Gamma-ray Mapping of the Interstellar Medium and Cosmic Rays in the Galactic Plane with GLAST Yasushi Fukazawa 1, T. Kamae 1,2, T. Ohsugi 1, T. Mizuno 1, S. Yoshida 1, K. Hirano 1, M. Ozaki 3, and GLAST team (1:Hiroshima University, 2:SLAC, 3:ISAS) GLAST, the next gamma-ray satellite, will be launched in 2005 under USA, Japan, Italy, France, and so on. New ｔ echnologies, such as silicon-strip detectors developed in Hiroshima University, enable us to obtain a much imporoved capabilities for gamma-ray observations; 50 times as good as sensitivity as EGRET, good source location down to a few arcmins, and a wider field of view with 20% of the whole sky. Thanks to these characteristics, GLAST will detect more than 10,000 objects. Together with Gamma-ray bursts, Pulsars, BLAZARs, SNRs, Dark matters, the mapping of the Galactic diffuse gamma-ray emission is one of key sciences. This enables us to obtain the distribution of the interstellar medium and cosmic rays in the Galactic plane, especially of protons. We are now developing not only FM silicon-strip detectors but also instrumental simulators which will help us to perform such complex analyses.

SAS-2 OSO-3 COS-B EGRET (CGRO) GLAST Increase of number of detected objects GLAST will detect >10,000 gamma-ray sources. Various kinds of astronomical objects can be observed, and thus GLAST will open a new era of gamma-ray astronomy. EGRETGLAST 1

9cm Silicon-Strip Detector (FM) Developed by Hiroshima Univ. and HPK (Japan) New Technology PD readout Anti-Coincidence Detector （ＡＣ Ｄ） CsI-Array Calorimeter （ＣＡＬ） Plastic-Scinti + PMT 4x4 array of identical towers Si -Pb Tracker （ＴＫ Ｒ） 2

EGRET GLAST Energy Band 30MeV--10GeV 20MeV--100GeV Field of View 0.5sr 2.4sr (20% of 4π) Effective Area 1,500cm2 11,000cm2 Energy Resolution 10% 10% Dead time per 1 event 100ms 20μs Source Location 5--30arcmin arcmin Sensitivity ～ 1×10 -7 cm -2 s -1 ～ 1×10 -7 cm -2 s -1 (1day) ～ 2×10 -9 cm -2 s -1 (2years) Number of Detected objects 271 >10000 Weight 1820kg 2560kg Orbit(28.5 O incl.) 350km 550km Life time 9years >5yesrs Basic Performance of GLAST EGRET GLAST 3

GLAST is also important as All-sky Monitor 1orbit １ day １００ sec Wide field of view （ 20% of the whole sky ） can cover 85% of the whole sky in 1orbit (100min) 200 Gamma-ray Bursts per year Day-scale light curve will be available for all 3EG sources + 80 new sources 10 4 sources in 2 years GLAST and MAXI (Japanese X-ray all-sky monitor, 2005-) cooperation will be important. Sky covering 4

Pi-0 decay (cosmic ray p) * (interstellar gas) IC (cosmic ray e) * (interstellar photon) Radio-synchrotron (cosmic ray e) * (interstellar B) 100MeV100GeV Bremss(e) π decay(p) Inverse Compton (e) One of key sciences of GLAST is the Diffuse Gamma-Ray Emission along the Galactic Plane. We can study energy density and distribution of Cosmic-ray Proton, Electron, and Gas (and B), separately, and study the Galactic Structure and Formation in terms of Energetics ! Bremss (cosmic ray e) * (interstellar gas) 0 COS-B (Mayer-Hasselwander et al. 1982) Gamma-ray is emitted by the interaction between the interstellar medium and cosmic-rays. 5

Koyama et al Tanimori et al EGRET image (left) and GLAST Simulation of the Gamma-Cyg where supernova remnant and molecular cloud are thought to be interacting. Evidences of particle acceleraton in the supernova remnant SN1006. Identify the cosmic-ray acceleration sites. Pulsar nubula From top, 408MHz （ Synchrotron ）、 21cm(H1) 、 CO(H 2 ) 、 FIR （ dust,HI ）、 NIR ・ optical(stars) 、 Ｘ -ray （ hot gas ） Multi-wavelength images of the Galactic plane 6

LMC (EGRET detected) Starburst Galacy: Ｍ８２ Clusters of galaxies Simulated gamma-ray spectrum of the Galactic plane with GLAST Orion ＥＧＲＥＴ image of the giant molecular cloud ＳＭＣ Digel et al Non-biasing survey of the interstellar gas and cosmic-ray protons and electrons! GLAST simulation M31 Comparison of cosmic-ray density with other galaxies Combined with other wavelength data, we can obtain the distribition of various Galactic materials. Galaxy radiation simulator (2x2degre 2 ) 7 Extended emission Complex Detector Responses Scanning observation But, Forward method anlysis with full-detecor and BGD simulator is valuable and efficient.

We are now developing ….. Protons Electrons Detector simulator (Geant4) Cosmic-ray generator for BGD simulation These are at first applied to the Balloon flight experiments (see postar p210). Further works... Extention to FM model, include He, e+, gamma-ray etc. Tuning through calibrations, study of BGD rejection 8