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Gamma-ray Astronomy

Gamma-ray Astronomy. (The Short Story…). The Big Picture. Whole sky glows Extreme environments Probes of the Universe. CGRO/EGRET All Sky Map. Explorer 11. Early Gamma-ray Astronomy. • Gamma-ray Bursts Vela Program : A Bomb or Not a Bomb? A few hundred events, a few hundred theories

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Gamma-ray Astronomy

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  1. Gamma-ray Astronomy (The Short Story…)

  2. The Big Picture • Whole sky glows • Extreme environments • Probes of the Universe CGRO/EGRET All Sky Map

  3. Explorer 11

  4. Early Gamma-ray Astronomy • • Gamma-ray Bursts • Vela Program : A Bomb or Not a Bomb? • A few hundred events, a few hundred theories • Gamma-ray Sources • SAS-2 – discovered 2 pulsars (1972) • COS-B – about 25 sources(1975-82) • Most unidentified, but 1 quasar • Diffuse extra-galactic background

  5. Vela Program (1969-1979)

  6. OSO 3

  7. HEAO 3

  8. Cos-B (1975-1982)

  9. GRANAT

  10. CGRO (1991-2000)

  11. Sources of g-ray Emission • Black holes • Active Galaxies • Pulsars •Gamma-ray bursts • Diffuse emission • Supernovae • Unidentified

  12. BATSE

  13. Gamma-Ray Bursts

  14. Distribution of GRBs in the Sky

  15. OSSE

  16. The Galactic Center Region

  17. Antimatter Fountain in the Center of Milky Way

  18. COMPTEL

  19. 26Al COMPTEL sky map

  20. EGRET

  21. CGRO/EGRET • Apr 1991 – Jun 2000 • 30 MeV – 30 GeV • 67%=5.85(100 MeV/E)0.534

  22. The Third Egret Catalog E >100 MeV • EGRET cycles 1-4: 416 gamma-ray excesses above 3 sigma. • 271 of them included in the 3EG catalog. • The significance of sources close to the Galactic plane is 5 sigma. Sources off the the plane have 4 sigma.

  23. High Energy Halo around Milky Way Courtesy of D. Dixon, University of California, Riverside

  24. Gamma-ray Burst Progress • Beppo/SAX finds evidence for X-ray afterglow from several GRBs (2/28/97) • Jan van Paradijs finds optical afterglow • Redshifts indicate cosmological distances (Keck, HST) • ROTSE catches GRB in the act at visible wavelengths (1/23/99) • Evidence mounts for two types of GRBs

  25. What BeppoSAX Saw

  26. What HST Saw (Much Later)

  27. Models for GRBs Hypernova Merging Neutron Stars

  28. INTEGRAL (2002-)

  29. New Missions = Better Data HETE II (launched 10/9/00) INTEGRAL (2002) Swift (2004) GLAST (2008) Swift

  30. Gamma Ray Large Area Space Telescope • Launch in 2008? • 20 MeV to 300 GeV • Wide-field imaging telescope • NASA cost is $326

  31. GLAST design

  32. GLAST Technologies

  33. GLAST All Sky Map

  34. Gamma ray Air shower ~ 10 km ~ 1o Cherenkov light ~ 120 m Detection of TeV gamma rays with Cherenkov telescopes

  35. Camaras

  36. H.E.S.S.

  37. New instruments coming online CANGAROO III H.E.S.S.

  38. MAGIC VERITAS (photomontage)

  39. Detection of TeV gamma rays from the Crab Nebula Whipple 1989: 50 h observation time HEGRA 1997: 15 min HESS 2004: 30 sec Progress

  40. For More Information • Imagine the Universe! -http://imagine.gsfc.nasa.gov/ • Swift Mission - http://swift.sonoma.edu/ • GLAST Mission - http://ww-glast.sonoma.edu/ • CGRO Mission - http://cossc.gsfc.nasa.gov

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