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Recent Results in Gamma Ray Astronomy with IACTs

Recent Results in Gamma Ray Astronomy with IACTs. Incontri di Fisica delle Alte Energie IFAE 2006 Pavia Vincenzo Vitale. Outline. Introduction Instruments and techniques Scientific highlights and observations Summary. Introduction. Cosmic gamma-ray observation:

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Recent Results in Gamma Ray Astronomy with IACTs

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  1. Recent Results in Gamma Ray Astronomy with IACTs Incontri di Fisica delle Alte Energie IFAE 2006 Pavia Vincenzo Vitale

  2. Outline • Introduction • Instruments and techniques • Scientific highlights and observations • Summary

  3. Introduction • Cosmic gamma-ray observation: - directly from satellites (HE) < O(10 GeV) and - indirectly from ground-based installations (VHE) > O(100 GeV) • Satellites: EGRET -> HE gamma-ray astronomy already consolidated. EGRET: Around 350 sources (250 unidentified)

  4. Ground based vs satellite • IACT/ground based • Secondary detection • huge effective area ~104 m2 • Higher sensitivity • small angular opening • small duty-cycle • low cost • high energy • high bkg • Satellite : • primary detection • small effective area ~1m2 • lower sensitivity • large angular opening • large duty-cycle • large cost • lower energy • low bkg

  5. Sensitivity of γdetectors High galactic latitudes(Fb=2 10-5g cm-2 s-1 sr -1 (100 MeV/E)1.1). Cerenkov telescopes sensitivities (Veritas, MAGIC, Whipple, Hess, Celeste, Stacee, Hegra) are for 50 hours of observations.Large field of view detectors sensitivities (AGILE, GLAST, Milagro, ARGO, AMS) are for 1 year of observation.

  6. VHEγdetectors TIBET MILAGRO MAGIC STACEE VERITAS TACTIC CANGAROO HESS TIBET ARGO-YBJ MILAGRO STACEE CACTUS TACTIC PACT GRAPES

  7. Particle shower ~ 10 km ~ 1o Cherenkov light ~ 120 m Observation tecnique Detection of TeV gamma rays using Cherenkovtelescopes

  8. Image intensity  Shower energy Image orientation  Shower direction Image shape  Primary particle

  9. Better bkgd reduction Better angular resolution Better energy resolution Slide fro Pr W. Hofmann

  10. Galactic Sources • Acceleration of Galactic cosmic rays in SNR • Galactic center emissions • New type of sources

  11. HESS galactic plane survey Sources > 6 sigma: 9 new, 11 total Sources > 4 sigma: 7 new • Most sources: • Shell-type SNR • Pulsar-Wind-Nebulae • Unidentified • New objects 330°

  12. RX J1713-3946 • Unambiguous evidence for particle acceleration in an SNR shell • Resolved shell in VHE g-rays • Close correlation between X-rays and g-rays

  13. RX J1713-3946 Preliminary  Acceleration of primary particles in SNR shock to well beyond 100 TeV • Index ~ 2.1 – 2.2 • Little variation across SNR • No evidence of cutoff or break at high energy

  14. Galactic Center Sgr A Diffuse emission Nature, Feb. 9th 2006

  15. Galactic Center Unbroken power law, index 2.3 Good agreement between HESS and MAGIC (large zenith angle observation).

  16. PSR B1259-63 • Binary system • Strong stellar wind • Shock at wind-pulsar interaction

  17. Extragalactic Sources • Physics of AGN jets • Cosmological extragalactic background light (EBL)

  18. AGN summary

  19. Extrag. Background Light • Cosmological radiation from star formation and evolution. • Spectral signature from gg absorption for Eg ~ 50-2000 GeV. • Use measured AGN spectra to constrain EBL. Gamma ray horizon Martinez et al 2005 1ES 1101-232 (HESS col.)

  20. AGN with orphan flares • Source observed already by Whipple and HEGRA in flaring state. • Orphan flares (hadronic origin ?) • MAGIC observation: low threshold and low flux (low state). • Two neutrinos in AMANDA data ?. • Two HiRes stereo events ?. • => Connection btw. Gamma-ray astronomy and neutrino/UHECR astronomy ?.

  21. Preliminary Preliminary Crab High resolution flare study • Huge Mkn 501 flare on 1st July 2005 -> 4 Crab intensity. • Intensity variation in 2 minute bins -> new, much stronger, constraints on emission mechanism and light-speed dispersion relations (effective quantum gravity scale). 2 minutes time bins

  22. GRBs observation with MAGIC • On 13 July 2005 MAGIC has observed a GRB with only 40 s delay • Preliminary analysis shows no signal • Constrain models on prompt emission

  23. The VHE γ ray sky 2005 + some additional sources in galactic plane. 1995 Mrk421 Mrk501 Crab Pulsar AGN

  24. Source Counts  Explosion in the number of VHE sources.

  25. Summary • Galactic Plane rich in number and type of VHE emitters. • PWN and SNRs firmly established as TeV sources. • Unprecedented spectrum and morphology studies. • Discovery of VHE gamma-ray emission from a binary Pulsar and from a Microquasar. • Wide-range spectrum of gamma-ray emission from GC. No hint for DM annihilation signals. • Increased number of TeV blazars at large redshift. Constraints in cosmological EBL. • 2 minutes-resolution light-curve of a fast flare. Constraints in emission models and light-speed dispersion relations. • First GRB follow-up in coincidence with X-ray observation. Constraints in GRB models.

  26. g CR (2) Shape:g –rays are narrower than cosmic rays. γ /hadron separation

  27. Proton shower Gamma shower γ /hadron separation Crab Nebula

  28. New Cherenkov Telescopes • VERITAS • 4x 12m telescopes at Kitt-Peak in 2006. MAGIC-II MAGIC-I • MAGIC-II • Improved 17m telescope. • Faster FADCs and a high-QE camera. • First light in 2007. 85m • HESS-II • New 28m telescope. • 2048 pixel camera. • Lower energy 40-50 GeV • First light in 2008.

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