The EXIST mission has been recently re-designed prior to being proposed to the ASTRO2010 Decadal Survey. One of
the most recent improvements has been the addition of a third instrument consisting of a powerful Soft X-ray Imager
(SXI) that will study in detail and help characterizing the high energy sources detected by the High Energy Telescope
(HET). The EXIST concept fully exploits the heritage of Swift in the fast follow-up of transients and in particular GRBs,
with 10 to 20 times more sensitivity in the high energy band (from 0.2 to 600 keV) and exceptional performance in the
near-IR/optical provided by the Infrared Telescope (IRT). SXI has an important role in extending by more than one
decade in energy, down to the soft X-rays the coverage of HET. Such combination will be fully exploited when
performing pointed observations. Within the EXIST follow-up program, foreseen during the second part of the mission,
SXI and HET will be able to collect high quality spectra for thousands of sources covering the energy range 0.1-
hundreds keV. Furthermore, while working in survey mode SXI will cover about half the sky in 2 years and will be able
to improve the location accuracy of many faint HET sources (reducing the positional uncertainty from 20 arcsec to ~ 1-2
arcsec). In this paper we will address the performance and the main scientific contributions expected from SXI.
The Energetic X-ray Imaging Survey Telescope (EXIST) will continuously survey the full sky in scanning mode for 2-
years followed by a 3-years pointing phase. The mission includes three instruments: a High Energy coded mask
Telescope; a 1.1m aperture optical-IR Telescope; and a Soft X-ray Imager (SXI), sensitive in the 0.1-10 keV band. SXI
is proposed as a contribution of ASI-Italy, fully developed by Italian institutes. Here we will present the optical and
mechanical design of the SXI mirror module, that includes also a pre-collimator and a magnetic diverter to ensure a low
background on the detector. In particular we will describe the mirror module characteristics in term of effective area,
imaging capability, thermal requirement and mechanical properties. The current optical design foresees 26 shells
providing an effective area comparable to one XMM-Newton mirror module up to 3 keV. The realization of these shells
is based on the well-proven Nickel replication-process technology.
The Energetic X-ray Imaging Survey Telescope (EXIST) mission, submitted to the Decadal Survey, is a
multiwavelength observatory mainly devoted to the study of Super Massive Black Holes, Gamma Ray Bursts and other
transient sources. The set of instruments foreseen for EXIST includes a soft x-ray telescope (SXI), proposed as a
contribution of the Italian Space Agency (ASI).
We present the baseline design of the X-Ray camera for SXI telescope, that we have finalized under ASI contract. The
camera is based on a focal plane detector consisting of a 450 μm thick silicon pixel sensor sensitive, with high QE, in the
full SXI range (0.1-10 KeV), and capable of high energy resolution when operated in photon counting mode (E/dE ~ 47
at 6 keV), frame rate ~ 100-200 frames/s (enabling timing in the ms range), and spatial resolution matching the optical
characteristics of the mirror module. We provide an overview of the mechanical, thermal and electrical concept of the
The EXIST observatory planned for launch in the next decade will carry outstanding contributions in both Galactic and
Extragalactic science with a sensitivity about 10-20 better respect to the flown hard X-ray missions and full sky survey
capability. Designed mainly for the survey of SMBH and transients, thanks to the wide field of view (~70x90deg) and
large effective area of the High Energy Telescope (HET), the study of spectra and variability at all timescales of all types
of Galactic sources will be made possible. EXIST will be also capable to study in detail the Galactic Center (GC) in the
hard X-rays. This crowded region as observed recently by Chandra, Integral and Swift has been found to possibly host a
high number of high energy sources. In this work we report on the capabilities of EXIST to image the GC region and to
detect and characterize the different classes of sources on the basis of their known spectral and variability properties.
EXIST will perform the crucial observation tests to study the emission from Sgr A*, using the simultaneous observations
of IR and X-ray flares, searching for periodicity to study the Keplerian flow with NIR and/or X QPO, confirm or not the
high energy counterpart of SgrA* detected by INTEGRAL and define the spectral shape of the high energy tail. Finally,
EXIST can effectively and continuously monitor spectra from Sgr B2 to confirm the correlation of the iron line emission
with the hard X-ray continuum and establish its origin.
The Energetic X-ray Imaging Survey Telescope (EXIST) is a mission that has been studied for the NASA Physics of the
Cosmos Program. EXIST will continuously survey the full sky by scanning for 2-years (with 2-3 interruptions per day
for GRB follow-up) followed by a 3-years pointing phase. The mission includes three instruments: a High Energy coded
mask Telescope; a 1.1m aperture optical-IR Telescope; and a Soft X-ray Imager (SXI), sensitive in the 0.1-10 keV band.
SXI is proposed as a contribution of ASI-Italy, fully developed by Italian institutes. The current optical design foresees
26 shells providing an effective area comparable to one XMM-Newton mirror module up to 3 keV and somewhat lower
from 3 to 10 keV. The realization of these shells is based on the well-proven Nichel replication-process technology. Here
we will present the optical design of the SXI mirror module and describe its characteristics in term of effective area and
imaging capability, summarizing also the characteristics of the full SXI telescope.
The SXI telescope is one of the three instruments on board EXIST, a multiwavelenght observatory in charge of
performing a global survey of the sky in hard X-rays searching for Supermassive Black Holes. One of the primary
objectives of EXIST is also to study with unprecedented sensitivity the most unknown high energy sources in
the Universe, like high redshift GRBs, which will be pointed promptly by the Spacecraft by autonomous trigger
based on hard X-ray localization on board. The recent addition of a soft X-ray telescope to the EXIST payload
complement, with an effective area of 950 cm2 in the energy band 0.2-3 keV and extended response up to 10 keV
will allow to make broadband studies from 0.1 to 600 keV. In particular, investigations of the spectra components
and states of AGNs and monitoring of variability of sources, study of the prompt and afterglow emission of GRBs
since the early phases, which will help to constrain the emission models and finally, help the identification of
sources in the EXIST hard X-ray survey and the characterization of the transient events detected. SXI will also
perform surveys: a scanning survey with sky coverage ~ 2 π and limiting flux of ~ 5 × 10-14 cgs plus other
serendipitous. We give an overview of the SXI scientific performance and also describe the status of its design
emphasizing how it has been derived by the scientific requirements.
The Gamma-Ray Imager (GRI) is a novel mission concept that will provide an unprecedented sensitivity leap in the soft gamma-ray domain by using for the first time a focusing lens built of Laue diffracting crystals. The lens will cover an energy band from 200 - 1300 keV with an effective
area reaching 600 cm2. It will be complemented by a single reflection multilayer coated mirror, extending the GRI energy band into the hard X-ray regime, down to ~10 keV. The concentrated photons will be collected by a position sensitive
pixelised CZT stack detector. We estimate continuum sensitivities of better than 10-7 ph cm-2s-1keV-1 for a 100 ks exposure; the narrow line sensitivity will be better than 3 x 10-6 ph cm-2s-1 for the same integration time. As focusing instrument, GRI will have an angular resolution of better than 30 arcsec within a field of view of roughly 5 arcmin - an unprecedented achievement in the gamma-ray domain. Owing to the large focal length of 100 m of the lens and the mirror, the optics and detector will be placed on two separate spacecrafts flying in formation in a high elliptical orbit. R&D work to enable the lens focusing technology and to develop the required focal plane detector is currently underway, financed by ASI, CNES, ESA, and the Spanish Ministery of Education and Science. The GRI mission is proposed as class M mission for ESA's Cosmic Vision 2015-2025 program. GRI will allow studies of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.
We present a mission designed to address two main themes of the ESA Cosmic Vision Programme: the Evolution of the Universe and its Violent phenomena. ESTREMO/WFXRT is based on innovative instrumental and observational approaches, out of the mainstream of observatories of progressively increasing area, i.e.: Observing with fast reaction transient sources, like GRB, at their brightest levels, thus allowing high resolution spectroscopy. Observing and surveying through a X-ray telescope with a wide field of view and with high sensitivity extended sources, like cluster and Warm Hot Intragalactic Medium (WHIM). ESTREMO/WFXRT will rely on two cosmological probes: GRB and large scale X-ray structures. This will allow measurements of the dark energy, of the missing baryon mass in the local universe, thought to be mostly residing in outskirts of clusters and in hot filaments (WHIM) accreting onto dark matter structures, the detection of first objects in the dark Universe, the history of metal formation. The key asset of ESTREMO/WFXRT with regard to the study of Violent Universe is the capability to observe the most extreme objects of the Universe during their bursting phases. The large flux achieved in this phase allows unprecedented measurements with high resolution spectroscopy. The mission is based on a wide field X-ray/hard X-ray monitor, covering >1/4 of the sky, to localize transients; fast (min) autonomous follow-up with X-ray telescope (2000 cm2) equipped with high resolution spectroscopy transition edge (TES) microcalorimeters (2eV resolution below 2 keV) and with a wide field (1°) for imaging with 10" resolution (CCD) extended faint structures and for cluster surveys. A low background is achieved by a 600 km equatorial orbit. The performances of the mission on GRB and their use as cosmological beacons are presented and discussed.
The mission concept MAX is a space borne crystal diffraction telescope, featuring a broad-band Laue lens optimized for the observation of compact sources in two wide energy bands of high astrophysical relevance. For the first time in this domain, gamma-rays will be focused from the large collecting area of a crystal diffraction lens onto a very small detector volume. As a consequence, the background noise is extremely low, making possible unprecedented sensitivities. The primary scientific objective of MAX is the study of type Ia supernovae by measuring intensities, shifts and shapes of their nuclear gamma-ray lines. When finally understood and calibrated, these profoundly radioactive events will be crucial in measuring the size, shape, and age of the Universe. Observing the radioactivities from a substantial sample of supernovae and novae will significantly improve our understanding of explosive nucleosynthesis. Moreover, the sensitive gamma-ray line spectroscopy performed with MAX is expected to clarify the nature of galactic microquasars (e+e- annihilation radiation from the jets), neutrons stars and pulsars, X-ray Binaries, AGN, solar flares and, last but not least, gamma-ray afterglow from gamma-burst counterparts.
The MART-LIME is a large area x-ray experiment planned to be launched on board the Russian satellite Spectrum X-Gamma, as the high energy imager of a complement of broad band co- aligned x-ray telescopes. The energy range covered is 5 - 150 keV with an angular resolution of 8.6 arcminutes. The final detector configuration is now in its testing phase and includes the high pressure window comprising the 6 by 6 degree collimator, and the multiwire proportional counter (MWPC). The response to x-ray sources was investigated during the tests carried out at the Daresbury Laboratory (Warrington, UK) facilities The MWPC was filled up by a xenon-argon-isobutane gas mixture in order to evaluate the efficiency of the detector and in particular its linearity over the whole approximately 2,000 cm2 sensitive area. At the same time the various parts of the apparatus have been simulated by using a Monte Carlo program. Results on the detector response and simulations are presented.
To follow up on the remarkable discoveries of the Compton Gamma Ray Observatory and GRANAT, the International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission was selected by ESA as part of the agency's 'HORIZON 2000' strategic plan. It is scheduled to begin detailed gamma ray spectral and imaging studies, of unprecedented resolution, in the year 2001. One of the two main INTEGRAL instruments is a high performance imager. It features a coded aperture mask and a novel large area multilayer detector which utilizes both cadmium telluride and cesium iodide elements to deliver the fine angular-resolution approximately 12 arcmin, wide spectral response (15 keV to 10 MeV) and high resolution spectroscopy (6% at 100 keV) required to satisfy the mission's imaging objectives.
IAS, a CNR institute for space research in Astrophysics, in collaboration with IKI on their invitation, has developed, and is now under building, an X-Ray Imaging and Spectroscopic telescope as the high energy instrument on board the Observatory Spectrum X-Gamma. The scientific aim of this instrument, named MART-LIME, will be the detailed study of X-Ray sources emitting in the energy range 5 - 150 keV. The MART-LIME telescope is a follow up in a series of X-Ray detectors that have been developed, built at IAS and flown on board stratospheric balloons. It consists of a high pressure gas operated multiwire proportional counter with bidimensional spectral resolution coupled with a coded mask placed at 2.3 meter.
Recent results obtained by balloon and satellite borne coded-mask instruments have been used to simulate the imaging performance of MART-LIME, a coded mask telescope to be flown on board the international observatory SPECTRUM-X-GAMMA on 1995. In particular, we discuss a 6x6 square degree field-of-view centered on the hard X-Ray source responsible for the high energy emission from Galactic Center, at energies above 30 keV. The contributions of GX1+4, GRS1758-25, Terzan 2, Tr 1741-322 and GX354-0 to this field-of-view are also considered. Deconvolved images obtained via the cross-correlation technique are presented. From these images, the limiting sensitivity of the telescope in a crowded sky field is correctly determined.
MART-LIME is a coded mask imaging telescope to be flown onboard the international observatory SPECTRUM X-(Gamma) in 1995. This high-energy instrument, the center of which is a high-pressure proportional counter sensitive to the 5 - 150 keV energy range, will be characterized by a limiting sensitivity of about 1 milliCrab for a 105 s observation period. The imaging capability of the instrument is provided by a coded-mask aperture system, used in conjunction with a position sensitive detector. The basic pattern of the coded aperture is a 71 X 73 URA mask (twin prime). With the addition of an outer frame comprising 18 pixels on each side, a fully coded field-of-view of 2.6 degree(s) X 2.6 degree(s) is obtained, while a partially coded field-of-view is achieved up to 6 degree(s). Test procedures used to determine the performance of the MART-LIME detector are discussed. Results showing the spectroscopic capabilities of a Laboratory-Prototype detector are presented.
The concept, operational principle, and test results are presented for a new type of high-pressure high-spatial resolution proportional counter with enhanced spectroscopic capability. The detector in its baseline configuration is to be filled with a xenon/quench gas mixture at 5 bar and is to be sensitive over the 5-150 eV energy range. The position resolution will range from 0.5 mm at the lower energies to around 1 mm at the upper end of the energy range. The very high timing resolution of this new detector allows high count rate capacity and enables the application of the escape gating technique to achieve a high spectral resolution at energies above the xenon K edge.
Consideration is given to a new type of position-sensitive MultiWire Proportional Counter proposed as the high-energy instrument for the Spectrum X-Gamma Satellite. Two of them are based on high-throughput X-ray optics, sensitive up to about 20 keV. The third one, MART-LIME, is the high-energy instrument to cover the band 5-150 keV. This X-ray observatory-class orbiter comprises three major coaligned instruments. The scientific objective of this hard X-ray telescope is to produce sky images with arcmin angular resolution and good spectral resolution and submilliCrab sensitivity, during a typical observation time of 100,000 sec. The MART-LIME experiment is expected to produce a breakthrough in high-energy astrophysics by means of deep observations over a wide field of view. The missions are to produce a complete hard X-ray catalog, which is still nonexistent at the milliCrab sensitivity level.