Gamma-Rays and UHE Cosmic Rays from Clusters of Galaxies

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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. - PowerPoint PPT Presentation


  • Gamma-Rays and UHE Cosmic Raysfrom Clusters of GalaxiesSusumu Inoue(Nat. Astron. Obs. Japan)and collaboratorsGeV100keVHESSAugerGLASTSuzakuZeVTeV

  • outline1. introduction2. gamma-ray emission from clusters3. UHE cosmic rays from clusters- UHE proton - photon pair syn.+IC- UHE cosmic ray nuclei (and photopairs)I, Aharonian & SugiyamaI, Sigl, Armengaud & Miniati- cascading (pair halo)I, Coppi & AharonianMulti-messenger-nisme

  • current evidence for nonthermal emission: Coma1. introductionradioGiovannini et al. 93hard X-rayFusco-Femianoet al. 04Rossetti &Molendi 044.8s detectionno detectiongamma-rayno clear evidence yet!GeV Reimer et al. 03EUVBowyeret al. 04TeV Perkins et al. 06Renaud et al. astro-ph/0606114

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

  • cluster accretion shocksRyu et al. 03strong (high M) shock-> high injection, hard spectraweak (low M) shock-> low injection, soft spectracrucial for nonthermal high energy phenomena

  • nonthermal high energy emission from clustersMiniati 03thermal>100 MeV>100 keV primary electron IC LE proton p+p->p0 UHE proton-induced pair syn.+ICc.f. Aharonian 02 Rordorf, Grasso & Dolag 04traces shocktraces gase.g. Waxman & Loeb 00 Totani & Kitayama 00e.g. Vlk et al. 96 Berezinsky et al. 97tICtH

  • UHE proton-induced pair emission from cluster accretion shocksaccel. vs CMB losses, lifetimephotopionlifetimeescape accel.Bs=0.1 mGphotopair accel.Bs=1 mGe.g. Coma-like clusterM=2x1015 MQ(T=8.3 keV)WMAP cosmo. parametersInoue, Aharonian & Sugiyama 2005 ApJ 628, L9proton Emaxc.f. Kang, Rachen & Biermann 97Rs~3.2 MpcVs~2200 km/sBs,eq~ 6 mGEmax~1018-1019 eVphotopair important tacc=(20/3) h rgc/Vs2shock radius, velocity, etc.Bohm limit shock accel. timeSNR observations h~1e.g. Vlk et al. 05escape timetesc~R2/D(E=Emax)~R/V~2 Gyr shock lifetimetsl~R/V~2 Gyr < tadiab~6 Gyr

  • proton injection luminosity in accretion shocksaccretion rate & luminosityM(M,z)=fgasfaccVs3/GLacc(M,z)=fgasfaccGMM/Rs ~2.7x1046 (fgas/0.16) (facc/0.1) (M/ 2x1015 MQ)5/3 erg/sproton luminosity & spectrumLp(M,z)=fpLacc(M,z) fp=0.1Fp(E,M,z) E-2 exp(-E/Emax)facc=0.1 normalized from simulationKeshet et al. 03secondary production and emission processesp+gCMB p+ e+e-Ep~1018eV E+-~k+-Ep~1015eV e+e-+B(~mG) syn. Eg~keV-MeV e+e-+gCMB IC Eg~TeV-PeVAharonian 02 solve proton & pair kinetic eq...

  • emitted flux & detectability Coma-like cluster at D=100 Mpcsensitivities for 1 deg2 extended source large radiative efficiency from protons- hard (G~-1.5) spectrum + rollover- sensitive to Bc.f. primary IC, pp p0 (G~-2)> TeV absorption by IRB+CMBSuzaku, NeXTHESS, MAGIC,CANG.3, etc.5s 100h

  • cascade emission: pair halopre-absorbed fluxcascade down to GeV-TeVcluster pair halos- isotropic (much stronger than beamed sources)- hard spectrumalso for p-p p0 from coreprobe of IRB, TeV-PeV powerAharonian, Coppi & Vlk 94Coppi & Aharonian 97

  • 3. UHECRs from cluster accretion shocks?Norman, Achterberg & Melrose 95Kang, Ryu & Jones 96Kang, Rachen & Biermann 97GRBAGN jetclustersenergetic requirementsLcluster~1046 erg/sncluster~10-6 Mpc-3Pcluster~~1040 erg s-1Mpc-3 UHECR@1020 eVuCR ~10-20 erg cm-3tCR ~0.3(1) Gyr for p (Fe)PCR ~3x1037 erg s-1Mpc-3 massive clusters (~1015 MQ)energetically plausiblebut proton Emax insufficientoblique shocks do not helpOstrowski & Siemieniec-Ozieblo 00Hillas plotadapted fromYoshida & Dai 98

  • UHECRs: energy losses during propagationp+gCMB p+ e+e- Ep>~5x1017eVp+gCMB p+ p Ep>~7x1019eVLp, 20eV
  • nuclei from cluster accretion shocks as UHECRsphotodisintphotopairBs=0.1 mGBs=1 mGheavy nuclei Emaxfor Bs~1 mG, EFe, max>~1020 eVInoue, Sigl, Armengaud & Miniatiin prep.UHE nuclei propagation calculations 56Felifetimeescapelog E [eV]log tacc, tloss [yr]Bs~1 mGJohnston-Hollitt & Ekers 05- 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 nucleiFeretti & Neumann 06

  • UHE nuclei from clusters: results with IGB no IGBspectracomposition anisotropyspectra, 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, EUSO1020 eV1019 eV1019 eV1020 eVfCR~0.03fCR~0.005

  • source compositionGalactic CR-like (solar metallicity)metallicity outside clusters (warm-hot IGM filaments)hard spectra at high E p
  • UHE nuclei induced pairs and emissionphotodisintphotopairBs=0.1 mGBs=1 mGnuclei photopair+photodisint. loss importantadditional hard X-ray and g-ray emission, broader spectra?56Fe16Olifetimeescapedirect proof of nuclei accelerationconstrain source compositionpotentiallyEe+e-,A ~ (me /Amp ) Z EpEe-,ndec ~ (mn-p /Amp )Z Ep

  • summaryexpected high energy emission from clusters 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-ZeVdifferent components dominate at different energy, locationpotential probe of cluster evolutionnew type of high energy sourcepotentially very rich informationfertile new field of high energy astrophysics (Renaixana)!e.g. non-gravitational energy injection, I & Nagashima, in prep.but very little neutrinos


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