Cosmic Ray Transport

1
Cosmic Ray Transport in the Galaxy Vladimir
Ptuskin IZMIRAN, Russia
2
Ncr 10-10 cm-3 - total number density wcr
1.5 eV/cm3 - energy density Emax 3x1020 eV -
max. observed energy dcr 10-3 at 1012 - 1014
eV - anisotropy rg 1E/(Z31015 eV) pc -
Larmor radius

ulsar
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source spectrum
E-2.7 cosmic ray density
Ncr T
source spectrum E-(2.0 2.4)
Qcr
escape time E-(0.3 0.6)
two power laws source spectrum propagation
secondary species Qcr,2 nvs21N1 d, 3He, Li,
Be, B p, e
escape length X ?vT
10 g/cm2 at 1 GeV/nucleon
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basic empirical diffusion model
Ginzburg Ptuskin 1976, Berezinskii et al. 1990,
Strong Moskalenko 1998 (GALPROP code)
surface gas density 2.4 mg/cm2
cosmic-ray halo
Sun
escape length
SNR
2H
galactic disk
r 20 kpc
- plain diffusion break of D at 5 GV
- diffusion reacceleration
Va 30 km/s
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some explanations of peak in sec./prim. ratio
Xe
v

• convective transport
• Jones 1979

problem too broad sec/prim peak
R-0.6
wind or turbulent diffusion
resonant diffusion
E

• distributed reacceleration
• Simon et al. 1986 Seo Ptuskin 1994
• Dpp p2Va2/D, D vR1/3
• - Kolmogorov spectrum of turbulence

Icr
?E
problem low flux of secondary antiprotons
weak reacceleration
strong reaccele- ration
E

• wave damping on cosmic rays

nonlinear cascade
W(k)
VSP, Moskalenko et al. 2004
damping
problem cascade availability
W(k) k-3/2 D vR1/2
Iroshnikov - Kraichnan cascade D0 vR1/2
k
1/1020cm
1/1012cm
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Sina et al. 2001
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radioactive secondaries
10Be (2.3 Myr) 26Al (1.3 Myr) 36Cl (0.43
Myr) 54Mn (0.9 Myr) 14C (0.0082 Myr)
decay time at rest
d
gas density
primaries
D (2 5)1028 cm2/s at
0.5 GeV/n
H 4 kpc, Tesc 70 Myr
Ptuskin Soutoul 1998
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flat component of secondary nuclei produced by
strong SNR shocks Wandel et al. 1987, Berezhko
et al. 2003
production by primaries inside SNRs
reacceleration in ISM by strong shocks
grammage gained in SNR
volume filling factor of SNRs
grammage gained in interstellar gas
Berezhko et al. 2003
RUNJOB 2003 preliminary
plain diff. reacceleration nism 0.0031
cm-3 Bohm diffusion TSNR 105 yr
standard plain diff. reacceleration
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microscopic theory of cosmic-ray diffusion
resonant interaction rg 1 / k
p
Larmor radius
resonant wave number
parallel diffusion Jokipii 1966 anomalous perpend
icular diffusion Jokipii Parker 1970 Chuvilgin
Ptuskin 1993 Giacolone Jokipii 1999 Casse et
al 2001 Hall diffusion
lt B gt dB
109 eV
1017 eV
Armstrong et al 1995
W(k) k-5/3 k-3/2
hot topic anisotropic Alfvenic turbulence
Shebalin et al. 1983, Higdon 1984, Bieber
et al. 1994, Montgomery Matthaeus
1995, Goldrreich Shridhar 1995, Lazarian et al.
2003
Kolmogorov
Kraichnan
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galactic wind driven by cosmic rays

Ipavich 1975, Breitschwerdt et al.
1991, 1993 cosmic ray streaming instability with
nonlinear saturation
CR emissivity of Galactic disk per unit area
Zirakashvili et al. 1996, 2002 Ptuskin et al. 1997
uinf 500km/s Rsh 300 kpc
stable secondaries
radioactive secondaries
effective halo size H(p/Z)
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empirical spectrum of galactic cosmic ray
sources problem for theory of diffusive shock
acceleration
high energy asymptotic
R-2.15
low energies, R lt 30 GV
plane diffusion D ßR0.54
R-2.35 Davis et al. 2000 R-2.50 Moskalenko
et al. 2004
Q
concave spectrum
E
diffusion with reacceleration D ßR0.3
R-2.40(1(2/RGV)2)-1/2 Jones et al. 2001
Q
flattened at low energy
E
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spectrum of very high energy electrons Shen
1970, Cowsik Lee 1979, Nishimura et al. 1979,
1997, Dorman et al. 1985,Aharonian et al. 1995,
Kobayashi et al. 2004
plain diffusion
Vela
S147
Cygnus
SN185
HB21
G65.3
Monogem
G347.3
Golden et al. 1984 Tang et al. 1984 Barwick et
al.1998 Kobayashi et al. 1999 Boezio et al.
2000 Tori et al. 2001
reacceleration
Vela
tloss 2.3105yr(ETeV)-1
Cygnus
Emax 100 TeV
Monogem
G65.3
HB21
TeV
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l 1 Z kpc
data
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knee as effect of propagation
Candia et al 2003
Galactic disk
ltBgt
Hall diffusion in average Galactic magnetic
field Ptuskin et al.1993 Kalmykov Pavlov
1999 Candia et al. 2003
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alternative at ultra-high energies
JE3
TUNKA collaboration 2005
extragalactic p
Fe
p
two components Galactic (heavy) extragalactic
(protons ?) Bird et al. 1993
E, eV
limit for acceleration In Galactic sources
knee
1015
1017
1019
JE3
Fe
pure Galactic origin Pochepkin et al. 1998
p
problems with acceleration and anisotropy
switch to free exit from the Galaxy
knee
E, eV
1015
1017
1019
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Tdisk kyr
trajectory calculations
Zirakashvily et al. 1998
simple magnetic field structure
average field random field
B0 1 µG, a 1.5 kpc, r1 0.5 kpc Br/B0 3,
L 100 pc, R 20 kpc
p
p
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3x1019 eV
pure Galactic
mixed
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extra- galactic?
galactic
trajectory claculations
diffusion approximation (protons)
knee
2nd knee
dispersion of SNs? reacceleration? early
transition to extragalactic CRs?
Nagano Watson 2000
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Conclusion
Diffusion model provides reasonably good
description of cosmic ray propagation in the
Galaxy even under simplified assumptions on
cosmic ray transport coefficients and geometry of
propagation region. The choice between plain
diffusion model and the model with reacceleration
is difficult to make Plain diffusion model
predicts too large anisotropy at E gt 100 TeV.
Diffusion model with reacceleration is bearably
compatible with data on cosmic ray anisotropy.
Source spectrum in the plain diffusion model is
close to prediction of diffusive shock
acceleration theory. Source spectrum in the model
with reacceleration is considerably steeper.