interpretation of cosmic ray spectrum above the knee measured...

Interpretation of cosmic ray spectrum above the knee

measured by the Tunka-133 experiment

L.G. Sveshnikova, L.A. Kuzmichev, E.E. Korosteleva, V.A. Prosin, V.S. Ptuskin

et al Moscow State University Skobeltsyn Institute of Nuclear physics

Outline

• Problems

• Tunka 25,133 method and results

• Comparison with other experiments

• Theoretical model of sources and Emax

• Origin of the Knee and transition region to Metagalactic

• Сonclusions

Figure from V. Ptuskin, V. Zirakashvili, and

Eun-Suk Seo, Astrophysical J. T. 718 p.

31–36. 2010 .

From the theory we can expect the sequence of different types of dominating sources in

different energy intervals and only a small number can accelerate to highest energies

due to high value of required magnetic field and shock speed. Only very specific

conditions of explosions and progenitor’s history allows to get large Emax.

IIp Ibc Ia ? or IIb IIb? GRB?

100 TeV 1PeV 4 PeV 60 PeV

Transition from one type of dominating sources to other should reveals itself

as a features in spectrum: knee , dip, peak.. So precise measurement of all

particle spectrum and of partial nuclei spectra continue to be very important

task.

Problem

PeV accelerated particle escape from SNR at 10-100 years after explosion,

so a chance to see directly gamma quanta from pevatron is very small.

R= 1 km

175 optical detectors (EMI 9350) covering an area of 3 km2

In operation since 2009

Tunka-133 a 3 km2 Air Cherenkov Light Array

50 km from Lake Baikal, in Siberia

Single detector: We measure the next parameneters of Cherenkov

photon pulse through 5 ns: Q=c∙Spulse, Amax, dt=, ti time

delay with accuracy nsec

ti

Spulse

Amax

anode:

dinode:

Width of pulse

Lateral distribution is approximated by 4 functions in every shower and Q200 and

steepness parameter b is estimated

A(R) =

A(400)·((R/400+1)/2)-b

A(R) = A(400)·((R/400+a)/(a+1))-b

A(R) = Akn·exp((Rkn-

R)·(1+3/(R+2))/R0)

A(R) = Akn·(Rkn/R)c

Recalculation from Cherenkov light flux Q200 to the primary energy E0

E0 = A·Q200g

g = 0.94

CORSIKA simulation:

protons

iron nuclei

Zenith angles: 0°, 30°, 45°

As a measure of energy we use the

Cherenkov light flux density at a core

distance of 200m - Q(200). It was found

from CORSIKA.

First method of Xmax reconstruction by parameter b

∆Xmax = 2767 - 3437∙log10(bA-2),

g∙cm-2

Dependence of the relative

EAS maximum position Xmax

on log (b − 2)

Dis

tance to the m

axim

um

of show

er

Second method of Xmax reconstruction from width of pulse,(400m), “width-distance method”

The -method uses the sensitivity

of the pulse width at some fixed

core distance to the position of the

EAS maximum.

This function was constructed

on the basis of CORSIKA

simulation

the value of ( 400) is connected

with the thickness of the

atmosphere between the detector

and Xmax

(Xmax = X0/cos − Xmax) by the

expression:

Xmax = C − D · log e f f (400).

Dis

tance to the m

axim

um

of show

er

Log Pulse Width at 400 m

Best fit (solid) for two different energy bins. The lines correspond to:

proton (red dash), helium (pink), nitrogen (dagreen) and iron (blue).

Xmax distribution in every energy bin was fitted as a superposition of weighted

elemental distribution of 4 groups: p, He, CNO and Fe.

For this analysis, partial Xmax distributions were simulated using CORSIKA 7.35

(2013) with QGSJETII-04/GHEISHA (S.N.Epimakhov et al. (Tunka Collaboration),

33th ICRC, Julym 2013.397 ID=0326.)

Distribution of Xmax in every energy interval is converted to partial spectra P, He, CNO, Fe

Experimental data

3 winter seasons of operation 2009-2010 , 2010-2011, 2011-2012

1000 houre of good wether observation

~ 6 000 000 triggeres

For the analysis of mass composition only events with

θ ≤ 40°, Rcore < 500 m:

~ 170 000 showers with E0 > 6·1015 eV – 100% efficiency

~ 60 000 events with E0 > 1016 eV

~ 600 events with E0 >1017 eV

Doi

http://dx.doi.org/10.1016/j.nima.2013.09.018

1 knee hardening 2 knee

In press




Spectra of P, He, CNO, Fe components

Systematic errors are large !!


Kascade Grande W.D. Apel et al. [KASCADE-Grande Collaboration], Phys.

Rev. D 87, 402 081101(R) (2013)

Tunka: http://dx.doi.org/10.1016/j.nima.2013.09.018

Comparison of light and heavy components with Kascade – Grande : nuclei separation by Xmax in

Tunka versus muon content of showers in KG




Comparison with other experiments: agreement

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-1,00

-0,75

-0,50

-0,25

0,00

0,25

0,50

Structure=F(E)/AE-3-1

Str

=F

(E)/

AE

3-1

E, GeV

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106

1,5x106

2x106

2,5x106

3x106

IxE

3.0 m

-2 s

-1 sr-

1 G

eV

1.7

5

En, GeV

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-0,4

-0,2

0,0

0,2

0,4

Structure F(E)/AE-3 -1

Str

uctF

(E)*

E1

E GeV

Tibet 3 models

Gamma Ice Top 2013

Tunka 133(2012), Kascade-Gr.

Comparison:

Common features

1. Sharpness and position of the knee at 4 PeV

2. Sharpness and position of the inverse knee (hardening) at 20 PeV

3. Sharpness and position of the second knee at 100 or 300 PeV

(Tunka: 2 knee `300 PeV, Kascade Gr ~ closer to 100 PeV)

Features: knees, dips, peaks

How they can be produced?

32 ICRC, 2012, Beijing

100

101

10-2

10-1

100

Hoerandel 1 TeV : P+He=60%: 0.20,0.40, 0.13,0.13,0.13

Hoerandel 1 TeV : P+He=60%: 0.30,0.30, 0.13,0.13,0.13

In

teg

ral sp

ectr

um

by Z

:N>

Z

Z

d=lg(IFe/Itot)/lg 26 ~ d ~0.6 (if Fe 13%) d~ 0.5 (if Fe~20%)

Regidity dependent cutoff: Emax(Z)=ZEmax(H)

Change of gamma

by 0.5-0.6

corresponds to

“normal

composition”

Integral abundance I(>Z)

d=0.5-0.6

Normal

composition – one

of the main

signature of

acceleration

at the forward

shock front of

SNR

Bump or dip or knee at the boundary of two

decreasing and increasing components: :

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1010

1011

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107

3

.0

FxE

E (GeV)

d e m o d e m o d e m o d e m o d e m o






Galactic CR- Extra Galactic CR

signature

Basic model of composition and Emax of Galactic sources at high energies:

sources are spread

continuously in space

and time Additionally we introduced:

1) a stochastic nature of sources , using Green function formalism

2) the condition that Emax for Core Collapsed SN is distributed from 1 0TeV to 3 PeV

3) Actual nearby sources from gamma catalogues

L. Sveshnikova, O. Strelnikova, V. Ptuskin. Astropart. Phys. 2013, 50-52, pp

33-46

V. Ptuskin, V. Zirakashvili, and Eun-Suk

Seo, Astrophysical J. T. 718 p. 31–36.

2010

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1010

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106

ATIC-2; Tibet QGSJet

Tunka-133; Kascade-Grande

Calculation

F(E

)*E

2.7

m-2 s

-1 s

r-1 G

eV

1.7

E (GeV)

CC_SNR

SN IIb

SN Ia

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108

1E-4

1E-3

0,01

0,1

1

E GeV

C=d=3, =4

dgam=2, om=6

Source spectrum :Numerical simulations of diffusive shock acceleration

in SNRs. From V.N.Zirakashvili, V.S.Ptuskin :

http://arxiv.org/pdf/1109.4482.pdf

Spectra of particles

produced in the

supernova remnant

during 100 000 yr.

injected at the forward

shock (thick solid line ), ,

spectrum of ions injected

at the reverse shock (thick

dashed line)

1)The first version of explanation of the inverse knee at 20 TeV was presented in ECRS 2012: Knee is provided mainly by CR accelerated in SN_Ia or other group of sources with similar Emax. We can directly obtain the chemical composition if we suggest the nearly same slopes for species. In this case hardening at 20 PeV is produced by increase of heavy nuclei.

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1010

1011

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Si

CNOHe

P

Z

Z14

Z

Z

Tunka133 Tunka25 Kascade Gr. Kascade

EASTOP Tibet Augergv Hires1M3 Hires2

Fe_Tunka Fe Kasc. Gr.

F(E

) E

3.0

E, GeV

Z1

All

It was shown: 1) Composition is enriched by Fe: P+He(~55-60) CNO(10%) Si-Ca(~10%),Fe (~20-25%) (Dark blue points) 2) Source spectrum has a sharp cutoff

2013:New data from Tunka-133: the ratio of Fe was decreased essentially, so the hardening after 20 PeV is

caused by the appearance of a new component

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109

106

107

F(E

) E

3.0

E, GeV

new Fe

P+HE

d e m o d e m o d e m o d e m o









After subtracting the contribution of CR provided the knee we have the rest that reminds most of all

well known “dip” model

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109

1010

1011

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106

107

F(E

) E

3.0

E, GeV










P+He

HIRES

rest

Extragalactic CR: “Dip model” (V. Berezinsky. (2013) arXiv:1301.0914 V. Berezinsky, et al Phys. Lett. B 612,147 (2005)+ “magnetic horizon effect” (M. Lemoine, Phys. Rev. D

71, 083007 (2005), R. Aloisio and V. Berezinsky, ApJ 625, 249 (2005)]

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1010

1011

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107

[12] g=-2.7 Emax=10^22ev

Calculations [15] , B=2 nG

Mod.2, lc=100, ns=10^-5

Mod. 3, lc=30, ns=10^-6

Mod. 4, lc=100, ns=10^-5

Mod. 1, lc=300, ns=10^-5

Approximations in Fig.1

1 2 3

3

.0

FxE

E (GeV)









Low energy behaviour depends on mean strength of magnetic field B0=0.3-3 nG,

coherence length lc ~ 30- 300 kpc, source density ns=10^-5-10^-6

the diffusion time

of particles with

energy E <

10^17 eV from

the closest

sources

(50−100Mpc)

becomes longer

than the age of

the Universe.

K. Kotera and M. Lemoine

arXiv:0706.1891v2

Signature of e+e- pair-

production in interaction of

UHE protons with CMB

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1010

1011

EASTOP [18] Tibet [17] KASCADE[19]

Tunka 25,133 [1] KASC. Gr. 2012 [3] Ice Top [5]

Model prediction

Sum of Gal. + Extragal.: 3 2 1 P+He

Extragal. : 3 2 1

Galactic : All P+He Z>6 Z>14 Z>20

F(E

) E

3.0

m

-2 s

-1 s

r-1G

eV

2

E, GeV

Galactic - Extragalactic

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109

1010

1011

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107

EASTOP [18] Tibet [17] KASCADE[19]

Tunka 25,133 [1] KASC. Gr. 2012 [3] Ice Top [5]

Model prediction

Sum of Gal. + Extragal.: 3 2 1 P+He

Extragal. : 3 2 1

Galactic : All P+He Z>6 Z>14 Z>20

F(E

) E

3.0

m-2 s

-1 s

r-1G

eV2

E, GeV









The all particle spectrum, light component and heavy component measured in Tunka-

133 can be described with the model when knee is produced by the special class

of sources with ~ same Emax and approximately normal chemical composition, the

extragalactic protons arises between 10^16 ÷ 10^17 eV thus stressing the hardening

of all particle spectrum at 20 PeV, the contribution of extragalactic protons reaches 50%

of all particles around 200-300 PeV.

CONCLUSION I

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1010

0

1

2

3

4

5 Kascade[24] MSU [25]

ATIC2[22] Tunka 25,133 [2] [1]

Jacee [23] Auger [26] Ice Top

Model prediction 3, 2, 1,

<

ln A

>

E (GeV)

Tunka 133 - <lnA> -black full stars (2012); open stars (2013)

75% P+25% He

Nuclear component

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109

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2x106

3x106

4x106

5x106

Heavy

Model prediction

Galactic : Z>6 Z>14 Z>20

F(E

) E

3.0

m

-2 s

-1 s

r-1

GeV

2

E, GeV

Red-new 11June

Fe

Z>6








These points, if they

are not of methodical

reasons, are beyond

the model. The

systematic errors are

very large.

Defects 1. This model gives the dip only at proton or light

composition of extragalactic CR !!! It assumes

rightness of Hires and TA data, Auger data are in

strong contradiction.

2. Dip and GZK cutoff can be modified by

discreteness in sources distribution, by source

local overdensity or deficit and by different value

of Emax (V. Berezinskii)

Transition region from the numerous SNRs to the SNRs or other sources providing the knee is

a very interesting region

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Calculation

F(E

)*E

2.7

m-2 s

-1 s

r-1 G

eV

1.7

E (GeV)

CC_SNR

SN IIb

SN Ia

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109

1010

105

106

107

Tunka P

Atic2, A

rgo P+He

IxE

3.0 m

-2 s

-1 s

r-1

GeV

2.0

En, GeV

Atic2 a

ll

Tunka All

Tunka P+He







P +He: Atic2, Argo, - Tunka – the same slope as in all particle spectrum

All Nuclei, Fe nuclei : Atic2->Tunka 133

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1010

104

105

106

107

IxE

3.0 m

-2 s

-1 sr-

1 G

eV

2.0

E0, GeV

allNuc

Atic

N>CNO

N>Fe

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109

1010

105

106

107

Ix

E3.0 m

-2 s

-1 s

r-1 G

eV

2.0

En, GeV










CNO: from Atic 2 to Tunka-133

Atic2

Atic2

Conclusion II

1. Group of sources providing the knee look like

SNRs, because source spectrum and composition

are in agreement with the standard model of

acceleration by SNR forward shock.

2. But in the region 100-4000 PeV – transition region

from usual SNRs to rare sources providing the

knee, we believe some new features in spectrum

and composition will be found.

3. In 2014-2015 the first 20 stations of Hiscore –

Tunka non imaging Cherenkov array starts to

measure HE gammas and background cosmic rays

Nearby sources

Cas A – a very good candidate

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101010

5

106

107

3

.0

FxE

E (GeV)

CAS A (SNR of IIb type - nearest )

Source spectrum -2.02

Emax=210^17 eV

twice power for CR prod.

Light composition

Fe~2%









Many unusual properties from (J.

Vink. arXiv:1112.0576v2 ) J

1. Cas A must have been a Type IIb

SNR, similar to SN1993J

2. Progenitor main sequence mass of

18±2M⊙.

3. Strong bipolarity referred to as “the

jet”.

4. Best explained with a binary star

scenario, in which a high mass loss is

caused by a common envelope phase.

L.G. Sveshnikova, E.E. Korosteleva, L.A. Kuzmichev, et al, Journal of

408 Physics: Conference Series, 409, 1 (2013)012062; arXiv:1303.1713.

Tunka2013

Tunka 2011

•

• 1) Sources spectrum: ~ 1.7-2.01, • Emax ~ z(23)1017 , • very light composition P+He~95%, Fe<2%

• 2) Closest sources should be at distance ~2-4

kpc, T < 100 ky

• 3) One source with usual power is enough, may be Cas A??? SNRIIb type

Contribution of nearby sources around the knee

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Vela Jr (0.3 kpc 0.7 ky)



Calculation

F(E

)*E

2.7

m-2 s

-1 s

r-1 G

eV

1.7

E (GeV)

HB9

Cygnus Loop

HB21

Vela Jr. (0.7 kpc 1.7 ky)







We could not exclude the “single source”

But only Vela Jr. can provide the structure around the knee and

only if : 1) Emax=F(Temission) 2) D~0.3 kpc, T~0.7 ky

It’s very difficult to

obtained high Fe content

around 10^17 eV.

Bachground sources also

have high Fe content

Thank you !

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Atic2, A

rgo P

+He

IxE

3.0 m

-2 s

-1 s

r-1

Ge

V2

.0

En, GeV

HeJac 2.63

Atic2 a

ll

Tunka All

Tunka P+He

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1010

104

105

106

107

IxE

3.0 m

-2 s

-1 sr-

1 G

eV2.

0

En, GeV

allNuc

Atic

N>CNO

N>Fe

Fe Kascade

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1010

105

106

107

IxE

3.0 m

-2 s

-1 s

r-1 G

eV

2.0

En, GeV

CNO

Mass composition

interpretation of cosmic ray spectrum above the knee measured...

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