EXIST: A High Sensitivity Hard X-ray Imaging Sky Survey Mission for ISS
J. Grindlay
L. Bildsten
D. Chakrabarty
A. Fabian
F. Fiore
M. Elvis
N. Gehrels
F. Harrison
D. Hartmann
T. Prince
R. Rothschild
S. Woosley
Abstract
An imaging survey of the hard x-ray ( ~ 5-600 keV) sky has never been conducted
despite the enormous potential of this frontier band linking the predominantly
thermal (x-ray) and non-thermal (gamma-ray) universe. The 1994 New Mission
Concept (NMC) studies selected by NASA included the Energetic X-ray Imaging
Survey Telescope (EXIST), which was studied for both an intermediate-class
free flyer mission and a MIDEX implementation. The scientific requirements
for a deep hard x-ray (HX) survey mission have now increased so that a larger
telescope and instrument complement is needed to accomplish updated scientific
objectives. EXIST is now envisioned as an array of 8 telescopes, each with
imaging detector (CZT) area of ~ 1m2, as the readout of a coded aperture
telescope
with 40 deg (FWHM) field of view, and mutually offset for a combined total
survey
field of view (FOV) 40deg x 160deg. This large total payload ( ~ 3000kg), with
its
fixed local-zenith pointing, is then an ideal candidate for an attached
payload on ISS.
With the long axis of the combined FOV aligned perpendicular to the orbital
vector
and the offset fields thus aligned along the main Truss, the telescope
completes an
all-sky image each orbit and over ~ 1 year can achieve a sensitivity of
0.05mCrab
(10-100 keV; ~ 0.5mCrab, 100-500 keV), or nearly 1000X better than the only
previous
(non-imaging) HX survey, HEAO-A4 (1979). A 2-3 year mission would enable the
sky
to be imaged and catalogued for variability on time scales from microseconds
to
months, and would make possible fundamental studies of active galaxies,
quasars, and
obscured AGN; gamma-ray bursts in distant galaxies and SGRs in local galaxies;
accreting black holes and compact objects in our Galaxy; and hidden supernova
remnants
in the Galaxy. An overview of the science goals and mission concept will be
presented.
File translated from TEX by TTH, version 2.32.
On 11 Sep 1999, 08:39.