

F: galactic poles

D: low latitude

A: inner Galaxy (l=±300, |b|<50)

B: Galactic plane avoiding A

C: Outer Galaxy

D: low latitude (10-200)

E: intermediate lat. (20-600)

F: Galactic poles (60-900)


Dark matter visible by galactic gamma rays

SUPERSYMMETRIC DARK MATTER AND

THE EXTRAGALACTIC GAMMA RAY BACKGROUND

2/d.o.f=10.9/6  P=0.1

2/d.o.f=4.7/4  P=0.3

m =50 GeV

W.de Boer et al.,

Phys.Rev. Lett..95:209001,2005

D. Elssässer and K. Mannheim,

Phys.Rev.Lett.94:171302,2005


Dark matter visible by galactic gamma rays

bulge

disk

sun

Fits for 180 instead of 6 regions

180 regions:

80in 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


Dark matter visible by galactic gamma rays

Expected

Profile

Observed

Profile

z

xy

xy

Rotation Curve

2002,Newberg et al. Ibata et al,

Crane et al. Yanny et al.

x

y

1/r2 halo

totalDM

disk

xz

xz

bulge

Inner Ring

Outer Ring

1/r2 profile and rings

determined from inde-pendent directions

Normalize to solar velocity of 220 km/s

Dark Matter distribution

v2M/r=cons.

and

(M/r)/r2

1/r2

for const.

rotation

curve

Divergent for

r=0?

NFW1/r

Isotherm const.

Halo profile


Dark matter visible by galactic gamma rays

Rotation curve of Milky Way

Honma & Sofue (97)

Schneider &Terzian (83)

Brand & Blitz(93)


Dark matter visible by galactic gamma rays

Do other galaxies have bumps in rotation curves?

Sofue & Honma


Dark matter visible by galactic gamma rays

Tidal disruption of dwarf galaxy in

gravitational field of larger galaxy

From Eric Hayashi


Dark matter visible by galactic gamma rays

H2

Inner Ring coincides with ring of dust and H2 ->

gravitational potential well!

4 kpc coincides with ring of

neutral hydrogen molecules!

H+H->H2 in presence of dust->

grav. potential well at 4-5 kpc.

Enhancement of inner (outer) ring over 1/r2 profile 6 (8).

Mass in rings 0.3 (3)% of total DM


7 physics questions answered simultaneously if wimp thermal relic

Astrophysicists:

What is the origin of “GeV excess” of diffuse Galactic Gamma Rays?

Astronomers:

Why a change of slope in the galactic rotation curve at R0 ≈ 11 kpc?

Why ring of stars at 14 kpc?

Why ring of molecular hydrogen at 4 kpc?

Cosmologists: How is DM annihilating?A: into quark pairs

How is Cold Dark Matter distributed?

Particle physicists:

Is DM annihilating as expected in Supersymmetry?

7 Physics Questions answered SIMULTANEOUSLY if WIMP = thermal relic

A: DM annihilation

A: DM substructure

A: standard profile +

substructure

A: Cross sections perfectly consistent with mSUGRA

for light gauginos, heavy squarks/sleptons


Dark matter visible by galactic gamma rays

Objections against DMA interpretation

1) Does antiproton rate exclude interpretation of EGRET data? (L.B.)

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):

  • Flux of antiprotons/gamma in DarkSUSY: O(1) from DMA.

  • However, O(10-3-10-2) from LEP data

  • Reason: DS has diffusion box with isotropic diffusion ->

  • DMA fills up box with high density of antiprotons

  • 2) More realistic models have anisotropic diffusion.

  • E.g. spiral galaxies have magnetic fields perpendicular to

  • disk-> antiprotons may spiral quickly out of Galaxy.


Dark matter visible by galactic gamma rays

Magnetic fields observed in spiral galaxies

fieldline

disk

A few uG perpendicular to disc:

Strong convection to disc?

A few µG along spiral arms:

Can lead to slow radial diffusion

Isotropic diffusion assumes randomly oriented magnetic turbulences.

Preferred magnetic field directions -> anisotropic diffusion


Dark matter visible by galactic gamma rays

Preliminary results from GALPROP

with isotropic and anisotropic propagation

Antiprotons

B/C ratio

Summary: with anisotropic propagation you can send charged particles

whereever you want and still be consistent with B/C and 10Be/9Be


Dark matter visible by galactic gamma rays

EGRET EXCESS

Statistical

errors only

Sofue &Honma

R0=8.3

kpc

v

Inner

rotation

curve

R0=7.0

Outer RC

Black hole at centre: R0=8.00.4 kpc

R/R0

Objections against DMA interpretation

2) 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.

3) Ringlike structures have enhanced density of hydrogen, so you expect

excess of gamma radiation there. Why you need DMA?

Answer: since we fit only the shapes of signal and BG, a higher gas

density is automatically taken into account and DMA is needed

to fit the spectral shape of the data.

4) Is EGRET data reliable enough to make such strong statements?

Answer: EGRET spectrometer was calibrated in photon beam at

SLAC. Calibration carefully monitored in space. Impossible

to get calibration wrong in such a way that it fakes DMA.

Halo profile only sensitive to relative EGRET uncertainties

between different sky directions! MOST ERRORS DROP OUT!


Dark matter visible by galactic gamma rays

EGRET?

Cross sections for Direct DM detection in mSUGRA

mSUGRA: common masses m0 and m1/2 for spin 0 and spin ½ particles


Annihilation cross sections in m 0 m 1 2 plane 0 a 0 0

t t

bb

Annihilation cross sectionsin m0-m1/2 plane (μ > 0, A0=0)

tanβ=50-55

Annihilation cross sections can be calculated,if masses are known (couplings as in SM).

Assume not only gauge coupling

Unification at GUT scale, but

also mass unification, i.e. all

Spin 0 (spin 1/2) particles have masses m0 (m1/2).

For WMAP x-section of <v>2.10-26 cm3/s one needs

For small LSP mass (m1/2 ≈ 175 GeV) large values of (m0 ≈ 1-2 Tev) (and large tan β ≈ 50)

10-24

EGRET

WMAP



WW

mSUGRA: common masses m0 and m1/2 for spin 0 and spin ½ particles


Dark matter visible by galactic gamma rays

SUSY Mass spectra in mSUGRA

compatible with WMAP AND EGRET

Charginos, neutralinos

and gluinos light

LSP largely Bino  DM may be supersymmetric partner of CMB


Dark matter visible by galactic gamma rays

Gauge unification perfect with SUSY spectrum from EGRET

SM

SUSY

Update from Amaldi, dB,

Fürstenau, PLB 260 1991

NO FREE

PARAMETER

With SUSY spectrum from EGRET + WMAP data and start values of couplings from final LEP data perfect gauge coupling unification!

Also b->s and g-2 agree within 2σ with SUSY spectrum from EGRET


Dark matter visible by galactic gamma rays

EGRET and neutrino telescopes

higgsinolike

binolike

Orloff et al., hep-ph/0301215


Dark matter visible by galactic gamma rays

Summary

EGRET excess shows 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 models or unknown experimental problems may change boost factor 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 FROM GAMMA RAYS.

Conventional models CANNOT explain above points SIMULTANEOUSLY,

especially spectrum of gamma rays in all directions, 1/r2 profile, shape of

rotation curve, ring of stars at 14 kpc and ring of H2 at 4 kpc, ….


Dark matter visible by galactic gamma rays

Summary of summary

Indirect detection:

intriguing hint for signal from DMA for 60 GeV WIMP

Direct detection: expected to observe signal in near future

IF we are not in VOID of clumpy DM halo

LHC accelerator (2008-2018): cannot produce WIMPs directly

(too small cross section), BUT IF WIMPs

are Lightest Supersymmetric Particle (LSP) THEN

WIMPs observable in DECAY of SUSY particles

IF EVERY METHOD measures SAME WIMP mass, then PERFECT.


Dark matter visible by galactic gamma rays

Clustering of DM -> boosts annihilation rate

Annihilation  SQUARE of DM density

Clustersize: ≈ solar system?

Mmin 10-8 -100 Mסּ?

Steeply falling mass spectrum.

Boost factor  <2>/<>2  2-20000

(Berezinski, Dokuchaev,..)

From fit: B≈100 for WIMP of 60 GeV

Clumps with Mmin -> dominant

contribution -> MANY clumps in given direction -> same boostfactor in all directions


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