Transcript The next 10 years in Particle Astrophysics Workshop summary Some personal observations

The next 10 years in Particle
Astrophysics
Workshop summary
Some personal observations
Tribute to Alan
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Solar flare shock acceleration
Coronal mass ejection
09 Mar 2000
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
SOHO/
LASCO
CME of
06-Nov
1997
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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
Tom Gaisser,
Leeds, July 23, 2004
R.A. Mewaldt et al., A.I.P. Conf. Proc. 598 (2001) 165
in honor of Alan Watson
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.
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
598 (2001) 165
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?
Knee
galactic
• 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”
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Ankle
Extragalactic?
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
30
Direct measurements to 100 TeV:
No major composition change
RUNJOB: thanks to T. Shibata
ATIC (preliminary): thanks to E-S Seo & J. Wefel
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Recent Kascade data show increasing
fraction of heavy nuclei 1015-3x1016 eV
M. Roth et al., Proc ICRC 2003 (Tsukuba)
vol 1, p 139
K-H Kampert et al., astro-ph/0204205
ICRC 2001 (Hamburg)
Note anomalous He / proton ratio
in recent Kascade analyses
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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)
Völk & Zirakashvili, 28th ICRC p. 2031
• 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?
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Erlykin & Wolfendale, J Phys G27 (2001) 1005
Chem.
Composition
(Bartol-Leeds)
SPASE
AMANDA (number of muons)
1 km
Iron
Proton
Spase (number of electrons)
AMANDA
2 km
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Rates of contained, coincident events
in IceCube
2
Area--solid-angle ~ 1/3 km sr
3000 x aperture of SPASE-AMANDA
Tom Gaisser,
Leeds, July 23, 2004
(including angular dependence of EAS trigger)
in honor of Alan Watson
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
To DAQ
Two DOMs: 10” PMT
One high-gain; one low-gain in each tank
IceCube
Drill Hole
LG
HG
HG
~10-20 m
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
LG
IceCube
Layout
I
Showers triggering 4 stations give
~300 TeV threshold for EAS array
PY05:16
100 m
PY04:12
Large showers with E ~ 100-1000 PeV
will clarify transition from galactic to
extra-galactic cosmic rays.
PY06:18
PY03:4
PY08:12
Small showers (2-10 TeV)
PY07:18
associated with the dominant
m background in the deep detector are
detected as 2-tank coincidences at a station.
Detection efficiency ~ 5%
provides large sample to study this background
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
South
Pole
Grid
north
Test station deployed at South Pole November, 2003
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Tanks closed Jan 23-26
Tank10 during freeze and after closing
a) Dec 6 during freeze
(cover used as extra sun shade)
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
b) Jan 23 after closing, tent
used as outer cover over
black vinyl sheeting
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Simulations of R. Engel
Transition from Galactic to Extragalactic 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)
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Elongation rate, Xmax & composition
(Linsley & Watson 1981)
Xmax = l ln(E0/A) + B
<ln(A)> = 0, E > 3 1016 eV
Protons
<ln(A)> = 4 ±2, E ~ 1015 eV
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Change of composition at the ankle?
Original Fly’s Eye (1993):
transition coincides with ankle
Tom Gaisser,
Leeds, July 23, 2004
HiRes new composition result:
transition occurs before ankle
in honor of Alan Watson
G. Archbold, P. Sokolsky, et al.,
Proc. 28th ICRC, Tsukuba, 2003
Exposure of giant arrays
(as of ICRC-2003, thanks to M.Teshima)
1018-1019 eV threshold regime
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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? – MedinaTanco, Olinto, Sommers
–
–
–
–
Clustering? – How many sources?
Point sources?
Galactic halo distribution?
Importance of magnetic fields?
• Need all-sky coverage for full picture
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Energy content of extra-galactic component
depends on location of transition
• Normalize @ 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
a=2.3 for rel. shock
= 2.0 non-rel.
• Emin ~ mp (gshock)2
GRB model
Bahcall & Waxman, hep-ph/0206217
Waxman, astro-ph/0210638
• Assume E-2 spectrum at
source, normalize @
1019.5
• 1045 erg/Mpc3/yr
• ~ 1053 erg/GRB
• Evolution like starformation rate
• GZK losses included
• Galactic extragalactic
Tom Gaisser,
in honor of Alan Watson
19 eV
transition
~
10
Leeds, July 23, 2004
Berezinsky et al.
AGN
• Assuming a cosmological
distribution of sources with:
–
–
–
–
dN/dE ~ E-2, E < 1018 eV
dN/dE ~ E-g, 1018< E < 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+ + eTom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Berezinsky, Gazizov, Grigorieva
astro-ph/0210095
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Plot from HiRes, astro-ph/0208301
UHECR Spectrum
1 event per km2
per century with
E > 1020 eV
Tom Gaisser,
Leeds, July 23, 2004
Haverah Park
Edge et al., 1973
in honor of Alan Watson
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
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
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Power needed for extragalactic cosmic
rays assuming transition at 1019 eV
• Energy density in UHECR, rCR ~ 2 x 10-19 erg/cm3
– Such an estimate requires extrapolation of UHECR to low energy
– rCR = (4/c)  E(E) dE = (4/c){E2(E)}E=1019eV x ln{Emax/Emin}
– This gives rCR ~ 2 x 10-19 erg/cm3 for differential index a = 2, (E) ~ E-2
• Power required ~ rCR/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 En-2 spectrum. Then n signal ~ 10 to 100/km2yr
– ~20% have Em>50 TeV (greater than atmospheric background)
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Remote operation of DOMs
• Pre-production main
boards; preproduction DAQ
– Use SPASE GPS
clock for time stamp
– Slow readout (large
dead-time)
• No local coincidence
• Study main board
temperatures during
austral winter
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Remote operation of DOMs
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Energy-dependence of
secondary/primary cosmic-ray
nuclei
-0.6
• B/C ~ E
• Observed spectrum:
– (E) = dN/dE ~ K E-2.7
• Interpretation:
– Propagation depends on E
– t(E) ~ E-0.6
– (E) ~ Q(E) x t(E) x (c/4)
• Implication:
– Source spectrum Q(E) ~
E-2.1
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
Problems of simplest SNR shock
model
• Expect p + gas  g (TeV) for
certain SNR
• 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
– Need nearby target as shown
in picture from Nature (April 02)
– Interpretation uncertain; see
•
•
–  Problem of elusive 0 g-rays
• 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
Tom Gaisser,
Leeds, July 23, 2004
Enomoto et al., Aharonian (Nature);
Reimer et al., astro-ph/0205256
in honor of Alan Watson
Speculation on the knee
Total
protons
Fe
helium
CNO
Mg…
3 components
a=2.7
a=2.4
K-H Kampert et al., astro-ph/0204205
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson
UHECR spectrum
Haverah Park, Edge et al., 1973
Tom Gaisser,
Leeds, July 23, 2004
in honor of Alan Watson