23.09.2006Karl Mannheim: Dark Matter Annihilation in Clumpy Halos / DESY Theory Workshop 20061 DarK Matter Annihilation In Clumpy Halos DarK Matter Annihilation

23.09.2006 Karl Mannheim: Dark Matter Annihilation in Clumpy Halos / DESY Theory Workshop 2006 1

DarK Matter AnnihilationIn Clumpy Halos

DarK Matter AnnihilationIn Clumpy Halos

Collaboration with:

Dominik Elsässer

Acknowledgements:

Matthias Steinmetz et al. (AIP Potsdam) ART code N-body simulations Joakim Edsjö (ANI Stockholm) DARKSUSY Stefan Hofmann (PI Toronto) Transfer function for WIMPs Tanja Kneiske (U Adelaide) EGB due to blazars Olaf Reimer (U Stanford) EGB from EGRET Aldo Morselli (INFN Roma) Multi-messenger


DMA Folklore

New Twist

Consistent Model

Follow-Up

Elsässer & Mannheim, PRL 94, 1302 (2005)Elsässer & Mannheim, Astropart. Phys. 22, 65 (2004)


DMA Folklore: I. cold dark matter

DMA Folklore: I. cold dark matter

Cosmological structure formation

CDM = 0.23 Dark matter in Abell cluster (from gravitational lensing data)

Ostriker (2004)Cl0024+1654 (credit: J.-P- Kneib/ESA)


DMA Folklore:II. Lee-Weinberg Criterion

DMA Folklore:II. Lee-Weinberg Criterion

Thermal history of Universe WIMPs (A~pb, m~0.1-1TeV) freeze out

at CDM density CDM~<Av>-1

Weakly interacting massive particles at ~200 GeV are generic cold dark

matter

Turner 1992


DMA Folklore:III. Neutralino as WIMP

DMA Folklore:III. Neutralino as WIMP

Lightest stable particle in R-parity conserving supersymmetry (neutralino): color singlet at

electroweak scale with m ~ 2-1/4GF-1/2 = 246 GeV

Long-believed

smoking gun!

but…

GLAST brochureGoebel 2004


DMA Folklore:IV. Secondary gamma rays from

High density regions

DMA Folklore:IV. Secondary gamma rays from

High density regions

Clumpy dark matter halo

Numerical limitation ~ 106 M

Stoehr et al. 2003

2

Attractor in nonlinear simulations: NFW profile (=1)

Galaxy cluster Abell 85: simulation vs. observation

Cu

sp

2

Durett et al. 2006


DMA Folklore:V. Galactic Center shows

Too hard spectrum

DMA Folklore:V. Galactic Center shows

Too hard spectrum

2

MAGIC/HESS observe SgrA* as steady source with hard power law above ~100 GeV J. Albert et al., ApJ Letters 638, L101 (2006)


DMA Folklore:VI. Resume

DMA Folklore:VI. Resume

• Smoking-gun line feature at 100 GeV – 1 TeV not seen from Galactic Center (neither from M87)- Loop-suppressed or Z flux actually expected- Continuum flux from bb or WW peaks at 5 - 50 GeV- Relevant energy range currently inaccessible - Will open up with GLAST, HESS-II, and MAGIC-II

• Contribution to extragalactic background as inferred from EGRET data up to ~100 GeV- Expected to be small (Ullio et al. 2002; Ando 2005)- Extragalactic background: power law (Sreekumar et al. 98)- Galactic halo component of unknown origin with possible DMA

connection (Dixon et al. 98, de Boer et al. 2003)


New Twist:I. Extragalactic gamma ray

Background from EGRET

New Twist:I. Extragalactic gamma ray

Background from EGRET

• Improved foreground model (GALPROP) removes enigmatic Galactic halo component and leads to new EGB spectrum (Strong, Moskalenko, and Reimer 2004)• EGB shows excess above 1 GeV (from power law dN/dE~E-2.33)

Blazars

IACT sensitivity: ~1000 high-

peaked blazars

expected

~50

13 known VHE blazars

as of 2006 (E

CRC 2006)

EGRET >100 MeV


Example of new type of high-peaked blazars which contribute to the EGB

Example of new type of high-peaked blazars which contribute to the EGB

New HBL at high redshift z=0.182 discovered at 100 GeV (Albert et al., 2006, ApJ Lett. 642, L119)


Extragalactic Particle Accelerators – High Peaked BL Lacertae ObjectsExtragalactic Particle Accelerators – High Peaked BL Lacertae Objectspublished detections

•Discovery fraction of X-ray bright high-peaked blazars

(MAGIC 20h / source) ~ 30%

•200 high-peaked blazars extrapolated from X-ray catalogues / 3

~ 70 consistent with =2.33 extrapolation of sub-GeV EGB

•Positions of >10 GeV photons poorly correlated with positions

of known blazars (Thompson & Gehrels 2002)

•Thus: strong cosmological source of >GeV photons needed


Extragalactic gamma ray background contribution from HBLs based on the X-ray luminosity function of Beckmann (2003)

EGRET-type blazars

HBLs

Kneiske & Mannheim, ApJ (2006) submitted

Excess in EGB still remains!

Kneiske & Mannheim (2006)


New Twist:II. Halo Substructure

New Twist:II. Halo Substructure

• Power spectra of SUSY-CDM (Green, Hofmann, & Schwarz 2004)

• Small scale DM clumps down to 10-6 Mat a scale of 0.02 pc

• Collisional damping and free streaming smear out inhomogeneities at still smaller scales

• Full range of structures 10-6 M– 1015 M not resolvable with

current computing resources (Diemand, Moore, & Stadel 2005)

Large boost factor for DMA emission (~2ds)


New Twist:III. Cusp removal

New Twist:III. Cusp removal

Cusps can be destroyed by star formation feedback in high-z dwarfs (building blocks of galaxies)

Merger evolution of galaxies preserves core structure (Kravtsov & Gnedin 2002)

Small scale clumps may also be destroyed by tidal interactions with the gaseous disks (Silk et al.)

DMA signal of galaxy cores much weaker than signal from cluster cores

Dwarfs

Giants, Clusters

Mashenko et al., Nature 442, 539 (2006)


New Twist:IV. Other issues relevant for DMA

New Twist:IV. Other issues relevant for DMA

•Co-annihilation relaxes relation between A and DM (Baltz et al. 2006)•Anisotropy due to local clumps in DM halo (Elsässer & Mannheim 2004, Ando & Komatsu 2006) possible „smoking gun“•Problems with direct detection outside of clump•Detection of clumps from galactic halo with GLAST challenging (Pieri, Branchini, & Hofmann 2006)•Spikes around IMBHs (Bertone et al. 2005)•Positron excess measured by HEAT may be a hint for high-mass DMA (Edsjo 2002) •Synchrotron photon excess measured by WMAP („haze“) can be consistently explained by DMA (Finkbeiner 2004)

Baltz, Edsjö, Freese & Gondolo, Phys. Rev. D Baltz, Edsjö, Freese & Gondolo, Phys. Rev. D 6565, 063511 (2002), 063511 (2002)Coutou (2002)Coutou (2002)Tarle (2002)Tarle (2002)Kane, Wang, Wells (2001, 2002)Kane, Wang, Wells (2001, 2002)


Consistent Model:I. DMA Model for EGB above 1 GeV

Consistent Model:I. DMA Model for EGB above 1 GeV

Elsässer & Mannheim, PRL (2005)


Consistent Model:II. Galactic Center

Consistent Model:II. Galactic Center

Consistent with EGRET/HESS/MAGIC non-detection due to energy gap!Cf. Ando (PRL 2005): (i) fluxes for 100 GeV and 1 TeV WIMPs avoiding the energy gap (ii) no clumping

Other consistency checks:

Direct detection

Radio background

Diffuse gal. gamma rays

Antiprotons/Positrons

WMAP foreground

Muon magnetic moment

Relic density

=10-3sr

Severe problems for DMA identification:(i) cusp depletion(ii) clump disruption(iii) stellar-origin source confusion

Radial profileof signal strength

X – Ray image (Chandra)

Follow up:I. Galactic Center ( HESS-II, GLAST)

Follow up:I. Galactic Center ( HESS-II, GLAST)


Follow-up:II. Center of Virgo Cluster

(MAGIC-II, GLAST)

Follow-up:II. Center of Virgo Cluster

(MAGIC-II, GLAST)


M87 – Center of Virgo ClusterMAGIC Key Project

M 87 / Virgo Cluster

C=40

C=335

Targeted observations seem promising with new – generation experiments

DarkSusy scan

Control astrophysical backgrounds:-AGN in M87-CRp – interactions-MAGIC observations have started in May 2005

Gamma rays from the Dark Matter halo of M87

• ART Code (A. Klypin et al.)

• 3 1014 solar masses; 9 million particles („Virgo Cluster“)

• (sub)structure down to 3 107 solar masses

D. Elsaesser, S. Gottloeber, A. Khalathyan and M. Steinmetz

Gamma ray production ratedepends onthe line of sight integral

2DM ds

Clumping should lead to a signal detectableby MAGIC

M87 Spectral Energy Distribution

(ICRC)

2006


Gold-plated DMA signature in M87 at ~50 GeV: (i) Steady, soft spectrum (ii) clumpy morphology in FOV

Gold-plated DMA signature in M87 at ~50 GeV: (i) Steady, soft spectrum (ii) clumpy morphology in FOV

2nd telescope MAGIC-II in construction: improved clone of MAGIC

Stereo: improvement in terms of flux sensitivity, energy reconstruction and angular resolution

stereo


SummarySummary

Clumpy structure of DM halos (12 orders of magnitude below current numerical simulations) boosts DMA rate

Neutralino with a mass of ~520 GeV and <Av>~3 10-26cm3s-1 provides consistent model for EGB above GeV energies

Confirmation with next generation of gamma ray observatories feasible (GLAST, HESS-II, MAGIC-II)

Investigate LHC signatures for neutralinos which can successfully match the constraints of the model (astrophysical scenario largely insensitive to detailed SUSY parameters)

Documents

23.09.2006Karl Mannheim: Dark Matter Annihilation in Clumpy Halos / DESY Theory Workshop 20061 DarK Matter Annihilation In Clumpy Halos DarK Matter Annihilation