1. 2 - 13 July 2004, Erice1 The performance of MAGIC Telescope for observation of Gamma Ray Bursts Satoko Mizobuchi for MAGIC collaboration Max-Planck-Institute for physics (Werner-Heisenberg-Institute) Muenchen

2. 2 - 13 July 2004, Erice2 Low Energy Threshold GRBs originate in cosmological distances High energy γ-rays are absorbed through the interaction with infrared photon Energy cutoff is expected from 50GeV to 100GeV Need a detector with low energy threshold!! MAGIC Effective collection area 10 3 m 2 ～ 10 5 m 2 (10GeV-100GeV) Need a fast slewing telescope GRB Duration time: few seconds - several minutes SWIFT : 5 arc-minutes accuracy within 10 seconds Fast slewing time MAGIC Slewing time < 20s Gamma-Ray Bursts detection by MAGIC 40GeV 10GeV

3. 2 - 13 July 2004, Erice3 The MAGIC sensitivity and expected prompt GRB spectra 10 -10 10 -11 MAGIC 10 -6 10 -7 10 -8 10 -9 Ref : Prompt GRB spectra : detailed calculations and the effect of pair production Asaf Pe’er and Eli Waxman astro-ph/0311252 11 Nov 2003 Condition L = 10 52 erg ε e = ε B = 10 -0.5, p=3 ∆t = 10 -2 s, Γ= 300 (l´ = 2.5) ∆t = 10 -3 s, Γ= 600 (l´ = 0.8) ∆t = 10 -4 s, Γ= 1000 (l´ = 0.6) Assumption Luminosity distance d L = (1+Z) r = 2×10 28 z = 1 10s 100s

4. 2 - 13 July 2004, Erice4 E peak α β Energy Flux BATSE GRB Current Catalog (2702 GRBs) - fluence - duration - light curve (64ms resolution) The spectral catalog (95 bursts) - amplitude(A), low-energy spectral index (α), high-energy spectral index (β), peak energy (E peak ) Ref : http://www.batse.msfc.nasa.gov/batse/grb/catalog/current/, http://cossc.gsfc.nasa.gov/batse/batseburst/sixtyfour_ms/,http://www.batse.msfc.nasa.gov/batse/grb/catalog/current/http://cossc.gsfc.nasa.gov/batse/batseburst/sixtyfour_ms/ Preece R.D., ApJ 496: 849- 862, April 1998, Preece R.D., ApJ Supp., 126, 19-36, Jan 2000 E peak β Information of GRBs detected by BATSE

5. 2 - 13 July 2004, Erice5 300keV α β Energy Flux Normalize T90 Fluence Expected spectrum of GRBs

6. 2 - 13 July 2004, Erice6 MAGIC (PMT) Index -2.2 10GeV – 20GeV 10.7σ 20GeV – 40GeV 16.3σ BG 40Hz MAGIC observation time BG 20Hz Observation Start time Significance > 5 σ Observation start time 15sec – 30sec 10GeV- 20Ge V 20GeV- 40Ge V -2.52.0%3.0% -2.224%29% -1.941%42% Detection capability with MAGIC Telescope BATSE

7. 2 - 13 July 2004, Erice7 With HPD Advanced Camera Larger observable sky x1.7 Higher Detection efficiency x1.3 Predicted number of GRBs by SWIFT Satellite : ～ 200 bursts/year Duty Cycle of observation time by MAGIC14% Observable sky by MAGIC 15% (zenith angle <45˚) GRB detection efficiency by MAGIC: >24% ≥1.0 bursts/year Number of observable GRBs with MAGIC Preliminary

8. 2 - 13 July 2004, Erice8 Thank you

9. 2 - 13 July 2004, Erice9 1.BATSE GRB Current Catalogue (2702 bursts) -Fluence -Duration time -Light curve (Time Profile) 2. Assume Power law index -1.9,-2.2 and -2.5 between 300keV and 40GeV energy, estimate Gamma Ray flux at 10-20 GeV, 20-40 GeV energy bins. 3.Convolute MAGIC acceptance with Gamma Ray flux at 10-20GeV, and 20-40GeV 4.Add Expected Hadron shower rates 40Hz, and 80Hz in 10-20GeV and 20-40GeV energy bin. Estimation of gamma-ray rate at MAGIC energy Gamma Ray flux at 300keV Toy Simulation

10. 2 - 13 July 2004, Erice10 MAGIC HETE2( 2000- ) SWIFT (2004.09- ) XMM (1999-) ASTRO-E Ⅱ (2005.02-) ASCA (1993-2000) ROSAT( 1990-1999 ) RXTE( 1995- ) BeppoSAX( 1996-2002 ) Chandra( 1999- ) CGRO ( 1991-2000 ) GLAST( 2007.02- ) INTEGRAL( 2002- ) MAGIC The energy range INTEGRAL HETE2 SWIFT

11. 2 - 13 July 2004, Erice11 Shock plasma conditions (6 free parameters) 1.Related to the underlying source Total luminosity L [erg] Lorentz factor of the shock plasma Γ Variability time ∆t [s] ( assumption : thickness of shells is c ∆t ) 2.Related to the microphysics Ratio of the magnetic field energy density to the total thermal energy The fraction of the total thermal energy E which goes into random motions of the electrons Power law index d log n e / d log εe = -p Comoving compactness ∆R : comoving width :comoving number photon density : Thomson cross section Plasma parameters

12. 2 - 13 July 2004, Erice12 Relevant physical processes 1.Synchrotron emission 2.Synchrotron self absorption 3.Compton scattering (eγ → eγ) 4.Inverse Compton 5.Pair production (e + e - → γγ) 6.Annihilation (γγ → e+e - ) : magnetic field U int : internal energy density Time dependent numerical model