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Gamma-Rays and UHE Cosmic Rays from Clusters of Galaxies

Gamma-Rays and UHE Cosmic Rays from Clusters of Galaxies. Susumu Inoue (Nat. Astron. Obs. Japan) and collaborators. GLAST. Suzaku. GeV. 100 keV. Auger. HESS. ZeV. TeV. outline. 1. introduction. 2. gamma-ray emission from clusters. - UHE proton - photon pair syn.+IC.

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Gamma-Rays and UHE Cosmic Rays from Clusters of Galaxies

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

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

  3. 1. introduction radio hard X-ray Giovannini et al. 93 current evidence for nonthermal emission: Coma Fusco-Femiano et al. 04 4.8s detection Rossetti & Molendi 04 EUV no detection Bowyer et al. 04 Renaud et al. astro-ph/0606114 gamma-ray no clear evidence yet! GeV Reimer et al. 03 TeV Perkins et al. 06

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

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

  6. primary electron IC traces shock e.g. Waxman & Loeb 00 Totani & Kitayama 00 nonthermal high energy emission from clusters tIC<<tshock • LE proton p+p->p0 traces gas e.g. Völk et al. 96 Berezinsky et al. 97 tloss, tconf>>tH Miniati ‘03 >100 keV thermal >100 MeV • UHE proton-induced pair syn.+IC c.f. Aharonian 02 Rordorf, Grasso & Dolag ‘04

  7. Inoue, Aharonian & Sugiyama 2005 ApJ 628, L9 UHE proton-induced pair emission from cluster accretion shocks e.g. Coma-like cluster M=2x1015 MQ(T=8.3 keV) WMAP cosmo. parameters proton Emax accel. vs CMB losses, lifetime photopair shock radius, velocity, etc. Rs~3.2 Mpc Vs~2200 km/s Bs,eq~ 6 mG lifetime escape Bohm limit shock accel. time accel. Bs=0.1 mG tacc=(20/3) h rgc/Vs2 SNR observations h~1e.g. Völk et al. 05 accel. Bs=1 mG photopion escape time tesc~R2/D(E=Emax)~R/V~2 Gyr shock lifetime tsl~R/V~2 Gyr < tadiab~6 Gyr Emax~1018-1019 eVphotopair important c.f. Kang, Rachen & Biermann 97

  8. secondary production and emission processes p+gCMB→ p+ e+e-Ep~1018eV E+-~k+-Ep~1015eV proton injection luminosity in accretion shocks →e+e-+B(~mG)→ syn. Eg~keV-MeV e+e-+gCMB→ IC Eg~TeV-PeV . accretion rate & luminosity M(M,z)=fgasfaccVs3/G Lacc(M,z)=fgasfaccGMM/Rs ~2.7x1046 (fgas/0.16) (facc/0.1) (M/ 2x1015 MQ)5/3 erg/s . facc=0.1 normalized from simulation Keshet et al. 03 proton luminosity & spectrum Lp(M,z)=fpLacc(M,z) fp=0.1 Fp(E,M,z) ∝ E-2 exp(-E/Emax) Aharonian 02 solve proton & pair kinetic eq.

  9. Coma-like cluster at D=100 Mpc > TeV “absorption” by IRB+CMB sensitivities for 1 deg2 extended source emitted flux & detectability 5s 100h Suzaku, NeXT • large radiative efficiency from protons- hard (G~-1.5) spectrum + rollover- sensitive to B HESS, MAGIC, CANG.3, etc. c.f. primary IC, pp p0 (G~-2)

  10. Aharonian, Coppi & Völk 94 Coppi & Aharonian 97 cascade emission: pair “halo” pre-“absorbed” flux cascade down to GeV-TeV also for p-p p0 from core cluster pair “halos”- isotropic(much stronger than beamed sources)- hard spectrum probe of IRB, TeV-PeV power

  11. adapted from Yoshida & Dai 98 “Hillas plot” 3. UHECRs from cluster accretion shocks? Norman, Achterberg & Melrose ‘95 Kang, Ryu & Jones 96 Kang, Rachen & Biermann 97 energetic requirements GRB UHECR@1020 eV uCR ~10-20 erg cm-3 tCR ~0.3(1) Gyr for p (Fe) PCR ~3x1037 erg s-1Mpc-3 AGN jet massive clusters (~1015 MQ) Lcluster~1046 erg/s ncluster~10-6 Mpc-3 Pcluster~~1040 erg s-1Mpc-3 clusters energetically plausible but proton Emax insufficient oblique shocks do not help Ostrowski & Siemieniec-Ozieblo 00

  12. UHECRs: energy losses during propagation protons: photopair+photopion p+gCMB→ p+ e+e- Ep>~5x1017eVp+gCMB→ p+ p Ep>~7x1019eV Fe Lloss p Lp, 20eV <~100 Mpc nuclei: photopair+photodisint. g A+gCMB→ A+ e+e-A+gFIRB→ A-iN +iN Nagano & Watson 00 e.g. Stecker & Salamon 99 LFe, 20eV <~300 Mpc E current data on composition HiRes stereo Xmax E>2x1019 eV no data at all (too low statistics) E<2x1019 eV light dominant but greater uncertainties than commonly believed? Watson astro-ph/0408110

  13. Inoue, Sigl, Armengaud & Miniati in prep. nuclei from cluster accretion shocks as UHECRs photopair 56Fe heavy nuclei Emax for Bs~1 mG, EFe, max>~1020 eV Bs=0.1 mG lifetime escape log tacc, tloss [yr] Bs~1 mG Johnston-Hollitt & Ekers 05 Feretti & Neumann 06 Bs=1 mG photodisint UHE nuclei propagation calculations log E [eV] • - simulation-based structured IGB models (also no IGB case) • source density ns~10-6 Mpc-3∝ baryon density • source power LCR(M)~ 3x1045 erg/s (fCR/0.1)(M/2x1015 MQ)5/3 • spectral index p=2, Emax(Z) from tacc vs. tloss, tlife • Galactic CR-like source composition (nFe/np~10-3 at fixed E/A) • CMB+FIRB losses, IGB deflections inc. all secondary nuclei

  14. spectra composition UHE nuclei from clusters: results with IGB fCR~0.03 no IGB fCR~0.005 1019 eV 1019 eV 1020 eV 1020 eV anisotropy • spectra, anisotropy, composition • consistent with current HiRes • but not AGASA? higher Bs? • predictions: • - “GZK” cutoff >1020 eV • - heavy dominant >1019 eV • - large scale aniso. toward • few nearby sources Auger, TA, EUSO

  15. “Galactic CR-like” (solar metallicity) metallicity outside clusters (warm-hot IGM filaments) source composition ~0.1 solar (X-ray absorption) Nicastro et al 05 ~0.2 solar (simulations) Cen & Ostriker astro-ph/0601008 nonlinear acceleration effects? rigidity selection (heavy enhancement) stronger effects for accretion shocks? hard spectra at high E p<~1.5 Kang & Jones 05 Drury, Meyer & Ellison 99

  16. UHE nuclei induced pairs and emission photopair 16O 56Fe Bs=0.1 mG lifetime escape Bs=1 mG photodisint nuclei photopair+photodisint. loss importantadditional hard X-ray and g-ray emission, broader spectra? Ee+e-,A ~ (me /Amp ) Z Ep Ee-,ndec ~ (mn-p /Amp ) Z Ep direct proof of nuclei acceleration constrain source composition potentially

  17. expected high energy emission from clusters summary • primary inverse Compton outskirts, MeV-GeV • p-p p0 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 e.g. non-gravitational energy injection, I & Nagashima, in prep. but very little neutrinos… new type of high energy source potentially very rich information fertile new field of high energy astrophysics (Renaixança)!

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