Hard X-Rays & Gamma-Rays Induced by Ultra High Energy Proton Acceleration in Cluster Accretion Shocks Susumu Inoue Felix Aharonian Naoshi Sugiyama (NAO Japan) accretion (inc. minor merger) p acceleration to E~ eV -> p+  CMB → p+ e + e - E~ eV -> e + e - +B(~  G) →syn. E  ~ keV e + e - +  CMB →IC E  ~TeV (MPIK Heidelberg) paper in prep.

shock formation in clusters hierarchical, dark matter-driven structure formation → merger & accretion shocks → gas heating + nonthermal particle acceleration → nonthermal radiation accretion (minor merger) e.g. Ryu et al. 03 strong (high M ) shock

nonthermal high energy emission from clusters Miniati ‘03 thermal>100 MeV>100 keV primary electron IC LE proton p+p->  0 UHE proton-induced pair syn.+IC c.f. Aharonian 02 Rordorf et al. 04 traces shock traces gas e.g. Waxman & Loeb 00 Gabici & Blasi 03 e.g. Dar & Shaviv 95 Völk et al. 96 Berezinsky et al. 97

maximum proton energy in accretion shocks accel. vs CMB/adiabatic losses photopion adiab. accel. B s =0.1  G photopair c.f. G.Farrar’s talk e.g. Kang, Ryu & Jones 96 Kang, Rachen & Biermann 97 accel. B s =1  G R s ~3.2 Mpc V s ~2200 km/s e.g. Coma-like cluster M=2x10 15 M  (T=8.2 keV) WMAP cosmo. parameters B s,eq ~ 6  G E max ~ eV t acc,Bohm =(20/3) r g c/V s 2 shock radius, velocity, etc. Bohm limit accel. SNR observations e.g. Bamba et al. 04

proton injection luminosity in accretion shocks accretion rate & luminosity M(M,z)=f gas f acc V s 3 /G L acc (M,z)=f gas f acc GMM/R s ~2.7*10 46 (f gas /0.16) (f acc /0.1) erg/s proton luminosity & spectrum L p (M,z)=f p L acc (M,z) f p =0.1 F p (E,M,z) ∝ E -2 exp(-E/E max ) f acc =0.1 normalization from simulation Keshet et al. ‘04 secondary production and emission processes p+  CMB → p+ e + e - E p ~10 18 eV E +- ~  +- E p ~10 15 eV, L +- ~t +- /t inj f(E> eV) L p → e + e - +B(~  G) → syn. E  ~keV-MeV e + e - +  CMB → IC E  ~TeV-PeV Aharonian 02 code solve pair kinetic eq...

emitted luminosity Coma-like cluster - large radiative efficiency from protons - hard (  ~-1.5) spectrum

emitted flux > TeV absorption by IRB, CMB Coma-like cluster at D=100 Mpc

emitted flux extended source sensitivity x (~3 deg/ang. res.) Coma-like cluster at D=100 Mpc caution: point source sensitivities

model vs Coma data perhaps not impossible? but need optimism radio something else

implications UHE p-induced emission in cluster accretion shocks probe of UHE proton acceleration probe of accretion shock probe of magnetic field at cluster outskirts probe of IR background

summary acceleration to E~ eV plausible efficient secondary pair production and emission -> sync. (hard X-MeV) detectable by ASTRO-E2/HXD, imagiable by NeXT -> IC (TeV) detectable by HESS and other current IACTs UHE p-induced emission in cluster accretion shocks contribution to extragalactic gamma background nonlinear effects in proton acceleration … more efficient than primary IC, p-p  0 next steps

Grazie mille! Merci beaucoup! Monte Bianco from Courmayeur