Gamma-Rays and UHE Cosmic Rays from Clusters of Galaxies Susumu Inoue (Nat. Astron. Obs. Japan) and collaborators GeV 100 keV HESS Auger GLAST Suzaku ZeV TeV

outline 1. introduction 2. gamma-ray emission from clusters 3. UHE cosmic rays from clusters - UHE proton - photon pair syn.+IC - UHE cosmic ray nuclei (and photopairs) I, Aharonian & Sugiyama I, Sigl, Armengaud & Miniati - cascading (pair “halo”) I, Coppi & Aharonian “Multi-messenger-nisme”

current evidence for nonthermal emission: Coma1. introduction radio Giovannini et al. 93 hard X-ray Fusco-Femiano et al. 04 Rossetti & Molendi  detection no detection gamma-rayno clear evidence yet! GeV Reimer et al. 03 EUV Bowyer et al. 04 TeV Perkins et al. 06 Renaud et al. astro-ph/

large scale structure formation (SF) shocks formation of galaxies, groups, clusters... = hierarchical, dark matter-driven mergers and accretion → shock formation → gas heating + nonthermal particle acceleration → nonthermal radiation cosmological hydro simulations by Ryu et al. 03 shock velocitiesthermal emission clusters are forming this very moment!

cluster accretion shocks accretion (minor merger) (major) merger Ryu et al. 03 strong (high M ) shock -> high injection, hard spectra weak (low M ) shock -> low injection, soft spectra crucial for nonthermal high energy phenomena

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, Grasso & Dolag ‘04 traces shock traces gas e.g. Waxman & Loeb 00 Totani & Kitayama 00 e.g. Völk et al. 96 Berezinsky et al. 97 t IC <<t shock t loss, t conf >>t H

UHE proton-induced pair emission from cluster accretion shocks accel. vs CMB losses, lifetime photopion lifetime escape accel. B s =0.1  G photopair accel. B s =1  G e.g. Coma-like cluster M=2x10 15 M  (T=8.3 keV) WMAP cosmo. parameters Inoue, Aharonian & Sugiyama 2005 ApJ 628, L9 proton E max c.f. Kang, Rachen & Biermann 97 R s ~3.2 Mpc V s ~2200 km/s B s,eq ~ 6  G E max ~ eV photopair important t acc =(20/3)  r g c/V s 2 shock radius, velocity, etc. Bohm limit shock accel. time SNR observations  ~1 e.g. Völk et al. 05 escape time t esc ~R 2 /D(E=E max )~R/V~2 Gyr shock lifetime t sl ~R/V~2 Gyr < t adiab ~6 Gyr

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 ~2.7x10 46 (f gas /0.16) (f acc /0.1) (M/ 2x10 15 M  ) 5/3 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 normalized from simulation Keshet et al. 03 secondary production and emission processes p+  CMB → p+ e + e - E p ~10 18 eV E +- ~  +- E p ~10 15 eV → e + e - +B(~  G) → syn. E  ~keV-MeV e + e - +  CMB → IC E  ~TeV-PeV Aharonian 02 solve proton & pair kinetic eq...

emitted flux & detectability Coma-like cluster at D=100 Mpc sensitivities for 1 deg 2 extended source - large radiative efficiency from protons - hard (  ~-1.5) spectrum + rollover - sensitive to B c.f. primary IC, pp  0 (  ~-2) > TeV “absorption” by IRB+CMB Suzaku, NeXT HESS, MAGIC, CANG.3, etc. 5  100h

cascade emission: pair “halo” pre-“absorbed” flux cascade down to GeV-TeV cluster pair “halos” - isotropic (much stronger than beamed sources) - hard spectrum also for p-p  0 from core probe of IRB, TeV-PeV power Aharonian, Coppi & Völk 94 Coppi & Aharonian 97

3. UHECRs from cluster accretion shocks? Norman, Achterberg & Melrose ‘95 Kang, Ryu & Jones 96 Kang, Rachen & Biermann 97 GRB AGN jet clusters energetic requirements L cluster ~10 46 erg/s n cluster ~10 -6 Mpc -3 P cluster ~~10 40 erg s -1 Mpc eV u CR ~ erg cm -3  CR ~0.3(1) Gyr for p (Fe) P CR ~3x10 37 erg s -1 Mpc -3 massive clusters (~10 15 M  ) energetically plausible but proton E max insufficient oblique shocks do not help Ostrowski & Siemieniec-Ozieblo 00 “Hillas plot” adapted from Yoshida & Dai 98

UHECRs: energy losses during propagation p+  CMB → p+ e + e - E p >~5x10 17 eV p+  CMB → p+  E p >~7x10 19 eV L p, 20eV <~100 Mpc A+  CMB → A+ e + e - A+  FIRB → A-iN +iN Nagano & Watson 00 Fe p  E L loss L Fe, 20eV <~300 Mpc protons: photopair+photopion nuclei: photopair+photodisint. e.g. Stecker & Salamon 99 E>2x10 19 eV no data at all (too low statistics) E<2x10 19 eV light dominant but greater uncertainties than commonly believed? current data on composition HiRes stereo Xmax Watson astro-ph/

nuclei from cluster accretion shocks as UHECRs photodisint photopair B s =0.1  G B s =1  G heavy nuclei E max for B s ~1  G, E Fe, max >~10 20 eV Inoue, Sigl, Armengaud & Miniati in prep. UHE nuclei propagation calculations 56 Fe lifetime escape log E [eV] log t acc, t loss [yr] B s ~1  G Johnston-Hollitt & Ekers 05 - simulation-based structured IGB models (also no IGB case) - source density n s ~10 -6 Mpc -3 ∝ baryon density - source power L CR (M)~ 3x10 45 erg/s (f CR /0.1)(M/2x10 15 M  ) 5/3 - spectral index p=2, E max (Z) from t acc vs. t loss, t life - Galactic CR-like source composition (n Fe /n p ~10 -3 at fixed E/A) - CMB+FIRB losses, IGB deflections inc. all secondary nuclei Feretti & Neumann 06

UHE nuclei from clusters: results with IGB no IGB spectracomposition anisotropy spectra, anisotropy, composition consistent with current HiRes but not AGASA? higher B s ? predictions: - “GZK” cutoff >10 20 eV - heavy dominant >10 19 eV - large scale aniso. toward few nearby sources Auger, TA, EUSO eV eV eV f CR ~0.03 f CR ~0.005

source composition “Galactic CR-like” (solar metallicity) metallicity outside clusters (warm-hot IGM filaments) hard spectra at high E p<~1.5 Drury, Meyer & Ellison 99 nonlinear acceleration effects? Kang & Jones 05 rigidity selection (heavy enhancement) stronger effects for accretion shocks? Nicastro et al 05 ~0.1 solar (X-ray absorption) ~0.2 solar (simulations) Cen & Ostriker astro-ph/

UHE nuclei induced pairs and emission photodisint photopair B s =0.1  G B s =1  G nuclei photopair+photodisint. loss important additional hard X-ray and  -ray emission, broader spectra? 56 Fe 16 O lifetime escape direct proof of nuclei acceleration constrain source composition potentially E e+e-,A ~(m e /Am p ) Z E p E e-,ndec ~(m n-p /Am p )Z E p

summary expected high energy emission from clusters primary inverse Compton outskirts, MeV-GeV p-p  0 core, GeV-TeV p-p e +- core, MeV UHE p photopair emission outskirts, MeV+TeV cascade emission (pair halo) larger scales, GeV-TeV UHECR nuclei EeV-ZeV different components dominate at different energy, location potential probe of cluster evolution new type of high energy source potentially very rich information fertile new field of high energy astrophysics (Renaixança)! e.g. non-gravitational energy injection, I & Nagashima, in prep. but very little neutrinos…