Physics of High-Energy Cosmic Rays

Michael Kachelrieß

NTNU Trondheim

CR spectrum

Michael Kachelrieß High-Energy Cosmic Rays

CR spectrum

for practically all energies only two informations:

exponent α of dN/dE ∝ 1/Eα

chemical composition

Michael Kachelrieß High-Energy Cosmic Rays

Why UHECR astronomy:

astronomy with HE photons restricted to few Mpc:

10−5 10−4 10−3 10−2 10−1 100 101 102 103

redshift z

7

8

9

10

11

12

13

14

15

16

log

10[E

/eV

]

10−5 10−4 10−3 10−2 10−1 100 101 102 103

7

8

9

10

11

12

13

14

15

16

Eew~ (GF)−1/2

Gal

acti

c C

ente

r

Mrk

501

star

fo

rmat

ion

pea

ks

star

fo

rmat

ion

beg

ins

γe γe

γp e+e

−p

γγ e+e

−

3K

IR

VIS

UV

ν−domain

Michael Kachelrieß High-Energy Cosmic Rays

Why UHECR astronomy:

astronomy with HE photons restricted to few Mpc:very small neutrino event numbers: <

∼few/yr for AUGER

103

102

10

1

10-1

1022102110201019101810171016

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

WB

max

0.2

CR flux

Michael Kachelrieß High-Energy Cosmic Rays

AUGER experiment:

Michael Kachelrieß High-Energy Cosmic Rays

AUGER experiment:

Michael Kachelrieß High-Energy Cosmic Rays

AUGER: Pampa + Detector

Michael Kachelrieß High-Energy Cosmic Rays

Standard picture

Galactic SNR produce observed CRs up to E ∼ 1017 eV

Michael Kachelrieß High-Energy Cosmic Rays

Standard picture

Galactic SNR produce observed CRs up to E ∼ 1017 eV

Fermi shock acceleration explains power-law 1/E2.2

Michael Kachelrieß High-Energy Cosmic Rays

Standard picture

Galactic SNR produce observed CRs up to E ∼ 1017 eV

Fermi shock acceleration explains power-law 1/E2.2

modified by energy dependent diffusion

Michael Kachelrieß High-Energy Cosmic Rays

Standard picture

Galactic SNR produce observed CRs up to E ∼ 1017 eV

Fermi shock acceleration explains power-law 1/E2.2

modified by energy dependent diffusion

extragalactic sources only above E ∼ 1019 eV

Michael Kachelrieß High-Energy Cosmic Rays

Three outstanding questions:

Is the standard picture correct?

Michael Kachelrieß High-Energy Cosmic Rays

Three outstanding questions:

Is the standard picture correct?

Is astronomy with UHECRs possible?

role of magnetic fieldsprotons vs nuclei as primaries

Michael Kachelrieß High-Energy Cosmic Rays

Three outstanding questions:

Is the standard picture correct?

Is astronomy with UHECRs possible?

role of magnetic fieldsprotons vs nuclei as primaries

Is physics beyond the SM needed to explain UHECR events?

energy spectrum consistent with GZK suppression?

suppression depends on number of sources, their minimal

distances, magnetic fields, . . .

correlations with sources at cosmological distances?

Michael Kachelrieß High-Energy Cosmic Rays

Energy losses, the dip and the GZK cutoff

1e-11

1e-10

1e-09

1e-08

1e-07

18 18.5 19 19.5 20 20.5 21 21.5

(1/E

)*d

E/d

t [1

/yr]

log10(E/eV)

pion production

pair production

redshift

at E ∼ 4×1019 eV:N + γ3K → ∆→ N +πstarts and reduces freemean path to∼ 20 Mpc

pair production leedsto a dip at ∼ 1019 eV

Michael Kachelrieß High-Energy Cosmic Rays

Cosmic ray spectrum: the dip at 1019 eV [Berezinsky, Grigorieva, Hnatyk ’04 ]

Michael Kachelrieß High-Energy Cosmic Rays

Transition to extragalactic protons

[Bere

zin

sky,

Grigorieva,H

naty

k’0

4]

Michael Kachelrieß High-Energy Cosmic Rays

Transition to extragalactic protons

[Bere

zin

sky,

Grigorieva,H

naty

k’0

4]

dip suggests: primaries above 1018 eV are extragalactic protons

Michael Kachelrieß High-Energy Cosmic Rays

Contradiction between shock acceleration and observed

spectrum?

1e+19

1e+20

1e+21

1e+18 1e+19 1e+20

E3 *F

(E)

[eV

2 cm

-2 s

-1 s

r-1]

E [eV]

HiRes I

HiRes II

n=10-5/Mpc3; β=1.7; 1/E2.0

n=10-5/Mpc3; same sources; 1/E2.7

n=inf; same sources; 1/E2.7

n=inf; same sources; 1/E2.0

Michael Kachelrieß High-Energy Cosmic Rays

Contradiction between shock acceleration and observed

spectrum?

good fit with just 2 free parameters, compatible with th.models

strong evidence for extragalactic protons above 1018 eV

is astronomy possible?

proton as primary necessary but not sufficient conditionstill depends on magnetic fields...

Michael Kachelrieß High-Energy Cosmic Rays

Deflections for eE/Q = 4×1019eV in the GMF:

0 2 4 6 8 10

Michael Kachelrieß High-Energy Cosmic Rays

Extragalactic magnetic field – simulation DGST:

Pavo

+

+

+

Centaurus

Virgo

10 2 3 4 5

+Coma

++

+ PerseusA3627

Hydra

0 [Degrees]

[Dolag, Grasso, Springel, Tkachev ’03 ]

Michael Kachelrieß High-Energy Cosmic Rays

Extragalactic magnetic field – simulation DGST:

DGST: astronomy with UHE protons possible in large part of sky!

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:

h12

+60

−60

−30

+30

0

o

o

o

o

h h24

GC

AGASA

C

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:correlation with certain source classes

(100 EeV)

(1 ZeV)

Neutronstar

Whitedwarf

SNR

Crab

E ~ ZBLmax

AGN

Protons

Collidinggalaxies

GRB

VirgoGalactic disk

halo

Clusters

RG lobes

1 au 1 pc 1 kpc 1 Mpc

-9

-3

3

9

15

3 6 9 12 15 18 21

x

log(Magnetic field, gauss)

β

log(size, km)

Fe (100 EeV)

Protons

x

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:correlation with certain source classes

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:correlation with certain source classes

estimation of general source properties (ns, L)

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:correlation with certain source classes

estimation of general source properties (ns, L)identification of acceleration mechanism

Michael Kachelrieß High-Energy Cosmic Rays

Examples for astronomical studies:

finding point sources:correlation with certain source classes

estimation of general source properties (ns, L)identification of acceleration mechanism

correlation with large-scale structure of sources

Michael Kachelrieß High-Energy Cosmic Rays

Example: Number density ns of sources

As ns decreases, sources become brighter for fixed flux ⇒probability for clustering increases [Waxman, Fisher, Piran ’96 ]

Michael Kachelrieß High-Energy Cosmic Rays

Example: Number density ns of sources

As ns decreases, sources become brighter for fixed flux ⇒probability for clustering increases. [Waxman, Fisher, Piran ’96 ]

Since NtotÀ Ncl, most sources are not seen:

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6

P_n(k

)

k-plets

Michael Kachelrieß High-Energy Cosmic Rays

Example: Number density ns of sources

As ns decreases, sources become brighter for fixed flux ⇒probability for clustering increases. [Waxman, Fisher, Piran ’96 ]

Since NtotÀ Ncl, most sources are not seen:

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6

P_n

(k)

k-plets

allows to estimate ns

Michael Kachelrieß High-Energy Cosmic Rays

Small-scale clusters and density of sources:

0.001

0.01

0.1

1

1e-07 1e-06 1e-05 1e-04 0.001 0.01

P

ns/Mpc3

➜ HiRes 68%

➜ HiRes 90%

➜ HiRes 99%

X-ray selected AGN⇐ ⇒

Michael Kachelrieß High-Energy Cosmic Rays

Medium-scale anisotropies in UHECRs:

1e-05

0.0001

0.001

0.01

0.1

1

0 20 40 60 80 100 120 140 160 180

P(δ

)

δ [degrees]

H 40 EeV 27A+ H 57

A+H+Y+S 101A+H+Y+S+HP+VR 106

all public + unpub

Michael Kachelrieß High-Energy Cosmic Rays

Multi-messenger astronomy:

HE photons and neutrinos are secondaries of CR interactions

Michael Kachelrieß High-Energy Cosmic Rays

Multi-messenger astronomy:

HE photons and neutrinos are secondaries of CR interactions

all three fluxes are related: e.g. CR flux bounds neutrino flux

Michael Kachelrieß High-Energy Cosmic Rays

Multi-messenger astronomy:

HE photons and neutrinos are secondaries of CR interactions

all three fluxes are related: e.g. CR flux bounds neutrino flux

all energy in γ and e± cascades down to MeV–GeV range,bounded by observations:

10-2

1

102

104

106

108 1010 1012 1014 1016 1018 1020 1022 1024

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

EGRET

FORTE

GLUE

MACROBaikal

AMANDA II

RICE

AGASA

Fly’s Eyeatm ν

γ

νi

p

[Semikoz, Sigl ’03 ]

Michael Kachelrieß High-Energy Cosmic Rays

Sensitivity of neutrino detectors

1

10

102

103

1012 1014 1016 1018 1020 1022

j(E)

E2 [e

V c

m-2

s-1

sr-1

]

E [eV]

γ-ray bound

MPR bound

WB bound

atm ν

ICECUBE

NUTEL

EUSO

ANITA 30 days

TA

RICE

AUGER

AMANDA-II, ANTARES

BAIKAL

atm ν

Michael Kachelrieß High-Energy Cosmic Rays

Summary I:

UHECR data will provide soon unique information about

structure of galactic magnetic field

magnitude of extragalactic magnetic fields

if both are “small”, astronomy with UHECRs will be possible

determination of source density ns

determination of source classes

acceleration mechanism?

if primary type is established, QCD studies with UHECRs will test

inelastic cross section, elasticity

QCD color-glas condensate

Michael Kachelrieß High-Energy Cosmic Rays

Summary II

Z bursts and topological defects can be only subdominantsources of UHECR

no positive evidence for superheavy dark matter from its twokey signatures:

photonsgalactic anisotropy

open questions for AUGER, Anita, . . . :

clustering due to point sources?

correlations with BL Lacs?

existence of GZK suppression?

photons as primaries?

detection of UHE neutrinos: opens a new window to theUniverse

Michael Kachelrieß High-Energy Cosmic Rays