Origin of Ultra High Energy Cosmic Rays

Susumu Inoue (NAOJ)

AGNs GRBs

clusters

astro-ph/0701835 (brief review)

collaborators:G. Sigl (APC), F. Miniati (ETH), E. Armengaud (CEA)F. Aharonian (MPIK), N. Sugiyama (Nagoya)

K. Asano (NAOJ)

Astrophysical Sources, Gamma-Ray Connection

outline1. general aspects

2. physics of selected UHECR source candidates

III. cluster accretion shocks

I. AGNs

II. GRBs

UHECR nuclei

source candidates: acceleration & energetics

UHE p-induced X/-rays

GeV-TeV -rays

propagation: extragalactic radiation and B fields

neutrinos -> Halzen

different AGN types

UHECR-induced secondary X/ radiation signatures

The problem:

UHECRs are the highest energy particlesobserved in the universe, exceeding 1020 eV.Their origin is unknown.

Emax~ 3x1020 eV ~50J ~kinetic E of 100km/h fastball (220km/h tennis serve)

UHECR observationsspectrum at least up to 1020 eV

arrival directions

composition light dominantup to ~<2x1019 eV?

>1020 eV X max [g

cm

-2]

globally isotropicno ID with sources

AGASA

HiRes

before July (ICRC) 07observations -> Kampert

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

Watson astro-ph/0408110nuclei possible at the highest E!

Anchordoqui+, Allard+, Armengaud+, …

(Greisen-Zatsepin-Kuzmin limit)

extragalactic B fields

Sigl, Miniati & Ensslin 03,04

should be correlated with large scale struc.

Dolag+ 04, 05Brüggen+ 05

crucial differences between theoretical models

very uncertain observationallyand theoretically

Galactic B fields also uncertain

Kang+ 07 propagation -> Das

secondary photon/neutrino signaturesdesirable to pinpoint sources!

top-down models: very strongly constrainedtopological defects, EHE Z-bursts, UHECRons, superheavy DM…

Yamamoto+ arXiv: 0707.2638Auger spectrum

spectral steepening at E>1019.6 eV(6 sigma)

also claimed by HiRes

Auger photon limitsSemikoz+ arXiv: 0706.2690

superheavy DM ruled out

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UHECR sources: acceleration

GRBs

AGN jets

clusters

adapted fromYoshida & Dai 98

R

B

B~∝R-1

“Hillas plot”E ≦ Ze B R (v/c)confinement

acceleration vs:Emaxescapesource lifetimeadiab. expansion lossradiative loss

shock acceleration

- power-law spectrum dN/dE~∝E-2 for strong shock- very efficient up to ~50% of kinetic energy

shock frontupstream downstream

consistent with observations- in-situ: earth-solar wind, …- SNRs, radio galaxy hot spots, …

acceleration -> Berezhko

UHECR sources: energy budget

differential (per unit z)dEkin/dz=(dt/dz)∫dL L dn/dL

UHECR budgetuCR ~3x10-19 erg cm-3

~1054 erg Mpc-3

kinetic E input into the universe

supernovae, GRBs

@1019 eV

AGNs (radio galaxies)z-dep. LF Willott+ 01Lkin-Lrad correlation Rawlings 92

∝ star formation rate Porciani &Madau 01

cluster accretion

Lacc(M)~0.9x1046 (M/1015 M)5/3 erg/sPress Schechter mass function

Keshet+ 04

EGRB=1053 erg, indep. of beamingESN=1051 erg

59

58

57

56

55

54

543210

z

radio galaxies supernovae gamma-ray bursts accretion

12

131415

GeV blazaractive galactic nuclei (AGNs)supermassive black hole+accretion disk (flow)

radio-quiet(no jet)

radio-loud(relativistic jet)

FR IIradiogalaxy

FR Iradiogalaxy

TeV blazar(BL Lac)

Seyfert galaxy

low-power

high-power

radio-quiet quasar

activity timescales~107-108 yr~<UHECR delay time

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~90%~9%

~<1%

AGNs: acceleration sites

from Chandra webpage

Seyfert or radio-quiet quasar near-nucleus?R~1013-1014 cm B~104G?Emax~Ep~<1018eV

e.g. Szabo & Protheroe 94

UHECR accel.not expected

inconsistent withobserved keV-MeV

AGNs: acceleration sites

inner jet (blazar)R~1016-1017 cm B~0.1-1G

from Chandra webpage

Emax~Ep~<1020eVe.g. Mannheim 93

low power (FR I) radio galaxy near-nucleus?

adiabatic loss -> n conversion escape?

shear-layer acceleration?

accel./escape non-trivial

UHECR accel.not expected

AGNs: acceleration sites

inner jet (blazar)

hot spot R~1021 cm B~1mG

from Chandra webpage

Emax~Ep~<1020eV

Emax~Eesc~1020-21eVe.g. Rachen & Biermann 93

high power (FR II) radio galaxy near-nucleus?UHECR accel.not expected

accel./escape non-trivial

accel./escape easiest

AGNs: anisotropy expectations?

Takami+ 06

anisotropy expectationsfor different AGN types

Takami, SI+, in prep.

ns=5x10-6 Mpc-3

AGNs: UHECR-induced secondary emission

Aharonian 02

Armengaud, Sigl & Miniati 05

proton synchrotron from hot spots/knots

“GZK” radiation from intracluster AGNs

GRBs internal + external (forward + reverse) shocks

adapted from Meszaros 01

prompt X- emission

internal shocks

optical flash, radio flare

external reverse shock

radio-IR-opt-X afterglow

external forward shock

Waxman 95, Vietri 95UHECR accel. site

Gialis & Pelletier 03Wick, Dermer & Atoyan 04

GRBs as UHECR sources Waxman & Miralda-Escude 96

time delayt(Ep,D)~2D/4c ~107 yr Ep,20

-2 D100Mpc2lMpcB-8

2

individual sources->narrow spectrum at given time

GRBs: GeV-TeV signature of UHECRs Asano & InoueApJ, in pressarXiv:0705.2910

inverse Compton proton synchrotron

- electrons+protons in internal shocks (prompt phase)- pair cascading, p interactions, various radiative processes…- parameters: Esh, t, , fB=uB/ue, assume up=ue, pp=2

GRBs: GeV-TeV signature of UHECRs

secondary pair synchrotron+ muon synchrotron+

double (multiple) breaks-> proton signature

GLAST, MAGIC (II), HESS (II), VERITAS, CANG.III …MILAGRO, Auger…

cluster accretion shocks

accretion(minor merger)

Ryu+ 03

strong shocks

Kang, Rachen, Biermann 97

Fe nuclei (Z=26) EFe, max>~1020 eV

Ep, max~ 1018-1019 eVprotons

if Bs~1 GHOWEVER

Mach no.

nuclei from cluster accretion shocks as UHECRs

heavy nuclei Emax

for Bs~1 GEFe, max~1020 eV

Inoue, Sigl, Miniati & Armengaud, PRL submitted (astro-ph/0701167)

Hubble

escape limittesc~R2/5(E)Emax/Z~7x1018 eV

acceleration vs CMB losses, lifetimeEmax

Rs~3.2 MpcVs~2200 km/s

tacc=(20/3) rgc/Vs2

shock radius, velocity, etc.

Bohm limit shock accel. time

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UHECRs as nuclei from clusters

with EGMF

no EGMF

spectrum

composition

anisotropy

1019 eV 1020 eV

fCR~0.005-0.3

fCR~0.002

SI, Sigl, Miniati, ArmengaudPRL, submitted(astro-ph/0701167)

consistent with current data(spectrum <2 sigma)with some heavy enhancement

clear predictions forAuger, Telescope Array, JEM-EUSO…

100 events>4x1019eV

1000 events>4x1019eV

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composition Unger+ arXiv: 0706.1495

mixed compositionat all E

becoming heavierat highest E?

UHE proton-induced hard X+ emission from clusters

Suzaku?NeXT, Simbol-X, NuSTAR

HESS, MAGIC,CANG.3, VERITAS…

SI, Aharonian, Sugiyama 05

ComaD=100 Mpc

p(1019eV) +CMB→ p+ e+e- (1016eV)

e+e-+B(~G)→keV, e+e-+CMB→TeV

summary

cluster accretion shocks (nuclei)

characteristic spectra, anisotropy, composition hard X-rays + TeV gamma-rays

AGNs

GRBstight energy budget

characteristic GeV-TeV signatures

consistent for some enhancement in heavy composition

other sources?starburst galaxies …Galactic NS, magnetars …

none of these?

different likelihood for different types high-power RG > low-power RG > radio-quiet

concluding haiku

「松島や　ああ松島や　松島や」　松尾芭蕉（？）

“Matsushima, ah Matsushima, Matsushima.” - Matsuo Basho (?)

宇宙線　ああガンマ線　ニュートリノ

“Cosmic rays, ah Gamma-rays, Neutrinos.”

The real beauty will be in the combination of the techniques!