銀河団における超高エネルギー物理過程

1. 井上 進 (国立天文台) 銀河団における超高エネルギー物理過程 UHE proton induced hard X-rays & g-rays w. Felix Aharonian (MPIK), 杉山直 (国立天文台) w. Günter Sigl, Eric Armengaud (IAP)Francesco Miniati (ETH) UHE cosmic ray nuclei GLAST Suzaku GeV 100 keV Auger HESS TeV ZeV

2. 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

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) clusters Lcluster~1046 erg/s ncluster~10-6 Mpc-3 Pcluster~~1040 erg s-1Mpc-3 energetically plausible, but proton Emax insufficient

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

5. Coma-like cluster at D=100 Mpc > TeV absorption by IRB, CMB emitted flux & detectability sensitivities for 1 deg2 extended source • large radiative efficiency from protons- hard (G~-1.5) spectrum + rollover- sensitive to B <-> primary IC, pp p0 (G~-2)

6. coming very soon!!! TeV g-ray and hard X-ray observations of clusters • Inoue, Gabici, Aharonian & Rowell, HESS proposal, accepted • Inoue, Nakazawa, Fukazawa et al., Suzaku proposal, submitted Suzaku X also expecting contributions from CANGAROO III X g HESS g

7. Inoue, Sigl, Armengaud & Miniati, in prep. nuclei from cluster accretion shocks as UHECRs photopair maximum E for heavy nuclei 56Fe photopair+photopion CMB photodisint FIRB+CMB Bs=0.1 mG lifetime escape if Bs~1 mGEFe, max>~1020 eVphotopair important Johnston-Hollitt & Ekers ‘05 Bs~1 mG Bs=1 mG photodisint UHE nuclei propagation calculations • - realistic IGB models based on cosmological simulations • source density ~10-6 Mpc-3∝ baryon density • Emax(Z) from tacc vs. tloss, tlife • Galactic CR-like source composition (nFe/np~0.05) • interactions in CMB+FIRB, deflections in IGB • including all secondary nuclei

8. spectra composition UHE nuclei from clusters: results with IGB no IGB anisotropy • spectra, anisotropy, composition • consistent with • current HiRes but not AGASA… • predictions: • - “GZK” cutoff >1020 eV • - heavy dominant >1019 eV • - one or few extended source(s) • >4x1019eV

9. UHE nuclei induced pairs photopair 16O 56Fe Bs=0.1 mG lifetime escape Bs=1 mG photodisint photopair importantadditional hard X-ray and g-ray emission, broader spectradirect proof of nuclei acceleration in cluster accretion shocks

10. UHE processes in cluster accretion shocks UHE p-induced emission summary • acceleration to E~1018-1019eV • efficient secondary pair emission • -> hard X sync. Suzaku, NeXT (imaging), … • -> TeV IC HESS, CANG.III, other current IACTs • important probe of UHE p acceleration, B in cluster outskirts, … stay tuned for upcoming HESS & Suzaku observations! UHECR nuclei • Fe acceleration to E~1020eV plausible if B~1 mG • UHECR flux and spectra consistent if nFe/np~0.05 at source • predictions for Auger,TA,EUSO: • - spectra: cutoff >~1020 eV • - composition: p dominant ~<1019 eV, Fe dominant >~1020 eV • - anisotropy: a few extended sources >~4x1019 eV • additional hard X/TeV from pairs HESS, Suzaku, …

11. proton injection luminosity in accretion shocks . 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 . proton luminosity & spectrum Lp(M,z)=fpLacc(M,z) fp=0.1 Fp(E,M,z) ∝ E-2 exp(-E/Emax) secondary production and emission processes p+gCMB→ p+ e+e-Ep~1018eV E+-~k+-Ep~1015eV, L+-~t+-/tinj f(E>1017.7eV) Lp →e+e-+B(~mG)→ syn. Eg~keV-MeV e+e-+gCMB→ IC Eg~TeV-PeV Aharonian 02 code solve proton & pair kinetic eq.

12. sensitivities for 1 deg2 extended source model vs Coma data - hard X? need large p luminosity - radio something else hard X data <1 deg

13. UHECRs: energy losses during propagation p+gCMB→ p+ e+e- Ep>~5x1017eVp+gCMB→ p+ p Ep>~7x1019eV Dp, 20eV <~100 Mpc A+gFIRB→ A+ e+e-A+gFIRB→ A-iN +iN

14. models based on cosmological simulations Sigl, Miniati & Ensslin 03,04 intergalactic B fields 1. shock generation 2. uniform seed normalized to cluster magnetic fields source distribution Ns=10-6 Mpc-3, ∝ baryon density randomly distribute, many realizations

15. “Galactic CR-like” observed Galactic CR at high E further enhanced? Fe/p~1/4 @1015eV observed Galactic CR at low E heavy elements enhanced, Fe/p~0.1 source composition Sigl & Armengaud 05 Hoerandel 05 observed metallicity at cluster outskirts ~0.1 solar Finoguenov et al 03

16. Watson astro-ph/0408110 current data on UHE composition • - E>2x1019 eV: no data at all! (too low statistics) • E<2x1019 eV: much greater uncertainties than often advertised

17. With field: Isotropy consistent with current statistics Without field: probably too anisotropic due to low source density Significant anisotropy should appear for > 1000 events above 4x1019 eV. No anisotropy for ~100 events above 4x1019 eV. for 1 particular realization results: sky map