Gamma-Ray Burst Studies with the Energetic X-ray Imaging Survey Telescope (EXIST)

The Energetic X-ray Imaging Survey Telescope (EXIST) is a sensitive, wide field of view hard X-ray (10–600 keV) coded-aperture telescope. This paper describes the capabilities and characteristics of EXIST as proposed to NASA’s Medium—Class Explorer (MIDEX) program. A larger version of EXIST is being studied as a NASA New Mission Concept. In addition to its primary science objective, which is to carry out the first high-sensitivity (0.5 mCrab) hard X-ray imaging survey (14’ resolution) of the entire sky, EXIST has a number of important Gamma-Ray burst (GRB) objectives which include: 1) A sensitive observation toward M31 to search for an extended burst halo to confirm or eliminate models in which isotropically emitting burst sources are distributed in an extended (∼200–400 kpc) Galactic halo. 2) Sensitive wide FOV monitoring to probe the GRB long N -log P distribution an order of magnitude fainter than BATSE 3) Rapid dissemination of accurate (30′′) burst positions for ground-based followup. 4) High time-resolution (100 μsec) burst observations. 5) High quality (ΔE=4.4 keV FWHM @ 60 keV) measurements of GRB spectra