1. CTA The next generation ultimate gamma ray observatory M. Teshima Max-Planck-Institute for Physics

2. CTA SNRs Cold Dark Matter GRBs Cosmological  -Ray Horizon Cosmological  -Ray Horizon Physics Objectives Physics Objectives Origin of Cosmic Rays Quantum Gravity Pulsars AGNs AGNs

3. CTA Galactic Sources HESS Galactic plane Survey Survey in 2-3% Crab unit Astro-ph/0510397 17 sources + Several PWNs Shell type SNRs X-Ray Binary Un-ID sources

4. CTA Extragalactic sources PKS2005PG1553 New Sources Spectral Indices of new sources range 3~4

5. CTA PG 1553 (z>0.25) Very Soft energy spectrum the attenuation by pair creation X-Ray Intensity =6.5μJy Mrk421 9.9 μ Jy Mrk501 9.4 μJy

6. CTA Absorption of gamma rays in the universe Pair Creation; γ ＋ γ  e + + e -

7. CTA The SSC framework Fossati et al. 1998 Higher Z  Higher source luminosity  Lower IC peak  softer spectrum X-ray intensity at 1keV PG 1553 6.5 μJy z~0.3 Mrk421 9.9 μJy z=0.03 Mrk501 9.4 μJy z=0.03 PG1553’s source luminosity ~100 x Mrk 20051553 2344

8. CTA From HESS & MAGIC to CTA About 30 sources are now identified as VHE gamma sources. GLAST will see ~3000 of GeV sources around 2010 GLAST will see ~3000 of GeV sources around 2010 Our target in VHE Energy Our target in VHE Energy ~100 VHE sources in 2010 by HESS-II and MAGIC-II ~1000 VHE sources in 2020 by CTA CTA Sensitivity must be 10 times better than HESS, and MAGIC CTA Sensitivity must be 10 times better than HESS, and MAGIC Importance of all sky observatory  full sky survey  relatively large FOV is favored Extend HESS galactic plane survey to entire sky Extend HESS galactic plane survey to entire sky

9. CTA By W.Hofmann ∝ N tel ∝ Area 50hrs Background LimitedSignal Limited

10. CTA Kifune’s Plot (my optimistic expectation) ~3000 sources by GLAST, AGILE ~1000 sources by CTA GLAST AGILE

11. CTA VHE Log(S)-Log(N) plot HESS-I ~30 sources MAGIC-I ~20 sources Log(N) ~ -1.0 Log(S) ??? HESS-II ~60 sources MAGIC-II ~40 sources CTA South ~300 sources CTA North ~200 sources HESS-II MAGIC-II CTA

12. Picture: Courtesy of W.Hofmann Option: Mix of telescope types ~10 central huge telescopes ~100 small telescopes outside

13. CTA Strategy in Low Energy ~10GeV Eth Image quality is limited by the number of photons and air shower fluctuations Increase photo-collection efficiency Increase telescope density (gain x 4) Increase telescope density (gain x 4) ~100m spacing  ~50m spacing Many sampling points  reduce shower fluctuation effect Increase telescope diameter (gain x 3) Increase telescope diameter (gain x 3) 12m-17m φ  20-30m φ Increase Q.E. of photo-detectors (gain x 3) Increase Q.E. of photo-detectors (gain x 3) Q.E. 20%  60-80% Timing between telescopes may help  S. Biller Timing between telescopes may help  S. Biller Total gain 30~40 in photo collection efficiency could be realistic 10GeV threshold energy with reasonable sensitivity 10GeV threshold energy with reasonable sensitivity Photon sampling rate: HESS, MAGIC ~ 1/1000 Photon sampling rate in CTA should be ~1/30 (10% mirror area, 50% Q.E.) Significant improvement in data quality  intensive M.C. is necessary

14. CTA Strategy in High energy up to 100TeV Extension of the sensitivity up to 100TeV to study galactic cosmic ray source  CTA south only Current IACTs’ sensitivity is just limited by the number of gamma events Emax ~10TeV  Emax ~100TeV Emax ~10TeV  Emax ~100TeV ~10 5 m 2 (300m x 300m)  ~10 7 m 2 (3km x 3km) ~10 5 m 2 (300m x 300m)  ~10 7 m 2 (3km x 3km)

15. CTA Multi-Messengers observation All sky observatory (N,S stations) Gamma Rays Neutrinos Gamma Ray & X-Ray Satellites IceCube: 2010 Completion of the construction CTA North CTA South

16. CTA HESS-II and MAGIC-II can be good R&Ds for CTA HESS-II 28m diameter telescope Lower threshold energy In 2008 MAGIC-II 2x17m, High Q.E. detectors Lower threshold energy High Precision In 2007 March 2006

17. CTASummary We definitely need CTA for the development of VHE astrophysics after HESS-II and MAGIC-II 500~1000 sources will be observed in 10-20 years operation  10- 20 hrs/source (time limited) CTA could be an ultimate ground based gamma ray observatory and we should consider north & south stations (All sky observatory) The number of galactic sources may be limited The number of galactic sources may be limited Multi-wavelength and multi-messenger observation are very important to understand the nature of high energy sources New advanced photon detector development will have a strong impact in the design of CTA (HPD, SiPM)