Tom Gaisser,

1
The next 10 years in Particle Astrophysics

• Workshop summary
• Some personal observations
• Tribute to Alan

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Solar flare shock acceleration
Coronal mass ejection 09 Mar 2000
3
SOHO/ LASCO CME of 06-Nov 1997
4
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
5
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
6
Highest energy cosmic rays

• Emax bshock Ze x B x Rshock for SNR
• ? Emax Z x 100 TeV
• Many potential sources
• Knee region
• Differential spectral index changes at 3 x
  1015eV, a 2.7 ? a 3.0
• Some SNR can accelerate protons to 1015 eV
  (Berezhko Völk)
• 1016 to 1018 eV a few special sources?
  Reacceleration?
• Ankle at 3 x 1018 eV
• Flatter spectrum
• Suggestion of change in composition
• New population of particles, possibly
  extragalactic?
• Look for composition signatures of knee and
  ankle

Extragalactic?
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Rigidity-dependence

• 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
• Characteristic pattern of increasing A with energy

8
Direct measurements to 100 TeVNo major
composition change
RUNJOB thanks to T. Shibata ATIC (preliminary)
thanks to E-S Seo J. Wefel
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Recent Kascade data show increasing fraction of
heavy nuclei 1015-3x1016 eV
M. Roth et al., Proc ICRC 2003 (Tsukuba) vol 1,
p 139
Note anomalous He / proton ratio in recent
Kascade analyses
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Galactic models of knee beyond conspiracy or
accident?

• Axford
• continuity of spectrum over factor 300 of energy
  implies relation between acceleration mechanisms
• reacceleration by multiple SNR
• Völk
• reacceleration by shocks in galactic wind
  (analogous to CIRs in heliosphere)
• Erlykin Wolfendale
• Local source at knee on top of smooth galactic
  spectrum
• (bending of background could reflect change
  in diffusion _at_ 1 pc)
• What happens for E gt 3x1016 eV?

11
Chem. Composition
Chemical Composition
SPASE (Bartol-Leeds)
SPASE-AMANDA Astropart. Phys. (2004)
AMANDA
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Rates of contained, coincident events in IceCube
Area--solid-angle 1/3 km2sr (including angular
dependence of EAS trigger)
3000 x aperture of SPASE-AMANDA
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IceTop station

• Two Ice Tanks 3 m2 x 0.9 m deep (scaled down from
  Haverah, Auger)
• Integrated with IceCube same hardware, software
• Coincidence between tanks potential air shower
• Signal in single tank potential muon
• Significant area for horizontal muons
• Low Gain/High Gain operation to achieve dynamic
  range
• Two DOMs/tank gives redundancy against failure
  of any single DOM
• because only 1 low-gain detector is needed per
  station

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Large showers with E 100-1000 PeV will clarify
transition from galactic to extra-galactic
cosmic rays.
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Test station deployed at South Pole November, 2003
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Filling 03/04 test tanks

• Tank10 (1 m deep)
• Filled Nov 22, 2003
• 20 minutes to fill
• lt 10 RPSC man hours for transport and filling
• Tank09 ( 0.9 m )
• Filled Nov 26, 2003
• Freeze time 60 days
• 40 days planned
• Plan revised to finish freeze after closing tank

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Tanks closed Jan 23-26
Tank10 during freeze and after closing
b) Jan 23 after closing, tent used as outer
cover over black vinyl sheeting
a) Dec 6 during freeze (cover used as extra sun
shade)
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Feb 10/11, 2004
Tank 9 with m telescope
Tank 10

• Remote operation since February
• pre-pre-production DAQ and main board
• monitoring temperatures during austral winter
• limited muon data

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Primary composition with IceCube

• Nm from deep IceCube Ne from IceTop
• High altitude allows good energy resolution
• Good mass separation from Nm/Ne
• 1/3 km2 sr (2000 x SPASE-AMANDA)
• Covers sub-PeV to EeV energies

Simulations of R. Engel
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Transition from Galactic to Extra-galactic origin?

• Where is the transition? (Hillas talk)
• Composition signature
• From mostly heavy primaries at end of galactic
  origin to large fraction of protons
• Continuous coverage over a large energy range
  would be helpful (G Thomsons talk)

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Elongation rate, Xmax composition(Linsley
Watson 1981)
Xmax l ln(E0/A) B
Analysis of fluctuations in rise-time,
1973 departure of individual showers from the
mean behaviour most readily understood if some
of the primary particles of energy E 1018 eV
are light, probably protons ---A.A. Watson
J.G. Wilson, 1974
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Change of composition at the ankle?
Stereo
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Exposure of giant arrays (as of ICRC-2003,
thanks to M.Teshima)
1018-1019 eV threshold regime
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More questions about UHECR

• What are the sources GRB? (Waxman), AGN?
  (Berezinsky), Top-down? (Sigl)
• Does spectrum continue past GZK limit?
• What is the distribution of sources?
  Medina-Tanco, Olinto, Sommers
• Clustering? How many sources?
• Point sources?
• Galactic halo distribution?
• Importance of magnetic fields?
• Need all-sky coverage for full picture

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Energy content of extra-galactic component
depends on location of transition

• Normalize _at_ 1019 eV
• rCR 2 x 10-19 erg/cm3
• Power rCR / 1010 yrs
• 1045 erg/Mpc3/yr
• Uncertainties
• Normalization point
• 1018 to 1019.5 used
• Factor 10 / decade
• Spectral slope
• a2.3 for rel. shock
• 2.0 non-rel.
• Emin mp (gshock)2

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GRB model
Bahcall Waxman, hep-ph/0206217 Waxman,
astro-ph/0210638

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

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Berezinsky et al. AGN

• Assuming a cosmological distribution of sources
  with
• dN/dE E-2, E lt 1018 eV
• dN/dE E-g, 1018lt E lt 1021
• g 2.7 (no evolution)
• g 2.5 (with evolution)
• Need L0 3 1046 erg/Mpc3 yr
• They interpret dip at 1019 as
• p g2.7? p e e-

Berezinsky, Gazizov, Grigorieva astro-ph/0210095
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Does spectrum exceed GZK?

• AGASA now finished
• No sign of cutoff
• Clusters?10-5 sources/Mpc3
• HiRes
• Consistent with GZK cutoff
• No clustering observed
• Auger South
• Should answer the question within a year or so

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UHECR Spectrum
1 event per km2 per century with E gt 1020 eV
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Connection to g-rays and n

• Talks of Völk, Hinton, Weekes, Mirzoyan
• Is there more than electron acceleration in GRB
  and AGN ?
• Zas p/n as a probe of top-down vs acceleration
  models of UHECR
• Also probes evolution of sources

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New experiments

• Telescope array
• Auger North
• EUSO
• Neutrino telescopes
• AMANDA, Baikal continue in short term
• ANTARES ( Nestor) in 2005, 2006?
• IceCube
• Km3 in Mediterranean
• Radio detection for UHEn

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Matter Distribution 7 Mpc lt D lt 21 Mpc
Cronin astro-ph/0402487 Kravtsov
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Closing remarks

• Thanks to
• Johannes, Jeremy and colleagues
• to Carol Ward and Maria
• to Mansukh Patel
• Thanks to Auger Collaboration for a great
  experiment
• Best wishes to Alan for future science

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Power needed for extragalactic cosmic rays
assuming transition at 1019 eV

• Energy density in UHECR, ?CR 2 x 10-19 erg/cm3
• Such an estimate requires extrapolation of UHECR
  to low energy
• ?CR (4?/c) ? E?(E) dE (4?/c)E2?(E)?E1019eV
  x lnEmax/Emin
• This gives ?CR 2 x 10-19 erg/cm3 for
  differential index ? 2, ?(E) E-2
• Power required ?CR/1010 yr 1045 erg/Mpc3/yr
• Estimates depend on cosmology and extragalactic
  magnetic fields
• 3 x 10-3 galaxies/Mpc3 5 x 1039 erg/s/Galaxy
• 3 x 10-6 clusters/Mpc3 4 x 1042 erg/s/Galaxy
  Cluster
• 10-7 AGN/Mpc3 1044 erg/s/AGN
• 1000 GRB/yr 3 x 1052 erg/GRB
• Assume E?-2 spectrum. Then n signal 10 to
  100/km2yr
• 20 have E?gt50 TeV (greater than atmospheric
  background)

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Remote operation of DOMs

• Pre-production main boards pre-production DAQ
• Use SPASE GPS clock for time stamp
• Slow readout (large dead-time)
• No local coincidence
• Study main board temperatures during austral
  winter

36
Remote operation of DOMs
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Energy-dependence of secondary/primary cosmic-ray
nuclei

• B/C E-0.6
• Observed spectrum
• f(E) dN/dE K E-2.7
• Interpretation
• Propagation depends on E
• t(E) E-0.6
• f(E) Q(E) x t(E) x (c/4p)
• Implication
• Source spectrum Q(E) E-2.1

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Problems of simplest SNR shock model

• Expect p gas ? g (TeV) for certain SNR
• Need nearby target as shown in picture from
  Nature (April 02)
• Interpretation uncertain see
• Enomoto et al., Aharonian (Nature) Reimer et
  al., astro-ph/0205256
• ? Problem of elusive p0 g-rays

• Expected shape of spectrum
• Differential index a 2.1 for diffusive shock
  acceleration
• aobserved 2.7 asource 2.1 Da 0.6 ?
  tesc(E) E-0.6
• c tesc ? Tdisk 100 TeV
• ? Isotropy problem
• Emax bshock Ze x B x Rshock
• ? Emax Z x 100 TeV with exponential cutoff of
  each component
• But spectrum continues to higher energy
• ? Emax problem

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Speculation on the knee
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UHECR spectrum