All-sky X-ray and Gamma-ray Astronomy Monitor (AXGAM)

A wide field-of-view, arcsecond imaging, high energy resolution X-ray and low energy gamma ray detector is proposed for a future space mission. It is specifically designed to detect and find counterparts at other wavelengths for γ-ray bursts (GRBs). Detection of GRBs requires wide field-of-view (π to 2π field-of-view) and high sensitivity. This will be achieved by using high quantum efficiency CdZnTe pixel detectors with a low energy threshold (few keV) to observe the larger flux levels at lower energies, and large effective area (625 to 1000 cm) per coded aperture imaging module. Counterpart searches can only be done with ultra-high angular resolution detectors (10 to 30" FWHM) which gives 1 to 5" position determination especially for strong GRBs. A few arcsecond size error box is expected to contain at most one object observed at another wavelength. This will be achieved by using ultra-high spatial resolution pixel detectors (50×50 to 100×100 μm) and a similar resolution coded aperture to achieve the required angular resolution. The low energy range may provide important new information on GRBs and the high energy resolution is expected to help in the observation and identification of emission and absorption lines in the GRB spectrum. The effective energy range is planned to be 2 to 200 keV which is exceptionally wide for such a detector. The major scientific goals of the proposed mission in addition to continuously monitoring GRBs, is to observe AGN, transient phenomena, isolated and binary pulsars, and solar flares. A space-deployed AXGAM detector is expected to observe a few hundred GRBs per year