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Results On VHE Gamma Ray Sources from ACTs and Air Shower Arrays

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. CELESTE Bussons Gordo 2004 Energy calibration under review!. H.E.S.S. Significance Map. Index 1.8 Cutoff 2.4 TeV.

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Results On VHE Gamma Ray Sources from ACTs and Air Shower Arrays

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  1. ResultsOn VHE Gamma Ray Sources from ACTs and Air Shower Arrays • HESS • CANGAROO • STACEE • CELESTE • MILAGRO • TIBET – III Future Case Study from Other Sources

  2. CELESTE Bussons Gordo 2004 Energy calibration under review! H.E.S.S. Significance Map Index 1.8 Cutoff 2.4 TeV Results from Northern Sources from HESS

  3. PSR 1706-44 Kifune, ICRC 2003 • Spindown lum. ~ 1% of Crab • X-ray lum. ~ 0.01% of Crab • TeV emission detected by Durham and CANGAROO-I,II Kifune et al. 1995 Chadwick et al. 1998 Kushida et al., ICRC 2003 Preliminary ICRC 2003 E -1.2 Crab Flux IC prediction ~0.001 Crab Sefako & de Jager 2003, 2004 E –2.2

  4. preliminary H.E.S.S. assuming point source PSR 1706-44 Signal region q2 (Degr.2) 14 h 2-telescope data taken during commissioning phase

  5. preliminary VELA -10 10 Integral Flux • CANGAROO source 0.13o off pulsar • H.E.S.S. limits similar for both CANGAROO and pulsar location Durham Chadwick et al. 2000 E-1.5 -11 10 CANGAROO Yoshikoshi et al. 1997 ] -1 s -2 F [cm Chandra H.E.S.S. 2004 assuming point source -12 10 -13 10 0,1 1 10 E [TeV]

  6. H.E.S.S. significance map preliminary Classical southern SNRs CANGAROO SN 1006 Kifune ICRC 2003 Tanimori et al., ApJ 497 (1988) L25 3.8 m telescope + conference proceedings

  7. -11 10 CANGAROO s-1] 1996/97 -2 -12 10 HEGRA CT1 Integral Flux [cm 1999-2001 H.E.S.S. 99% UL -13 10 2003 Data for CANGAROO hotspot o with CANGAROO psf (0.23 ) 0,1 1 10 100 Energy [TeV] H.E.S.S. flux limits • Time dependence ? • Size of SNR ~50 LY • But small scale shocks < 1 LY (Chandra) • Need O(mG) fields to cool electrons quickly enough • Problem with theory ? • (Berezhko, Völk) • Fields > 100 mG reduce IC below limit • Density < 0.1 cm-3 reduces po component below limit

  8. H.E.S.S. Classical southern SNRs CANGAROO RXJ1713.7-3946 Kifune ICRC 2003

  9. 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

  10. H.E.S.S. 17 h data tight cuts no backgr. subtraction TeV gamma rays from GC Kosack et al. 2004 26 h Tsuchiya et al. 2004 67 h on CANGAROO 2001/2002 > 10 s Whipple 1995 – 2003 3.7 s

  11. CANGAROO Results on GC

  12. H.E.S.S. 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

  13. . 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 withP = 48 ms • Spin down luminosityLp = 8.1028 W Only known object of this class in our galaxy! (not really true ????) (see Tavani’s talk in HD’04) Orbit • Period 3.4 years • Periastron 23 R* • Apastron 331 R* • Inclination 35° • Distance 1.5kpc 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: Unshocked pulsar wind Ball, Kirk 2000 Pulsar wind termination shock induced by star’s photon field Ball, Dodd 2001 Interaction region of star mass outflow and pulsar wind Kawachi et al. 2004

  14. CANGAROO Observations HESS Observations Schedule Pre-periastron: • 26.2. - 2.3.2004 • Livetime: 7.8h • 3 telescopes only • Zenith angle: 42deg • Threshold: 360 GeV Post-periastron: • 19.3. - 29.3.2004 • Livetime: 17.4h • Zenith angle: 44deg • Threshold: 380 GeV

  15. Preliminary Analysis Results -Signal Pre-periastron, 7.8h: • Significance: 9.1σ • Excess rate: (0.39±0.04) /min Post-periastron, 17.4h: • Significance: 6.3σ • Excess rate: (0.22±0.03) /min

  16. Significance Skymap: • FoV = 2deg 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

  17. 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 misaligned stellar disc days

  18. Looking For Other Sources in the Field of View

  19. Results from the CELESTE Experiment

  20. Results from the STACEE Experiment

  21. Mrk421 Crab Results from Air Shower ArraysMILAGRO and TIBET-III DEC. TIBET-III (88.8,30.2) R.A. 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

  22. 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

  23. MILAGRO Observations Contd…….

  24. Galactic Plane Survey

  25. Galactic Centre obs showed 91 objects that accounts for 90% of > 20 KeV bgd towards the centre of galaxy

  26. For more details, see talk by R.Much at HD’04

  27. 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

  28. 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.

  29. 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)

  30. 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 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??

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