Developments in

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Cassiopeia A viewed by Spitzer Space Telescope,
Hubble Space telescope and Chandra X-ray
observatory
Developments in Very High Energy Gamma Ray
Astronomy
Stephan LeBohec, September 28th 2006
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on board C-GRO, 100 MeV-30GeV gamma-ray sky
map 1991-1998
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Imaging Atmospheric Cherenkov Technique
1TeV
Source
0.5o
100 photons/m2 In 5ns
Difficulty CR discrimination
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O.C.DeJager et al., ApJ, 457253, 1996
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Active Galactic Nuclei
BL-Lac / Blazer jet along line of sight
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VERITAS Collaboration 65 members in more than
20 institutions
Funding from NSF/DOE/Smithsonian/PPARC/SFI/NSERC 2
003 Prototype telescope 2004 Full 4 telescope
project
2007
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VERITAS ELECTRONICS
Watch this space in Fall 2006
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Horseshoe Canyon, Kitt Peak
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T3
T4
T1
T2
T2
VERITAS at the Fred Lawrence Whipple
Observatory Many Thanks to all the U of U
Physics Department undergraduate students for
their hard work in the dry heat!
T1
T3
T4
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VERITAS OPtical Telescope Injection and
Calibration System
with Hakima Manseri
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Rayleigh scattering based Absolute Calibration
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GrISU(tah) simulation and analysis package
20ns/event 6ns frame every 2ns
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First VERITAS Stereoscopic detection Markarian
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Analysis by Michelle Hui
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HESS discoveries in the southern hemisphere
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Terrific prospects for upcoming experiments
and for the northern hemisphere!
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Northern skies supernova remnants

Cassiopea A, 300 years old, type II HEGRA
tentative detection 0.03Crab
Tycho, 430 yeas old, Type Ia HEGRA upper limit
0.03Crab
Also IC443, Gamma-Cygni, . . .
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Cygnus region

9 NSRs, several OB associations, Wolf-Rayet stars
VERITAS scan of the galactic plane Key science
project
But where will we stand from the point of view
of Cosmic Ray accelerators identification?
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Vela Jr SNR 200pc/1000pc 500years
Lepton model B6 mG (!)
ROSAT
Hadron model B120 mG
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The case of RXJ1713 (1kpc, 1000years)
Lepton model
Hadron model
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VELA-X 10000 years old Super-Nova remnant
300pc away a pulsar wind nebula case
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Required exposure
a few 100km2.h
with Pierre Colin
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High Altitude Water Cherenkov
900 photo-multipliers in 22,500m2 water pool
Angular resolution 0.25o
EGRET
GLAST
VERITAS
HAWC
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Atmospheric Cherenkov light different approaches
S gt 1km² Impact gt 550m FOV gt 12º
1km²
130 m
Impact parameter
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TALE Tower
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Fairy Tale Towers gt Survey of north sky gt
Stereo-measurement (500 m spaced TALE-tower )
500m
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G R A T I S 37 telescopes on 1km2 Diameter
5m Field of view 4o Cost 17M
700 hours / year 14 sources 50 hours / source /
year
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Compared sensitivities
One year 5 sigma gt10 events point source
sensitivity
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• Telescope Array Telescope
• Stopped operation in 1997
• 7 are now in storage in Utah
• No camera or electronics
• VERITAS (12m) threshold 100GeV TA ( 3m)
  threshold 400GeV

With Pierre Colin, Gary Finnegan, Micah Kohutek,
Ty Eldridge, Ben Adams David Kieda Thanks to
John Matthews, Mike Cassidy and Gary McDonough
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• Conclusions
• TeV Gamma Ray Astronomy
• VERITAS is finally on track, science data taking
  starts this fall 2006!
• The northern hemisphere is about to be explored
  with MAGIC and VERITAS
• Prospective for the future development of gamma
  ray astronomy is great
• Will HESS/MAGIC/VERITAS unambiguously
• identify cosmic ray accelerators? . . . . . . . .
  . . . . . Probably not!
• How to make progress in that direction?
• Look at higher energies where only hadron
  processes can contribute
• Technology, engineering and support required
  within reach