Subject: GeV Gamma-ray Data
Question:
Please, can you be so kind to give me some informations. I've read this sentence written on the proceedings of a school I've attended:
"direct detection for HE (30 MeV-30 GeV) and ground based Cerenkov for VHE (up to 30 TeV). Up to now, there is no frontier contests as there exists an unexplored region extending over a about a decade on both sides, from 3 to 30 GeV and from 30 to 300 GeV, with essentially no data."
What does it mean that in the band 3-30 GeV there is no data?
Maybe the Egret data in 3-30 GeV are few...?
Answer:
Indeed, EGRET detected about 2000 gammas with E>10 GeV (see, e.g., Dingus and Bertsch in the Gamma2001 proceedings, p251). From a given source, however, the number of photons is very small so that as a practical matter it is not possible to get detailed spectra in the gap. The next generation of ground-based and space-based instruments will, together, close the gap on at least a few sources.
Dr. Steven Ritz, NASA-GSFC
GLAST Deputy Project Scientist and LAT Instrument Scientist