Post on 05-Jan-2016
description
Results On VHE Gamma Ray Sources from ACTs and Air Shower Arrays
• HESS
• CANGAROO
• STACEE
• CELESTE
• MILAGRO
• TIBET – III Future Case Study from Other Sources
Results from Northern Sources from HESS
CELESTEBussons Gordo 2004Energy calibration under review!
H.E.S.S.H.E.S.S.
Significance Map
Object H.E.S.S. status
Crab Nebula ~50 (3 h), flux and spectrum agree
Mkn 421 ~80 (12 h), flux and spectrum ok
Mkn 501 not seen (~2 h); not detected by Whipple either at that time
Index 1.8Cutoff 2.4 TeV
H.E.S.S. & the “old” sources
PKS 2155
NGC 253
Gal. center
RX J 1713
SN 1006
Vela
PSR 1706-44
Object
H.E.S.S.: not detected at level of old fluxCANGAROO I I I : > 30 h of data under analysis
“A”
H.E.S.S.: not detected at level of old flux“B”
H.E.S.S.: 11 , spectrum differs
H.E.S.S.: 45 , spectrum & flux reasonable“B”
H.E.S.S.: 20 , spectrum & flux not incompatible“B+”
H.E.S.S.: not detected at level of old fluxCANGAROO I I I : > 30 h of data under analysis
“B”
H.E.S.S.: not detected at level of old flux“C”
Current status
Southern hemisphere TeV sources
PSR 1706-44• Spindown lum. ~ 1% of Crab
• X-ray lum. ~ 0.01% of Crab
• TeV emission detected by Durham and CANGAROO-I,II
Kifune et al. 1995Chadwick et al. 1998Kushida et al., ICRC 2003
PreliminaryICRC 2003
Crab Flux
E –2.2
E -1.2
Kifune, ICRC 2003
IC prediction ~0.001 CrabSefako & de Jager 2003, 2004
PSR 1706-44
Signalregion
2 (Degr.2)
14 h 2-telescope datataken during commissioningphase
H.E.S.S.assumingpoint source
preliminary
10-13
10-12
10-11
10-10
0,1 1 10
F [c
m-2
s-1]
E [TeV]
Integral Flux
CANGAROOYoshikoshi et al.
1997
DurhamChadwick et al.2000
H.E.S.S.2004assumingpoint source
E-1.5
VELA
• CANGAROO source 0.13o off pulsar
• H.E.S.S. limits similar for both CANGAROO and pulsar location
Chandra
preliminary
Classical southern SNRs
CANGAROO SN 1006
Kifune ICRC 2003
H.E.S.S. significance map
preliminary
Tanimori et al., ApJ 497 (1988) L253.8 m telescope+ conference proceedings
10-13
10-12
10-11
0,1 1 10 100
Inte
gral
Flu
x [c
m-2
s-1]
Energy [TeV]
CANGAROO 1996/97
HEGRA CT1 1999-2001
H.E.S.S. 99% UL2003 Datafor CANGAROO hotspot
with CANGAROO psf (0.23o)
H.E.S.S. flux limitsTime dependence ?
Size of SNR ~50 LYBut small scale shocks < 1 LY (Chandra)Need O(mG) fields to cool electrons quickly enough
Problem with theory ?(Berezhko, Völk)
Fields > 100 G reduce IC below limit Density < 0.1 cm-3 reduces o 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
preliminary
Index 2.84±0.15±0.20
TeV gamma rays from GC
Whipple 1995 – 20033.7
CANGAROO2001/2002> 10
Tsuchiya et al.200467 h on
Kosack et al. 200426 h
H.E.S.S.17 h datatight cutsno backgr.subtraction
CANGAROO Results on GC
Comparison of Spectrum from Different Experiments
on
off
Point source (size < 3‘ or 7 pc)
H.E.S.S.psf
H.E.S.S.Whipple(95%)
CANGAROO (80%)
none of the individual experiments sees variability
HESS and WHIPPLE see less flux than extrapolated
EGRET flux
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
Orbit► Period 3.4 years► Periastron 23 R*
► Apastron 331 R*
► Inclination 35°► Distance1.5 kpc point source► Last periastron 7th of March 2004
Only known object of this class in our galaxy! (not really true ????) (see Tavani’s talk in HD’04)
.
TeV gamma ray production viaInverse Compton Scattering of thestar’s photon field and acceleratedparticle populations from:
1) Unshocked pulsar wind Ball, Kirk 2000
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:► 26.2. - 2.3.2004► Livetime: 7.8 h► 3 telescopes only► Zenith angle: 42
deg► Threshold: 360
GeV
Post-periastron:► 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 post-
periastron spectrum is compatible
► HESS sees variability with RXT Observations
unshocked pulsar wind
log
(Flu
x [a
.u.])
days
shocked pulsar wind
aligned stellar disc
misaligned stellar disc
► Data does not favour continuous flux decrease within 21 days after periastron
► Systematics still under investigation
Lightcurve Shape –Data vs. Models
Looking For Other Sources in the Field of View
Results from the CELESTE Experiment
Results from the STACEE Experiment
Results from Air Shower ArraysMILAGRO and TIBET-III
(88.8,30.2)
Crab
Mrk421
DEC.
R.A.
Crab and MKn421 seen at significance of 4.9 and 5.3 sigma resp.Upper limits for several sources given
List of sky cells with clustered directions (24)having statistic significance larger than 4.0
TIBET-III
Large scale anisotropy of CR intensity with a magnitude of 0.1% has been observed
All Sky Coverage by MILAGRO
Full (northern)sky surveys
Energy Threshold ~ 1 TeVCrab and Mkn421 seen
For more details see the Milagro Talk at Heidelberg, 04
Old story we know
MILAGRO Observations Contd…….
Galactic Plane Survey
Galactic Centre obs showed 91 objectsthat 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 MicroquasarsRadio 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 obsRadio bursts on 26.5 day orbital circle
Modulation of X-ray emission on orbital timescales confirmedMost likely IC of stellar photons off electrons accelerated
at the shock boundary bet. relativistic wind of young pulsarand 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
• 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 observedHurley 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??