Karl Mannheim – ITPA Würzburg

Gamma rays from the Virgo and Gamma rays from the Virgo and Coma clusters of galaxiesComa clusters of galaxies

Berlin CTA-Meeting, May 4-5, 2006Berlin CTA-Meeting, May 4-5, 2006

Clusters of Galaxies

• Storage of (UHE) cosmic rays– Supernova-driven winds– Radiojets from Active Galactic Nuclei

• Acceleration of (UHE) cosmic rays– Cluster merger shocks– Accretion shocks– Dynamical relaxation shocks

• Dark matter annihilation – Largest mass concentrations– Small-scale clumps dominance: Sorting in

dM/R2

» Galactic Center» Nearest halo clump (unidentified EGRET?)» Nearest rich clusters (Virgo, Coma, Perseus)» Nearest dwarf galaxies (Sagittarius, Draco)

Galactic Vicinity (200 kpc)

Local Group (2 Mpc)

Local Universe (60 Mpc)

Local Universe (300 Mpc)

Virgo cluster

Coma cluster

Cosmic rays in nearby clusters of galaxies

Pfrommer et al.: Cosmic ray propagation model fitted to radio and X-ray observations, employing hydrodynamical code for of intracluster medium (-ray fluxes > 50 GeV)

Cosmic rays in Coma

Berrington & Dermer:

Cluster merger shock

Völk et al.: Cosmic ray propagation

Reimer et al. Cosmic ray propagation

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

M87 SED

(ICRC)

Structure Formation• ART Code (A. Klypin et al.)

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

• (sub)structure down to 3 £ 107 solar masses: clumps!

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

2DM ds

Summary

Clusters are cutting-edge targets for current IACTsRich potential for astrophysics, cosmology, and

particle physics

Origin of UHE cosmic rays Dark matter annihilation Role of nonthermal plasma in structure

formation

… northern location prefered for a dedicated„cluster mission“with future CTAs…