tom gaisser, leeds, july 23, 2004 in honor of alan watson the next 10 years in particle astrophysics...

Tom Gaisser, Leeds, July 23, 2004

in honor of Alan Watson

The next 10 years in Particle Astrophysics

Workshop summary

Some personal observations

Tribute to Alan



Solar flare shock acceleration

Coronal mass ejectionCoronal mass ejection 09 Mar 200009 Mar 2000



SOHO/LASCO

CME of 06-Nov 1997



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 (< 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



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



Knee

AnkleAnkle

Highest energy cosmic rays• Emax ~ shock 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, – 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?Extragalactic?

galacticgalactic



30

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 < Z < 30 (p to Fe)

• Slope change should occur within factor of 30 in energy

• Characteristic pattern of increasing A with energy



Direct measurements to 100 TeV:No major composition change

RUNJOB: thanks to T. ShibataATIC (preliminary): thanks to E-S Seo & J. Wefel



Recent Kascade data show increasing fraction of heavy nuclei 1015-3x1016 eV

Note anomalous He / proton ratio in recent Kascade analyses

K-H Kampert et al., astro-ph/0204205 ICRC 2001 (Hamburg)

M. Roth et al., Proc ICRC 2003 (Tsukuba) vol 1, p 139



Völk & Zirakashvili, 28th ICRC p. 2031

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 @ ~1 pc)

• What happens for E > 3x1016 eV?

Erlykin & Wolfendale, J Phys G27 (2001) 1005



Chem. Composition

AMANDA

1 km

2 km

SPASE-AMANDAAstropart. Phys. (2004)

AM

AN

DA

(nu

mbe

r o

f m

uons

)

Spase (number of electrons)

Iron

Proton

log(E/PeV)

SPASE(Bartol-Leeds)



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



Two DOMs: 10” PMTOne high-gain; one low-gain in each tank

To DAQ

IceCubeDrill Hole

~10-20 m

HG HG LGLG

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



PY03:4

PY04:12PY05:16

PY06:18

PY07:18

PY08:12

IIceCube Layout

100 m

Grid north

South Pole

Large showers with E ~ 100-1000 PeV will clarify transition from galactic to

extra-galactic cosmic rays.

Showers triggering 4 stations give ~300 TeV threshold for EAS array

Small showers (2-10 TeV) associated with the dominant background in the deep detector are detected as 2-tank coincidences at a station.Detection efficiency ~ 5% provides large sample to study this background



Test station deployed at South Pole November, 2003



Filling 03/04 test tanks

• Tank10 (1 m deep)– Filled Nov 22, 2003

• 20 minutes to fill

• < 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



Tanks closed Jan 23-26

a) Dec 6 during freeze (cover used as extra sun shade)

b) Jan 23 after closing, tent used as outer cover over

black vinyl sheeting

Tank10 during freeze and after closing



Feb 10/11, 2004

Tank 9 with telescope Tank 10

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



Primary composition with IceCube

• N from deep IceCube; Ne from IceTop

• High altitude allows good energy resolution

• Good mass separation from N/Ne

• 1/3 km2 sr (2000 x SPASE-AMANDA)

• Covers sub-PeV to EeV energies

Simulations of R. Engel



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 Thomson’s talk)



<ln(A)> = 0, E > 3 1016 eV

Protons

<ln(A)> = 4 ±2, E ~ 1015 eV

Elongation rate, Xmax & composition(Linsley & Watson 1981)

Xmax = 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



Change of composition at the ankle?

Original Fly’s Eye (1993): transition coincides with ankle

G. Archbold, P. Sokolsky, et al.,Proc. 28th ICRC, Tsukuba, 2003

HiRes new composition result: transition occurs before ankle



Exposure of giant arrays (as of ICRC-2003, thanks to M.Teshima)

1018-1019 eV threshold regime



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

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

• Normalize @ 1019 eV:CR = 2 x 10-19 erg/cm3

Power ~ CR / 1010 yrs

~ 1045 erg/Mpc3/yr

Uncertainties:• Normalization point:

1018 to 1019.5 usedFactor 10 / decade

• Spectral slope =2.3 for rel. shock = 2.0 non-rel.

• Emin ~ mp (shock)2



GRB model

• Assume E-2 spectrum at source, normalize @ 1019.5

• 1045 erg/Mpc3/yr• ~ 1053 erg/GRB• Evolution like star-formation

rate• GZK losses included• Galactic extragalactic

transition ~ 1019 eV

Bahcall & Waxman, hep-ph/0206217Waxman, astro-ph/0210638



Berezinsky et al. AGN

• Assuming a cosmological distribution of sources with:– dN/dE ~ E-2, E < 1018 eV– dN/dE ~ E, 1018< E < 1021

– = 2.7 (no evolution)– = 2.5 (with evolution)

• Need L0 ~ 3 ×1046 erg/Mpc3 yr

• They interpret dip at 1019 as– p + 2.7p + e+ + e-

Berezinsky, Gazizov, Grigorieva astro-ph/0210095



Plot from HiRes, astro-ph/0208301Plot from HiRes, astro-ph/0208301

Does spectrum exceed GZK?

• AGASA now finished– No sign of cutoff– Clusters10-5 sources/Mpc3

• HiRes– Consistent with GZK cutoff– No clustering observed

• Auger South– Should answer the question

within a year or so



UHECR Spectrum

Haverah Park Edge et al., 1973

1 event per km2

per century withE > 1020 eV



Connection to -rays and

• Talks of Völk, Hinton, Weekes, Mirzoyan

• Is there more than electron acceleration in GRB and AGN ?

• Zas: p/ as a probe of top-down vs acceleration models of UHECR – Also probes evolution of sources



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 UHE

Matter Distribution 7 Mpc < D < 21 Mpc

Cronin astro-ph/0402487 [Kravtsov]



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



Power needed for extragalactic cosmic rays assuming transition at 1019 eV

• Energy density in UHECR, CR ~ 2 x 10 erg/cm3

– Such an estimate requires extrapolation of UHECR to low energy CR = (4/c) E(E) dE = (4/c){E2(E)}E=1019eV x ln{Emax/Emin}

– This gives CR ~ 2 x 10 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 signal ~ 10 to 100/km2yr

– ~20% have E>50 TeV (greater than atmospheric background)



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



Remote operation of DOMs



Energy-dependence of secondary/primary cosmic-ray

nuclei • B/C ~ E-0.6

• Observed spectrum:– (E) = dN/dE ~ K E-2.7

• Interpretation:– Propagation depends on E– (E) ~ E-0.6

– (E) ~ Q(E) x (E) x (c/4)

• Implication:– Source spectrum Q(E) ~ E-

2.1



Problems of simplest SNR shock model

• Expected shape of spectrum:– Differential index ~ 2.1 for

diffusive shock acceleration• observed ~ 2.7source ~2.1;

~ 0.6 esc(E) ~ E-0.6

• c esc Tdisk ~100 TeV

Isotropy problem

• Emax ~ shock Ze x B x Rshock

Emax ~ Z x 100 TeV with exponential cutoff of each component

– But spectrum continues to higher energy:

Emax problem

• Expect p + gas (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 0 -rays



Speculation on the knee

K-H Kampert et al., astro-ph/0204205

3 components

Total

protonshelium

CNOMg…

Fe



UHECR spectrum

Haverah Park, Edge et al., 1973

tom gaisser, leeds, july 23, 2004 in honor of alan watson the next 10 years in particle astrophysics...

Documents