Gamma-Rays and UHE Cosmic Rays

from Clusters of GalaxiesSusumu Inoue

(Nat. Astron. Obs. Japan)and collaborators

GeV100keV

HESS Auger

GLASTSuzaku

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-rayFusco-Femianoet al. 04

Rossetti &Molendi 04

4.8 detection

no detection

gamma-ray no clear evidence yet!GeV Reimer et al. 03

EUV

Bowyeret al. 04

TeV Perkins et al. 06

Renaud et al. astro-ph/0606114

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.+ICc.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

tIC<<tshock

tloss, tconf>>tH

11

10

9

8

720.520.019.519.018.518.017.5

log E [eV]

UHE proton-induced pair emission from cluster accretion shocks

accel. vs CMB losses, lifetime

photopion

lifetimeescape accel.

Bs=0.1 G

photopair

accel.Bs=1 G

e.g. Coma-like clusterM=2x1015 M(T=8.3 keV)WMAP cosmo. parameters

Inoue, Aharonian & Sugiyama 2005 ApJ 628, L9proton Emax

c.f. Kang, Rachen & Biermann 97

Rs~3.2 MpcVs~2200 km/sBs,eq~ 6 G

Emax~1018-1019 eVphotopair important

tacc=(20/3) rgc/Vs2

shock radius, velocity, etc.

Bohm limit shock accel. time

SNR observations ~1e.g. Völk et al. 05

escape timetesc~R2/D(E=Emax)~R/V~2 Gyr shock lifetimetsl~R/V~2 Gyr < tadiab~6 Gyr

proton injection luminosity in accretion shocks

accretion rate & luminosityM(M,z)=fgasfaccVs

3/GLacc(M,z)=fgasfaccGMM/Rs

~2.7x1046 (fgas/0.16) (facc/0.1) (M/ 2x1015 M)5/3 erg/s

proton 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. 03

secondary production and emission processes

p+CMB→ p+ e+e-

Ep~1018eV E+-~+-Ep~1015eV→ 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 Mpcsensitivities for 1 deg2 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, NeXTHESS, MAGIC,CANG.3, etc.

5 100h

cascade emission: pair “halo”

pre-“absorbed” fluxcascade 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 94Coppi & Aharonian 97

3. UHECRs from cluster accretion shocks?

Norman, Achterberg & Melrose ‘95Kang, Ryu & Jones 96Kang, Rachen & Biermann 97

GRB

AGN jet

clusters

energetic requirements

Lcluster~1046 erg/sncluster~10-6 Mpc-3

Pcluster~~1040 erg s-1Mpc-3

UHECR@1020 eVuCR ~10-20 erg cm-3

CR ~0.3(1) Gyr for p (Fe)PCR ~3x1037 erg s-1Mpc-3 massive clusters (~1015 M)

energetically plausiblebut proton Emax insufficient

oblique shocks do not helpOstrowski & Siemieniec-Ozieblo 00

“Hillas plot” adapted fromYoshida & Dai 98

UHECRs: energy losses during propagation

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p+CMB→ p+ e+e- Ep>~5x1017eVp+CMB→ p+ Ep>~7x1019eV

Lp, 20eV <~100 Mpc

A+CMB→ A+ e+e-

A+FIRB→ A-iN +iNNagano & Watson 00

Fe

p

E

Lloss

LFe, 20eV <~300 Mpc

protons: photopair+photopion

nuclei: photopair+photodisint.

e.g. Stecker &Salamon 99

E>2x1019 eV no data at all (too low statistics)E<2x1019 eV light dominant but greater uncertainties than commonly believed?

current data on composition HiRes stereo Xmax

Watson astro-ph/0408110

nuclei from cluster accretion shocks as UHECRs

107

108

109

1010

1011

1018

2 3 4 5 6

1019

2 3 4 5 6

1020

2 3 4 5 6

1021

log E [eV]

56Fe

photodisint

photopair

Bs=0.1 G

Bs=1 G

heavy nuclei Emax

for Bs~1 G, EFe, max>~1020 eV

Inoue, Sigl, Armengaud & Miniatiin prep.

UHE nuclei propagation calculations

56Fe

lifetimeescape

log E [eV]lo

g t ac

c, t lo

ss [y

r]

Bs~1 G Johnston-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 M)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

Feretti & Neumann 06

UHE nuclei from clusters: results

with IGB

no IGB

spectra composition

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, EUSO

1020 eV1019 eV 1019 eV 1020 eV

fCR~0.03

fCR~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/0601008

UHE nuclei induced pairs and emission

107

108

109

1010

1011

1018

2 3 4 5 6

1019

2 3 4 5 6

1020

2 3 4 5 6

1021

log E [eV]

56Fe

photodisint

photopair

Bs=0.1 G

Bs=1 G

107

108

109

1010

1011

1018

2 3 4 5 6

1019

2 3 4 5 6

1020

2 3 4 5 6

1021

log E [eV]

16O

nuclei photopair+photodisint. loss importantadditional hard X-ray and -ray emission, broader spectra?

56Fe16O

lifetimeescape

direct proof of nuclei accelerationconstrain source compositionpotentially

Ee+e-,A ~ (me /Amp ) Z Ep Ee-,ndec ~ (mn-p /Amp ) Z Ep

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, locationpotential probe of cluster evolution

new type of high energy sourcepotentially very rich informationfertile new field of high energy astrophysics (Renaixança)!

e.g. non-gravitational energy injection, I & Nagashima, in prep.

but very little neutrinos…