銀河団における超高エネルギー物理過程

w. Felix Aharonian (MPIK), 杉山直 ( 国立天文台 ) 井上 進 ( 国立天文台 )

w. Günter Sigl, Eric Armengaud (IAP)Francesco Miniati (ETH)

ZeV

GeV

TeV

100keV

HESS Auger

GLASTSuzaku

UHE proton inducedhard X-rays & -raysUHE cosmic ray nuclei

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

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 plausible, butproton Emax insufficient

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

Rs~3.2 MpcVs~2200 km/s

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

Bs,eq~ 6 G

Emax~1018-1019 eVphotopair important

tacc=(20/3) rgc/Vs2

shock radius, velocity, etc.

Bohm limit shock accel.

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

shock lifetimets~2 Gyr < tadiab~6 Gyr

max p energy

Inoue, Aharonian & Sugiyama 2005 ApJ 628, L9

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

<-> primary IC, pp 0

(~-2)

> TeV absorption by IRB, CMB

• Inoue, Gabici, Aharonian & Rowell, HESS proposal, accepted

HESS

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coming very soon!!!

Suzaku

X

X

TeV -ray and hard X-ray observations of clusters

• Inoue, Nakazawa, Fukazawa et al., Suzaku proposal, submitted

also expectingcontributions fromCANGAROO III

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]

56Fephotopair+photopion CMBphotodisint FIRB+CMB

photodisint

photopair

Bs=0.1 G

Bs=1 GBs~1 G Johnston-Hollitt & Ekers ‘05

maximum E for heavy nuclei

if Bs~1 GEFe, max>~1020 eVphotopair important

Inoue, Sigl, Armengaud & Miniati, in prep.

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

56Fe

lifetimeescape

UHE nuclei from clusters: results

with IGB no IGB

spectra composition

anisotropyspectra, 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

UHE nuclei induced pairs

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 56Fe16O

lifetimeescape

photopair importantadditional hard X-ray and -ray emission, broader spectradirect proof of nuclei acceleration in cluster accretion shocks

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, …

UHE p-induced emission

stay tuned for upcoming HESS & Suzaku observations!

UHECR nuclei

• Fe acceleration to E~1020eV plausible if B~1 G• 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, …

UHE processes in cluster accretion shocks

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/sproton luminosity & spectrumLp(M,z)=fpLacc(M,z) fp=0.1Fp(E,M,z) ∝ E-2 exp(-E/Emax)

secondary production and emission processesp+CMB→ p+ e+e-

Ep~1018eV E+-~+-Ep~1015eV, L+-~t+-/tinj f(E>1017.7eV) Lp

→ e+e-+B(~G)→ syn. E~keV-MeV e+e-+CMB→ IC E~TeV-PeV

Aharonian 02 code solve proton & pair kinetic eq.

..

model vs Coma data

- hard X? need large p luminosity- radio something else

sensitivities for 1 deg2 extended source

-15

-14

-13

-12

-11

-10

1050-5

log E [eV]

Lp=9x1045

erg/sTinj=4 Gyr, Rs=3.2 MpcBs=0.7 (G Emax=6.3 10x 18 )eV

=10n -6 cm-3

=100 D Mpc

EUVERXTE

EGRET

GLASTHESS

HXDNeXTHXI

NeXTSGD

e+e- syn e+e- IC

pp0

BSAX

hard X data <1 deg

UHECRs: energy losses during propagation

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

Dp, 20eV <~100 Mpc

A+FIRB→ A+ e+e-

A+FIRB→ A-iN +iN

intergalactic B fields models based oncosmological simulations

Sigl, Miniati& Ensslin 03,04

1. shock generation 2. uniform seed

normalized to cluster magnetic fields

source distributionNs=10-6 Mpc-3, ∝ baryon densityrandomly distribute, many realizations

source composition

Sigl & Armengaud 05

observed Galactic CR at low Eheavy elements enhanced, Fe/p~0.1

observed Galactic CR at high Efurther enhanced? Fe/p~1/4 @1015eV

Hoerandel 05

“Galactic CR-like”

observed metallicityat cluster outskirts~0.1 solar

Finoguenov et al 03

current data on UHE composition Watson astro-ph/0408110

- E>2x1019 eV: no data at all! (too low statistics)- E<2x1019 eV: much greater uncertainties than often advertised

With field:Isotropy consistentwith current statistics

Without field: probablytoo anisotropic due tolow source density

No anisotropy for ~100 eventsabove 4x1019 eV.

Significant anisotropy shouldappear for > 1000 eventsabove 4x1019 eV.

for 1 particular realizationresults: sky map