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Igor V. Moskalenko/NASA-GSFC 1 Nuclear Data-2004/09/28, Santa Fe
Cosmic rays in the local interstellar medium
Igor V. MoskalenkoStanford
LMC (Magellanic Cloud Emission Line Survey: Smith, Points)
R - HG - [S II]
B - [O III]
Igor V. Moskalenko 2 GALPROP Workshop, Dec. 5-6, 2011 Stanford
R - HG - [S II]
B - [O III]500 pc
Supergiant shells
~ 1000 pc
~ 107 yr
(multi generations)
Superbubbles ~ 100 pc ~ 106 yr (OB associations)
Bubbles, SNRs ~ 10 - 50 pc ~ 103 – 105 yr (single star)
MCELS: Smith, Points
Igor V. Moskalenko 3 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Red: H Green: [O III]
Blue: X-ray
LMC Superbubble: N11
LMC Superbubble: N57 LMC Superbubble: N70
Igor V. Moskalenko 4 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Motivation
• SNRs are the conventional sources of the majority of CRs
• Multiple SN explosions within a single OB association may have a profound effect on CR spectra and CR distribution in a galaxy
• May leave signatures in isotopic source abundances (e.g. 22Ne)
• The evolution of a SNR shell in a superbubble (rarefied ionized gas) may be quite different from that of a SNR in the typical cold ISM (e.g. may accelerate to higher energies)
Igor V. Moskalenko 5 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Why is the local interstellar medium?
• Can be probed fairly well assuming the spectra of CR species do not change much within ~100 pc (see yesterday’s talk by Seth Digel)
• May have measurable signatures due to the proximity of the sources and propagation effects (e.g. PAMELA positron fraction, breaks in p & He spectra at 230 GV)
• May produce visible effects on the gamma-ray skymaps (e.g features and residuals)
Igor V. Moskalenko 6 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Fermi-LAT residual skymaps (submitted to ApJ)
Model 44: LorimerZ6R20T∞C5 (see Gulli’s talk)
PRELIMINARY
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Local Bubble
X-Y plane
X-Z plane
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The origin of the Local Bubble
• The LB - low-density region around the Sun, filled with hot/warm H I gas• The size of the region is about 200 pc • It is likely that the LB was produced in a series of SN explosions• Most probably its progenitor was OB star associations• The age ~10 Myr, the last SN explosion was ~1–2 Myr ago, or three SNs
during the last 5 Myr• A detailed study (Abt 2011) shows three different regions with different
ages:– The region towards the Galactic center ~4 Myr (with a pulsar ~4 Myr old)– The central lobe <160 Myr– Pleiades lobe ~50 Myr
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450 pc in the solar neighborhood
High density molecular clouds around starforming regions
OB associations
Hot ionized gas
Credit: Frisch
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The location of interstellar clouds in the Galactic Plane
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Four closest warm clouds
Shapes of the four closest to the heliosphere interstellar clouds (edges within 1-5 pc) in Galactic coordinates Linsky&Redfield’2009
Igor V. Moskalenko 12 GALPROP Workshop, Dec. 5-6, 2011 Stanford
The morphologies of 15 clouds (within 15 pc)
Frisch+’2011
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Mean extinction for stars within 500 pc
Frisch’2007
Magenta contours – interaction of Loop I with the LB
Rings – OB associations
Black contours –
the integrated stellar radiation at 1565 Å (TD-1 satellite)
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44: LorimerZ6R20T∞C5
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Effects on Cosmic Rays
Igor V. Moskalenko 16 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Propagation of CRs
• Effect of the local underdensity on “radioactive clock” isotopes 10Be, 26Al, 36Cl (Donato+’2002)
– Reduces the abundance of radioactive isotopes at the position of the Sun
– 36Cl/Cl is the most sensitive (shortest half-life)
– Affects propagation parameters
• However, the diffusion coefficient in the LB is unknown
Igor V. Moskalenko 17 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Propagation of CRs
• Effect on propagation parameters due to the local component of CRs at low energies (Moskalenko+’2003). Only primary local elements were considered
– Increased abundances of primary elements (C, O, Fe…) at LE
– Secondary elements are produced by Galactic CRs and are not produced by the local CRs
– Affects propagation parameters: more secondaries to be produced Galaxy-wide (e.g., larger B/C)
Galactic
Local
Igor V. Moskalenko 18 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Total inelastic nuclear cross sections
Ekin, MeV/nucleon
² The inelastic cross section gives a probability of interaction
² Rises with the atomic number as ~A2/3
² As the result of interaction the original nucleus is destroyed
Wellisch & Axen 1996
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Effective propagation distance: LE nuclei
² The interaction time scale at ~1 GeV – 1 TeV:
τ ~ L/c ~ [σnc]-1 ~ 3×1013/[0.25 (A/12)2/3] s ~ 3×106 yr (A/12)−2/3
σCarbon(A=12) ≈ 250 mb;n ~ 1 cm−3 (in the plane)
² The diffusion coefficient (4 kpc halo):
D ~ 3×1028 R1/2 cm2/s, R – rigidity in GV
² Effective propagation distance (in the plane):
<X> ~ √6Dτ ~ 4.5×1021 R1/4 (A/12)−1/3 cm ~ 1.5 kpc R1/4 (A/12) −1/3
Helium: ~ 2.1 kpc R1/4
Carbon: ~ 1.5 kpc R1/4 0.36% of the surface area (25 kpc radius)
Iron: ~ 0.9 kpc R1/4 0.16%
(anti-) protons:~ 6 kpc R1/4 5.76%
² γ-rays: probe CR p (pbar) and e± spectra in the whole Galaxy ~50 kpc across
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Direct probes of CR propagation
² Direct measurements probe a very small volume of the Galaxy
² The propagation distances are shown for rigidity ~1 GV
50 kpc
pC
Fe
Igor V. Moskalenko 21 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Energy losses of electrons
² The ionization and Coulomb losses are calculated for the gas number density 0.01 cm-3
² Energy density of the radiation and magnetic fields 1 eV cm-3 (Thomson regime)
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Effective propagation distance: HE electrons
² The energy loss time scale (IC) at ~1 GeV – 1 TeV:
τ~ 300 E12−1 kyr ~ 1013 E12−1 s; E12 – energy in TeV
² The diffusion coefficient:
D ~ (0.5-1)×1030 E121/2 cm2/s
² Effective propagation distance:
<X> ~ √6Dτ ~ 5×1021 E12−1/4 cm ~ 1 kpc E12−1/4
~ a few kpc at 10 GeV
² The cutoff energy of the electron spectrum ~1 TeV can be used to estimate the distance to the local HE electron sources: ≥ a few 100 pc.
Igor V. Moskalenko 23 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Direct probes of CR propagation
² Direct measurements probe a very small volume of the Galaxy
² The propagation distances are shown for nuclei for rigidity ~1 GV, and for electrons ~1 TeV
50 kpc
p, 10 GeV eC
Fe, TeV e
Igor V. Moskalenko 24 GALPROP Workshop, Dec. 5-6, 2011 StanfordWR-124 in Sagittarius—Hubble Image
The origin of cosmic rays
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Detailed comparison
Good
Xsections
Well-known
15N33S
55Mn
41Ca*
53Mn*40Ca
22Ne
20Ne
32S
F
P
ScTiV
IM+’2007
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Igor V. Moskalenko 27 GALPROP Workshop, Dec. 5-6, 2011 Stanford
A-dependence of the source abundance ratio
Meyer+’1997
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0.25
0.3
0.4
0.5
0.60.70.80.9
1
2
3
4
5
66
76G
e/74
Ge
72G
e/74
Ge
70G
e/74
Ge
71G
a/69
Ga
68Z
n/64
Zn
66Z
n/64
Zn
65C
u/63
Cu
WR Model CRIS data (Binns et al. 2005)Combined data corr for volatility New CRIS UH-Isotopes
Rat
io R
elat
ive
to S
ola
r S
yste
m A
bun
danc
es
64N
i/58N
i
62N
i/58N
i
61N
i/58N
i
60N
i/58N
i
58F
e/56
Fe
12C
/16O
13C
/12C
14N
/16O
22N
e/20
Ne
23N
a/24
Mg
25M
g/24
Mg
26M
g/24
Mg
29S
i/28S
i30
Si/28
Si
34S
/32S
54F
e/56
Fe
57F
e/56
Fe
N/N
e
Model source abundance:
80% solar + 20% Wolf-Rayet
Relative isotopic source abundance
Binns+’2011
• Why Wolf-Rayet material is so important?
Igor V. Moskalenko 29 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Schematic OB association timeline
Binns+’2008
Igor V. Moskalenko 30 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Elemental Abundances relative to 80/20 mix of SS and massive
star outflow (MSO)
10 20 30 40 50 60 70 80 90100
0.1
1
GC
RS
/Lod
ders
-SS
Atomic Mass
Mg
Al
Si
P
CaFe
Co
Ni
Sr
N
Ne S
Ar
Cu
Zn
Ga
Ge
Se
Refractories
Volatiles
TIGER-LDB/Meetings/COSPAR-2010/100-0 mix_TIGER_Bobs_fits
TIGER+HEAO-C2 data
TIGER+HEAO-3 data
Elemental Abundances relative to SS only
Rauch+’2009
Igor V. Moskalenko 31 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Same dependence at TeV energies
ACE/CRIS CREAM
Rauch+’2009 Ahn+’2010
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Backup slides
Igor V. Moskalenko 33 GALPROP Workshop, Dec. 5-6, 2011 Stanford
THANKS TO EVERYBODY AND ESPECIALLY TO GUESTSWHO MADE IT TO STANFORD !
Igor V. Moskalenko 34 GALPROP Workshop, Dec. 5-6, 2011 Stanford
First Ionization Potential (FIP) vs. Volatility
• Low-FIP ~ Refractories• Rb, Cs – break the rule• Other important elements: Na,
Cu, Zn, Ga, Ge, Pb
Rb
CsK
Pb
GeGa
Na
Zn
Se
Cu
~104 K
Meyer, Drury, Ellison’1997
Igor V. Moskalenko 35 GALPROP Workshop, Dec. 5-6, 2011 Stanford
Rauch+’2009
36
Measured isotopic abundance ratios compared to Solar System Abundances (Lodders, 2003)
36
0.0
0.2
0.4
0.6
0.8
1.0
1.2
70/64
Ratio SS(Lodders)
Rat
io
65/63
Cu Zn Ga Ge
66/64 68/64 71/69 70/74 72/74 76/74
7_29_11_ICRC-Isotope_corrections/Isotope_ratio_figure.opj
• Abundances corrected for
– nuclear interactions in instrument
– Energy intervals• Abundances include
first order leaky box propagation back to the source
37
Comparison with 80%/20% mix of Solar System and WR material
37
• For these isotope ratios, the 80/20 mix is very similar to pure SS, within the accuracy of our measurement
• Measured ratios are consistent with either pure Solar System or an 80/20 mix of SS and massive star ejecta
0.0
0.2
0.4
0.6
0.8
1.0
1.2
70/64
Ratio SS(Lodders) 80%/20% SS/WR mix
Rat
io
65/63
Cu Zn Ga Ge
66/64 68/64 71/69 70/74 72/74 76/74
7_29_11_ICRC-Isotope_corrections/Isotope_ratio_figure.opj
38
30 32 34 36 38 40
1E-6
1E-5
1E-4
1E-3
ACE HEAO-C2 TIGERSolar System (LPK 2009)
Rel
ativ
e A
bund
ance
(F
e=1)
Charge (Z)
Abundances at thetop of the atmosphere
8_2_11-Element ICRC paper/Abund_rel_Fe_ACE_TIG_HEAO
Elemental Abundances Relative to Fe
Correction factors for saturated pulse heights at high-Z:
Z Corr
34 1.03
36 1.2
38 1.57
40 2.39
39
In Context of Previous Data at Lower Charge
39
0.25
0.3
0.4
0.5
0.60.70.80.9
1
2
3
4
5
66
76 G
e/7
4 Ge
72 G
e/7
4 Ge
70 G
e/7
4 Ge
71 G
a/6
9 Ga
68 Z
n/6
4 Zn
66 Z
n/6
4 Zn
65 C
u/6
3 Cu
WR Model CRIS data (Binns et al. 2005)Combined data corr for volatility New CRIS UH-Isotopes
R
atio
Rel
ativ
e to
Sol
ar S
yste
m A
bun
danc
es
64 N
i/58 N
i
62 N
i/58 N
i
61 N
i/58 N
i
60 N
i/58 N
i
58 F
e/5
6 Fe
12 C
/16 O
13 C
/12 C
14 N
/16 O
22 N
e/2
0 Ne
23 N
a/2
4 Mg
25 M
g/2
4 Mg
26 M
g/2
4 Mg
29 S
i/28 S
i3
0 Si/2
8 Si
34 S
/32 S
54 F
e/5
6 Fe
57 F
e/5
6 Fe
N/N
e
Binns+’2011
40
10 20 30 40 50 60 70 80 90100
0.1
1
TIGER Vol (gas) TIGER Ref (grains) HEAO-C2 VolHEAO C2 Ref HEAO C2-Mixed Vol & Ref ACE-Volatiles ACE-Refractories
GC
R S
ourc
e/(8
0% S
S +
20%
MS
O) (
Fe=1
)
Atomic Mass (A)8_2_11-Element ICRC paper/Spirce_GCRs_vs_Mass_80-20.opj
TIGER
ACE
Refractory
VolatileN
O
Ne
MgAl
Si
P
S
Ar
Ca Fe
Ni
Sr
Cu
Zn
Ga
Ge
Se
Elemental Abundances relative to 80/20 mix of SS and MSO
10 20 30 40 50 60 70 80 90100
0.1
1
GC
RS
/Lod
ders
-SS
Atomic Mass
Mg
Al
Si
P
CaFe
Co
Ni
Sr
N
Ne S
Ar
Cu
Zn
Ga
Ge
Se
Refractories
Volatiles
TIGER-LDB/Meetings/COSPAR-2010/100-0 mix_TIGER_Bobs_fits
TIGER+HEAO-C2 data
TIGER+HEAO-3 data
Elemental Abundances relative to SS only