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Results On VHE Gamma Ray Sources from
ACTs and Air Shower Arrays
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HESS
CANGAROO
STACEE
CELESTE
MILAGRO
TIBET – III
Future Case Study from Other
Sources
Results from Northern Sources from HESS
Object
Crab Nebula
Mkn 421
H.E.S.S. status
~50 s (3 h), flux
and spectrum agree
~80 s (12 h), flux
and spectrum ok
Index 1.8
Cutoff 2.4 TeV
Mkn 501
not seen (~2 h); not
detected by
Whipple either at
that time
CELESTE
Bussons Gordo 2004
Energy calibration under review!
H.E.S.S.
Significance Map
PSR 1706-44
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Spindown lum. ~ 1% of Crab
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X-ray lum.
Crab
•
TeV emission detected by Durham
and CANGAROO-I,II
Kifune et al. 1995
Chadwick et al. 1998
Kushida et al., ICRC 2003
Kifune, ICRC 2003
~ 0.01% of
IC prediction ~0.001 Crab
Sefako & de Jager 2003, 2004
Preliminary
ICRC 2003
E -1.2
Crab Flux
E –2.2
PSR 1706-44
preliminary
Signal
region
q2 (Degr.2)
14 h 2-telescope data
taken during commissioning
phase
H.E.S.S.
assuming
point source
preliminary
VELA
-10
10
Integral Flux
E-1.5
CANGAROO
Yoshikoshi et al.
1997
-2 -1
F [cm s ]
-11
10
Durham
Chadwick et al.
2000
Chandra
• CANGAROO source
0.13o off pulsar
• H.E.S.S. limits
similar for both
CANGAROO and
pulsar location
H.E.S.S.
2004
-12
10
assuming
point source
-13
10
0,1
1
E [TeV]
10
Classical southern SNRs
CANGAROO SN 1006
Kifune ICRC 2003
Tanimori et al., ApJ 497 (1988) L25
3.8 m telescope
+ conference proceedings
H.E.S.S. significance map
preliminary
H.E.S.S. flux limits
Time dependence ?
-11
CANGAROO
1996/97
-2
Integral Flux [cm s-1]
10
-12
10
HEGRA CT1
1999-2001
-13
10
o
with CANGAROO psf (0.23)
1
Problem with theory ?
(Berezhko, Völk)
H.E.S.S. 99% UL
2003 Data
for CANGAROO hotspot
0,1
Size of SNR ~50 LY
But small scale shocks
< 1 LY (Chandra)
Need O(mG) fields to cool
electrons quickly enough
10
Energy [TeV]
100
Fields > 100 mG reduce IC
below limit
Density < 0.1 cm-3 reduces
po component below limit
Classical southern SNRs
CANGAROO RXJ1713.7-3946
Kifune ICRC 2003
H.E.S.S.
RJX1713 Spectrum,
HESS analysed 18 hrs of 2003 data, Hard Cuts and No
Background Subtraction
H.E.S.S.: full remnant
CANGAROO: hotspot
Index 2.2±0.07±0.1
Index
2.84±0.15±0.20
preliminary
TeV gamma rays from GC
Tsuchiya et al.
2004
67 h on
Kosack et al. 2004
26 h
H.E.S.S.
17 h data
tight cuts
no backgr.
subtraction
CANGAROO
2001/2002
> 10 s
Whipple
1995 – 2003
3.7 s
CANGAROO Results on GC
Comparison of Spectrum from
Different Experiments
none of the individual experiments sees variability
on
off
H.E.S.S.
psf
Point source
(size < 3‘ or 7 pc)
CANGAROO (80%)
Whipple
(95%)
HESS and WHIPPLE
see less flux than extrapolated
EGRET flux
H.E.S.S.
PSR B1259-63 / SS 2883 System Outline
Star
► Bright and massive Be-star:
L* = 3 .1030 W, M = 10 M .
► Stellar disk, mass outflow
Pulsar
► Radio pulsar with
P = 48 ms
► Spin down luminosity
Lp = 8 .1028 W
Only known object of this class in our galaxy! (not really
true ????) (see Tavani’s talk in HD’04)
Orbit
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Period
3.4 years
Periastron
23 R*
Apastron
331 R*
Inclination
35°
Distance
1.5 kpc  point source
Last periastron 7th of March 2004
TeV gamma ray production via
Inverse Compton Scattering of the
star’s photon field and accelerated
particle populations from:
1)
Unshocked pulsar wind
2000
Ball, Kirk
2)
Pulsar wind termination shock
induced by star’s
photon field
Ball, Dodd 2001
3)
Interaction region of star mass
outflow and
pulsar wind
Kawachi et al. 2004
CANGAROO Observations
HESS Observations Schedule
Pre-periastron:
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26.2. - 2.3.2004
Livetime:
7.8 h
3 telescopes only
Zenith angle: 42 deg
Threshold:
360 GeV
Post-periastron:
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19.3. - 29.3.2004
Livetime:
17.4 h
Zenith angle: 44 deg
Threshold:
380 GeV
Preliminary Analysis Results - Signal
Pre-periastron, 7.8 h:
► Significance: 9.1 σ
► Excess rate:
(0.39 ± 0.04) /min
Post-periastron, 17.4 h:
► Significance: 6.3 σ
► Excess rate:
(0.22 ± 0.03) /min
Significance Skymap:
► FoV = 2 deg radius
► Clear excess at pulsar
position
Spectrum Fit:
► Spectral index:
-2.8 ± 0.3 (stat)
► Flux level:
5% Crab
► Spectral index of postperiastron spectrum is
compatible
► HESS sees variability
with RXT Observations
log(Flux [a.u.])
Lightcurve
Shape –
Data vs.
Models
unshocked pulsar wind
► Data does not
favour continuous
flux decrease within
21 days after
periastron
► Systematics still
under investigation
shocked pulsar wind
aligned stellar disc
days
Looking For Other Sources in the Field of View
Results from the CELESTE Experiment
Results from the STACEE Experiment
Results from Air Shower Arrays
MILAGRO and TIBET-III
DEC.
Mrk421
TIBET-III
(88.8,30.2)
Crab
List of sky cells with clustered
directions (24)having statistic
significance larger than 4.0
Crab and MKn421 seen at significance of 4.9 and 5.3 sigma resp.
Upper limits for several sources given
Large scale anisotropy of CR intensity with a magnitude of 0.1%
has been observed
R.A.
All Sky Coverage by MILAGRO
Old story we know
Full (northern)
sky surveys
Energy Threshold ~ 1 TeV
Crab and Mkn421 seen
For more details see the Milagro Talk at Heidelberg, 04
MILAGRO Observations Contd…….
Galactic Plane Survey
Galactic Centre obs showed 91 objects
that accounts for 90% of > 20 KeV bgd
towards the centre of galaxy
For more details, see talk by R.Much at HD’04
Some Thoughts for the Future Sources
High Energy Processes from Microquasars
Radio Emitting X-ray binaries
A few sources detected simultaneously in X-ray/radio bands
Merck et al ( 1996) studied spectral characteristics
of unidentified galactic EGRET sources
Most of them have hard spectrum and extend to GeV energies
Could be Pulsar like !!!!!!
Spectra does not seem to be identical to the identified pulsars
High galactic diffuse background make analysis difficult
Be Binary system LS I +61deg 303 (associated with GT 0236 +610)
Possible emission with 100 MeV gamma ray source, 2CG135 +01
Simultaneous radio and RXTE obs
Radio bursts on 26.5 day orbital circle
Modulation of X-ray emission on orbital timescales confirmed
Most likely IC of stellar photons off electrons accelerated
at the shock boundary bet. relativistic wind of young pulsar
and Be star wind.
Multiwavelength Studies of AGNs
There were quite a few talks, but no new results or theories as such
People still want more data and more co-ordinated observations
to distinguish between ‘hadronic’ and ‘leptonic’ model
(see papers by Costamante and Ghisellini, A&A, 384, 56-71(2002)
High Energy Components of GRBs
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GRB association with SNe is confirmed in at least a few cases ( GRB0300329-Sn2003dh )
Physics of jet creation, acceleration, propagation and evolution to be understood
Correlations of MeV energy with global jet parameters imply MeV to be dominant
However in the standard scenario a large fraction of energy is expected in the afterglow phase
And in several GRBs powerful >> MeV components are observed
Hurley et al. 1994 discover
high energy component with
EGRET
High energy photons last
much longer than MeV
emission
Also Gonsalez et al(2003) discovered in EGRET archive a GRB whose prompt
Energy emission is dominated by E>> 200 MeV, MILAGRO discovered a TeV burst at 3.0 sigma level
Can one do cosmography with GRBs ?
Check for possible evolution of cosmological constant??