GALPROP: principles, internal structure, recent results, and perspective

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GALPROP principles, internal structure, recent
results, and perspective
Igor V. Moskalenko Andy W. Strong NASA/GSFC
MPE, Germany with Olaf
Reimer Bochum, Germany
Topics to cover

• GALPROP principles, inputs/outputs, calculations
• Recent results (GeV excess pbars, extragalactic
  background)
• Dark Matter
• Near future developments

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Transport Equation
sources (SNR, nuclear reactions)
diffusion
convection
diffusive reacceleration
convection
E-loss
radioactive decay
fragmentation

• ?(r,p,t) density per total momentum

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CR Propagation Milky Way Galaxy
1 kpc3x1018 cm
Optical image Cheng et al. 1992, Brinkman et al.
1993 Radio contours Condon et al. 1998 AJ 115,
1693
100 pc
NGC891
40 kpc
0.1-0.01/ccm
1-100/ccm
Sun
4-12 kpc
Intergalactic space
R Band image of NGC891 1.4 GHz continuum (NVSS),
1,2,64 mJy/ beam
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CR Interactions in the Interstellar Medium
ISM
X,?
synchrotron
Chandra
IC
P He CNO
diffusion energy losses reacceleration
convection etc.
bremss
p
0
GLAST
p
LiBeB
p
Halo
He CNO
disk
solar modulation
ACE
escape
AMS
BESS
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GALPROP Input galdef-files

• GALPROP is parameter-driven (user can specify
  everything!)
• Grids
• 2D/3D options symmetry options (full 3D, 1/8
  -quadrants)
• Spatial, energy/momentum, latitude longitude
  grids
• Ranges energy, R, x, y, z, latitude longitude
• Time steps
• Propagation parameters
• Dxx, VA, VC injection spectra (p,e)
• X-factors (including R-dependence)
• Sources
• Parameterized distributions
• Known SNRs
• Random SNRs (with given/random spectra), time
  dependent eq.
• Other
• Source isotopic abundances, secondary particles
  (pbar , e, ?, synchro), anisotropic IC, energy
  losses, nuclear production cross sections

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Grids

• Typical grid steps (can be arbitrary!)
• ?z 0.1 kpc, ??z 0.01 kpc (gas averaging)
• ?R 1 kpc
• ?E x1.2 (log-grid)

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Gas Distribution
Molecular hydrogen H2 is traced using J1-0
transition of 12CO, concentrated mostly in the
plane (z70 pc, Rlt10 kpc) Atomic
hydrogen H I has a wider distribution
(z1 kpc, R30 kpc) Ionized hydrogen H II
small proportion, but exists even in halo (z1
kpc)
Sun
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Interstellar Radiation Field
Energy density

• Stellar
• Dust
• CMB

Sun
Energy density
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Nuclear Reaction NetworkCross Sections
Secondary, radioactive 1 Myr K-capture isotopes
Co57
Fe55
Mn54
Cr51
V49
Ca41
Ar37
Cl36
ß-, n
Al26
p,EC,ß
Be7 Be10
Plus some dozens of more complicated
reactions. But many cross sections are not well
known
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Nuclear component in CR What we can learn?
Nucleo- synthesis supernovae, early universe,
Big Bang
Stable secondaries Li, Be, B, Sc, Ti, V
Propagation parameters Diffusion coeff., halo
size, Alfvén speed, convection velosity
Radio (t1/21 Myr) 10Be, 26Al, 36Cl, 54Mn
K-capture 37Ar,49V, 51Cr, 55Fe, 57Co
Energy markers Reacceleration, solar modulation
Diffuse ?-rays Galactic, extragalactic
blazars, relic neutralino
Short t1/2 radio 14C heavy Zgt30
Local medium Local Bubble
Solar modulation
Heavy Zgt30 Cu, Zn, Ga, Ge, Rb
Material acceleration sites, nucleosynthesis
(r-vs. s-processes)
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Fixing Propagation Parameters Standard Way

• Using secondary/primary nuclei ratio
• Diffusion coefficient and its index
• Propagation mode and its parameters (e.g.,
  reacceleration VA, convection Vz)

B/C
Interstellar
Be10/Be9
Ek, MeV/nucleon
Radioactive isotopes Galactic halo size Zh
Zh increase
Ek, MeV/nucleon
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Peak in the Secondary/Primary Ratio

• Leaky-box model
• fitting path-length distribution -gt free
  function

• Diffusion models
• Diffusive reacceleration
• Convection
• Damping of interstellar turbulence
• Etc.

B/C
Measuring many isotopes in CR simultaneously may
help to distinguish
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Heliosphere
Flux
20 GeV/n
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Electron Fluctuations/SNR stochastic events
GeV electrons
100 TeV electrons
GALPROP/Credit S.Swordy
Energy losses
Bremsstrahlung
E(dE/dt)-1,yr
Ionization
IC, synchrotron
Electron energy loss timescale 1 TeV 300 000
yr 100 TeV 3 000 yr
Coulomb
107 yr
1 TeV
1 GeV
106 yr
Ekin, GeV
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CR Variations in Space Time

• More frequent SN
• in the spiral arms

Historical variations of CR intensity over 150
000 yr (Be10 in South Polar ice)
Konstantinov et al. 1990
Electron/positron energy losses
Different collecting areas A vs. p
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GALPROP Output/FITS files

• Provides literally everything
• All nuclei and particle spectra in every grid
  point (x,y,R,z,E) -FITS files
• Separately for p0-decay, IC, bremsstrahlung
• Emissivities in every grid point
  (x,y,R,z,E,process)
• Skymaps with a given resolution (l,b,E,process)
• CONSUMERS
• AMS, Pamela dark matter searches
• ACE, TIGER interpretation of isotopic
  abundances
• HEAT electrons, positrons
• GLAST(?) spectrum of the diffuse emission
  background model

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algorithm
numerical solution of cosmic-ray transport 2D or
3D grid time-independent or time-dependent
primary source functions (p, He, C ....
Ni) source abundances, spectra primary
propagation -starting from maxA64
source functions (Be, B...., e,e-, pbars) using
primaries and gas distributions secondary
propagation
tertiary source functions tertiary propagation
?-rays (IC, bremsstrahlung, po-decay) radio
synchrotron
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GALPROP Calculations

• Constraints
• Bin size (x,y,z) depends on the computer speed,
  RAM final run can be done on a very fine grid !
• No other constraints ! any required
  process/formalism can be implemented
  vectorization !!
• Calculations (? -ray related)
• Vectorization options
• Heliospheric modulation routinely force-field,
  can use Potgieter model
• For a given propagation parameters propagate p,
  e, nuclei, secondaries (currently in 2D)
• The propagated distributions are stored
• With propagated spectra calculate the
  emissivities (p0-decay, IC, bremss) in every grid
  point
• Integrate the emissivities over the line of
  sight
• GALPROP has a full 3D grid, but currently only 2D
  gas maps (H2, H I, H II)
• Using actual annular maps (column density) at the
  final step
• High latitudes above b40 -using integrated H I
  distribution

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Near Future Developments

• Full 3D Galactic structure
• 3D gas maps (from S.Digel, S.Hunter and/or smbd
  else)
• 3D interstellar radiation magnetic fields
  (A.Strong T.Porter)
• Cross sections
• Blattnig et al. formalism for p0-production
• Diffractive dissociation with scaling violation
  (T.Kamae)
• Isotopic cross sections (with S.Mashnik, LANL
  try to motivate BNL, JENDL-Japan, other Nuc. Data
  Centers)
• Energy range
• Extend toward sub-MeV range to compare with
  INTEGRAL diffuse emission (continuum 511 keV
  line)
• Modeling the local structure
• Local SNRs with known positions and ages
• Local Bubble may be done at the final
  calculation step
• Heliospheric modulation
• Implementing a complimentary drift model by
  M.Potgieter
• Visualization tool (started) using the classes of
  CERN ROOT package images, profiles, and spectra
  from GALPROP to be directly compared with data
• Improving the GALPROP module structure (for DM
  studies) developing a dedicated Web-site to
  allow for a communication with users

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• Recent results

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Wherever you look, the GeV ? - ray excess is
there !
4a-f
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Reacceleration Model Secondary Pbars
B/C ratio
Antiproton flux
Ek, GeV
Ek, GeV/nucleon
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Positron Excess ?
HEAT (Coutu et al. 1999)

• Are all the excesses connected somehow ?
• A signature of a new physics (DM) ?
• Caveats
• Systematic errors ?
• A local source of primary positrons ?
• Large E-losses -gt local spectrum

e/e
GALPROP
Leaky-Box
1
10
100
E, GeV
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Matter, Dark Matter, Dark Energy

• O ?/?crit
• Otot 1.02 /-0.02
• OMatter 4.4 /-0.4
• ODM 23 /-4
• OVacuum 73 /-4

SUSY DM candidate has also other reasons to exist
-particle physics
Supersymmetry is a mathematically beautiful
theory, and would give rise to a very predictive
scenario, if it is not broken in an unknown way
which unfortunately introduces a large number of
unknown parameters Lars Bergström (2000)
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Example Global Fit diffuse ?s, pbars,
positrons
GALPROP/W. de Boer et al. hep-ph/0309029

• Supersymmetry
• MSSM
• Lightest neutralino ?0
• m? 100-500 GeV
• S½ Majorana particles
• ?0?0-gt p, pbar, e, e-, ?

?
pbars

• Look at the combined (pbar,e,?) data
• Possibility of a successful global fit can not
  be excluded -non-trivial !
• If successful, it may provide a strong evidence
  for the SUSY DM

e
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GeV excess Optimized model

• Uses all sky and antiprotons gammas
• to fix the nucleon and electron spectra
• Uses antiprotons to fix
• the intensity of CR nucleons _at_ HE
• Uses gammas to adjust
• the nucleon spectrum at LE
• the intensity of the CR electrons
• (uses also synchrotron index)
• Uses EGRET data up to 100 GeV

antiprotons
protons
electrons
x4
x1.8
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Diffuse Gammas from Secondary Positrons/Electrons
Interstellar
Heliosphere
electrons
e0.1e-
e/e
sec.e-10
positrons
ee-
Important below 200 MeV
gammas
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Anisotropic Inverse Compton Scattering

• Electrons in the halo see anisotropic radiation
• Observer sees mostly head-on collisions

Energy density
e-
R4 kpc
small boost less collisions
e-
head-on large boost more collisions
Z, kpc
?
?
?
Important _at_ high latitudes !
sun
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Diffuse Gammas at Different Sky Regions
Hunter et al. region l300-60,blt10
Outer Galaxy l90-270,blt10
Intermediate latitudes l0-360,10ltblt20
Intermediate latitudes l0-360,20ltblt60
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Longitude Profiles blt5
50-70 MeV
0.5-1 GeV
2-4 GeV
4-10 GeV
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Latitude Profiles Inner Galaxy
50-70 MeV
2-4 GeV
0.5-1 GeV
4-10 GeV
20-50 GeV
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Latitude Profiles Outer Galaxy
50-70 MeV
0.5-1 GeV
2-4 GeV
4-10 GeV
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Extragalactic Gamma-Ray Background
Predicted vs. observed
E2xF
Sreekumar et al. 1998
Elsaesser Mannheim, astro-ph/0405235
Strong et al. 2004
E, MeV

• Blazars
• Cosmological neutralinos

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Distribution of CR Sources Gradient in the CO/H2
CR distribution from diffuse gammas (Strong
Mattox 1996) SNR distribution (Case
Bhattacharya 1998) Pulsar distribution
(Lorimer 2004)
sun
XCON(H2)/WCO Histo This work, Strong et
al.04 ----- -Sodroski et al.95,97 1.9x1020
-Strong Mattox96 Z-1 Boselli et
al.02 Z-2.5 -Israel97,00, O/H0.04,0.07
dex/kpc
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Again Diffuse Galactic Gamma Rays
Very good agreement !
More IC in the GC better agreement !
The pulsar distribution vs. R falls too fast OR
larger H2/CO gradient
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Conclusions I

• Accurate measurements of diffuse gamma rays,
  secondary antiprotons, and other CR species
  simultaneously may provide a new vital
  information for Astrophysics in broad sense,
  Particle Physics, and Cosmology.

Hunter et al. region l300-60,blt10
Gamma rays GLAST is scheduled to launch in 2007
diffuse gamma rays is one of its priority goals
Dark Matter
CR species New measurements at LE HE
simultaneously are highly desirable (Pamela,
S-TIGER, AMS), sec. positrons !
B/C
Be10/Be9
Zh increase
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Conclusions II

• Antiprotons Pamela (2005), AMS (2008) and a new
  BESS-polar instrument to fly a long-duration
  balloon mission (in 2004, 2006), we thus will
  have more accurate and restrictive antiproton
  data

HE electrons Several missions are planned to
target specifically HE electrons
We must be ready! GALPROP is a propagation model
to play now
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• Thank you !