Wednesday 11^th November 2009 - 9:00 A.M.

Università "La Sapienza" Roma 

Title: The Physics of Vacuum Polarization: from GeV to Tev scale 

Thursday 19^th November 2009 - 11:30 A.M.

Università "La Sapienza" Roma - Sala Direzione INFN (Physics Dept., Old Building - 2nd floor)

Title: High energy emission from GRBs, what can we learn from LAT results

Abstract: In this talk I will review the results obtained studying the recent data from the Gamma Ray Monitor (GBM) and LAT. We compare the luminosity function and rate inferred from the GBM long bursts peak flux distribution with those inferred from the Swift and BATSE peak flux distribution. We find that the GBM, BATSE and the Swift peak fluxes can be fitted by the same luminosity function implying the consistency of these three samples. Using the trigger algorithm of the LAT instrument we derive important information on the flux at 100 MeV compared to lower energy detected by the GBM. We find that the simple extension of the synchrotron emission to high energy cannot justify the low rate of GRBs detected by LAT and for several GRBs detected by the GBM, the flux at >100 MeV should be suppressed. Two bursts, GRB090217 and GRB 090202b, detected by LAT have very soft spectra in the GBM and therefore their high energy emission cannot be due to an extension of the synchrotron.