THE POTENTIAL OF THE GROUND-BASED ARRAYS OF IMAGING ATMOSPHERIC CHERENKOV TELESCOPES .2. GAMMA-RAY FLUX SENSITIVITIES

We discuss the capability of '100 GeV' class imaging atmospheric Chere nkov telescope (IACT) arrays as future powerful instruments of ground- based gamma-ray astronomy. It is assumed that the array is gathered fr om individually triggered quadrangular 4-IACT 'cells' with a linear si ze of about 100 m. The multi-cell concept allows coverage of large det ection areas economically, and at the same time the effective exploita tion of the stereoscopic approach of determination of the shower param eters using information obtained by several IACTs simultaneously. Dete rmination of arrival directions of gamma-ray primaries on an event-by- event basis with accuracy delta theta less than or equal to 0.1 degree s combined with high suppression efficiency (at both the hardware and software levels) of the background hadronic showers by a factor of app roximate to 10(3), and large, up to 1 km(2) collection areas, can prov ide minimum detectable energy fluxes of greater than or equal to 100 G eV gamma-rays from point sources down to 10(-13) erg/cm(2) s which is about 3 orders of magnitude lower than the current sensitivities achie ved by the satellite-borne detectors at MeV and GeV energies. High sen sitivities of multi-IACT arrays would partially compensate the limited efficiency of the technique for all-sky surveys, as well as allow stu dy of moderately extended (less than or equal to 1 degrees) gamma-ray sources. IACT arrays with minimum detectable fluence of greater than o r equal to 100 GeV gamma-rays S-gamma erg/cm(2) are well suited for ef fective exploration of highly sporadic nonthermal phenomena from diffe rent classes of astrophysical objects on time-scales from less than or equal to 1 s to several minutes. (C) 1997 Elsevier Science B.V.