What

1
Whats new and what questions remain since our
previous meeting?

• Workshop on
• Physics at the End of the Galactic Cosmic-ray
  Spectrum
• April 26-30, 2005

2
Outline

• Below the knee
• Knee region
• Sources acceleration mechanisms
• End of galactic cosmic-ray population?
• Where is transition to extra-galactic?
• What is the nature of the ankle?
• Extra-galactic cosmic rays and GZK
• Lessons from the heliosphere (2nd edition)

3
Final Results of RUNJOB and Related TopicsMakoto
Hareyama, Toru Shibata and the Runjob
collaboration
(Aspen, 2005)
Observed spectrum E(-2.7) to 100 TeV
JACEE and results of other balloon experiments
100 TeV reported by M. Cherry, Aspen 2005
4
All particle spectrum
Note difference between JACEE and RUNJOB for
100 TeV helium
5
ATIC, John Wefel, Tokyo 07 (also discussed in
Cherrys talk, Aspen 2005)
Helium more like JACEE ? Hard all-nucleon
spectrum?
6
TRACER(heavy nuclei only)
7
HESS Direct Cherenkov measurement of Fe spectrum
F. Aharonian et al. PR D75 042004 (2007) Method
proposed by Kieda, Swordy Wakely, 2001 Use ACT
on ground. Previously attempted from balloons,
Sood, 1983 Clem, Evenson, Seckel, 2002
8
H.E.S.S. Direct Cherenkov Fe spectrum measurement
Consistent with RUNJOB
9
Standard model of cosmic-rays to 100 TeV

• Diffusive shock acceleration in galactic SNR
• 15 of energy goes into accelerated p nuclei
• dN / dE E(-2.1) (source spectrum)
• secondary / primary nuclei ? tesc E(-0.6) to
  make dN / dE (observed) E(-2.7)
• Problems (e.g. Ptuskin et al., Jokipii)
• strong energy dependence of tesc violates
  observed isotropy when extrapolated to PeV
• observed turbulence prefers tesc E(-0.3)
• high efficiency ? non-linear acceleration ?
  event flatter source spectrum

10
Rigidity-dependence
Peters cycle systematic increase of lt A gt
approaching Emax

• Acceleration, propagation
• depend on B rgyro R/B
• Rigidity, R E/Ze
• Ec(Z) Z Rc
• rSNR parsec
• ? Emax Z 1015 eV
• 1 lt Z lt 30 (p to Fe)
• Slope change should occur within factor of 30 in
  energy
• With characteristic pattern of increasing A
• Problem continuation of smooth spectrum to EeV

B. Peters, Nuovo Cimento 22 (1961) 800
11
Composition in the knee region
SPASE-AMANDAB10, superimposed on data summary of
Swordy et al., Astropart. Phys. 18 (2002) 129.
EASTOP, M. Aglietta et al., Astropart. Phys. 20
(2004) 641
12
KASCADE Energy spectra for individual elemental
groups
SIBYLL
Andreas Haungs Aspen, 2005
QGSJET
H. Ulrich et al., Int. J. Mod. Phys. A (in press)
13
What interaction model to use?

• In KASCADE data, both QGSjet01 and SIBYLL have
  problem areas
• The greater energy reach of KASCADE-Grande may
  help unscramble this
• Xmax deeper in atmosphere, fluctuations less
  severe
• Gives a longer range of energy over which to test
  the models
• Hope to hear KASCADE-Grande results here at Aspen
  2007

14
Maximum energy for acceleration by SNR shocks

• Magnetic field amplification (Bell et al.) much
  discussed at Aspen 2005
• See paper of Hillas, for example.
• Emax gt PeV for protons no problem
• Non-linear diffusive shock acceleration
• H. Völk et al. (also Blasi et al.)
• Most of energy content may be near Emax
• Do we need a galactic component B

15
Cosmic-ray energy spectrum (Aspen, 2005)
J Hörandel
according to Astropart. Phys. 19 (2003) 193
16
HILLAS (Aspen, 2005)
17
Atoyan (Aspen, 2005)
Model GRB origin of CRs at and above the knee

• Cosmic Rays below 1014 eV from SNe that
  collapse to neutron stars
• Cosmic Rays above 1014 eV from SNe that
  collapse to black holes
• CRs between knee and ankle/second knee from GRBs
  in Galaxy
• CRs at higher energy from extragalactic/
  cosmological origin

(Wick et al. 2004)
18
TRANSITION
BEREZINSKY
The galactic component at E 11017 eV is
assumed to be iron nuclei. The spectrum is found
as difference of the total (observed) spectrum
and extragalactic proton spectrum (model). Ec is
considered as a free parameter in a range (0.3 -
2)1018 eV
19
(de) constructing the extra-galatic spectrum
dip (due to pair production)
End of Galactic population (not shown)
Doug Bergman et al. (HiRes), Proc 29th ICRC, 7
(2005) 315
20
Best USM Fit to HiRes
BERGMAN

• Fit USM varying m and g
• g 2.38
• m 2.55
• Galactic spectrum falls steeply above 100 PeV

Extragalactic
Galactic
21
Bahcall Waxman (GRB)
Physics Letters B556 (2003) 1

• Galactic? extragalactic transition 1019 eV
• Assume E-2 spectrum at source, normalize _at_ 1019.5
• 1045 erg/Mpc3/yr
• 1053 erg/GRB
• Evolution star-formation
• GZK losses included

Bahcall Waxman hep-ph/0206217
22
Transition lt 1018 eV
Transition at 1019 eV
N Busca, WG-4, Aug 29
Allard et al. astro-ph/0605327
23
Where is transition to extragalactic CR?
Stereo
24
Muon / electron ratio reflects nuclear
composition of primaries
Calculations of Ralph Engel, presented at Aspen,
April, 2005
25
Simulations Em at 2 km in IceCube vs Energy
deposited in tanks
Projection on mass axis
E
A
0.64, 0.8, 1.0, 5.0, 6.25, 10, 12.5 PeV
Projection on energy axis
26
AGASA, HiRes, Auger
Auger spectrum, from Paul Sommers talk at Pune
27
HiRes GZK cutoff (astro-ph/0703099)
E3 x differential spectrum
Integral spectrum / E-1.81
28
Lessons from the heliosphere

• ACE energetic particle fluences
• Smooth spectrum
• composed of several distinct components
• Most shock accelerated
• Many events with different shapes contribute at
  low energy (lt 1 MeV)
• Few events produce 10 MeV
• Knee Emax of a few events
• Ankle at transition from heliospheric to galactic
  cosmic rays

R.A. Mewaldt et al., A.I.P. Conf. Proc. 598
(2001) 165
29
Solar flare shock acceleration
Coronal mass ejection 09 Mar 2000
30
SOHO/ LASCO CME of 06-Nov 1997
31
LASCO event of 23 Nov 97
http//lasco-www.nrl.navy.mil/best_of_lasco_apr98/
index.htm
32
Heliospheric cosmic rays

• ACE--Integrated fluences
• Many events contribute to low-energy heliospheric
  cosmic rays
• fewer as energy increases.
• Highest energy (75 MeV/nuc) is dominated by
  low-energy galactic cosmic rays, and this
  component is again smooth
• Beginning of a pattern?

R.A. Mewaldt et al., A.I.P. Conf. Proc. 598
(2001) 165
33
Examples of power-law distributions(M.E.J.
Newman, cond-mat/0412004)
34
More examples from M.E.J. Newman, cond-mat/0412004
35
Casualties per attack in Iraq(Neil F. Johnson,
et al., from APS News, 8 Nov 2006)
Differential a 2.5
36
(No Transcript)
37
Three classes of sources
Presenter at this conference A (Rc,PV) B Extra- galactic Power
g 1 m required
Atoyan Galactic GRB ? ? ?
Berezinsky 2.5 None if Ec 0.3 PeV 2.7 0 3.5 x 1046 erg/Mpc3/yr, for Ec 1 PeV
Bergman - - 2.4 2.5 ?
Biermann - Wolf-Rayet SNR ? ? ?
Hillas 3 SNII into slow wind 2.3 3 ?
Hörandel 4 UH nuclei - - -
38
Outstanding issues

• Direct measurements for calibration
• Isotropy / propagation problem
• Non-linear acceleration ? hard spectrum
• How many sources?
• What interaction model to use?
• Is there a component B?
• Where is transition to extra-galactic