No Arabic abstract
Gamma-ray astronomy presents an extraordinary scientific potential for the study of the most powerful sources and the most violent events in the Universe. In order to take full advantage of this potential, the next generation of instrumentation for this domain will have to achieve an improvement in sensitivity over present technologies of at least an order of magnitude. The DUAL mission concept takes up this challenge in two complementary ways: a very long observation of the entire sky, combined with a large collection area for simultaneous observations of Type Ia SNe. While the Wide-Field Compton Telescope (WCT) accumulates data from the full gamma-ray sky (0.1-10 MeV) over the entire mission lifetime, the Laue-Lens Telescope (LLT) focuses on 56Co emission from SNe Ia (0.8-0.9 MeV), collecting gamma-rays from its large area crystal lens onto the WCT. Two separated spacecraft flying in formation will maintain the DUAL payloads at the lens focal distance.
We briefly present the science capabilities, the instruments, the operations, and the expected performance of the SVOM mission. SVOM (Space-based multiband astronomical Variable Objects Monitor) is a Chinese-French space mission dedicated to the study of Gamma-Ray Bursts (GRBs) in the next decade. The SVOM mission encompasses a satellite carrying four instruments to detect and localize the prompt GRB emission and measure the evolution of the afterglow in the visible band and in X-rays, a VHF communication system enabling the fast transmission of SVOM alerts to the ground, and a ground segment including a wide angle camera and two follow-up telescopes. The pointing strategy of the satellite has been optimized to favor the detection of GRBs located in the night hemisphere. This strategy enables the study of the optical emission in the first minutes after the GRB with robotic observatories and the early spectroscopy of the optical afterglow with large telescopes to measure the redshifts. The study of GRBs in the next decade will benefit from a number of large facilities in all wavelengths that will contribute to increase the scientific return of the mission. Finally, SVOM will operate in the era of the next generation of gravitational wave detectors, greatly contributing to searches for the electromagnetic counterparts of gravitational wave triggers at Xray and gamma-ray energies.
The e-ASTROGAM is a gamma-ray space mission to be proposed as the M5 Medium-size mission of the European Space Agency. It is dedicated to the observation of the Universe with unprecedented sensitivity in the energy range 0.2 - 100 MeV, extending up to GeV energies, together with a groundbreaking polarization capability. It is designed to substantially improve the COMPTEL and Fermi sensitivities in the MeV-GeV energy range and to open new windows of opportunity for astrophysical and fundamental physics space research. e-ASTROGAM will operate as an open astronomical observatory, with a core science focused on (1) the activity from extreme particle accelerators, including gamma-ray bursts and active galactic nuclei and the link of jet astrophysics to the new astronomy of gravitational waves, neutrinos, ultra-high energy cosmic rays, (2) the high-energy mysteries of the Galactic center and inner Galaxy, including the activity of the supermassive black hole, the Fermi Bubbles, the origin of the Galactic positrons, and the search for dark matter signatures in a new energy window; (3) nucleosynthesis and chemical evolution, including the life cycle of elements produced by supernovae in the Milky Way and the Local Group of galaxies. e-ASTROGAM will be ideal for the study of high-energy sources in general, including pulsars and pulsar wind nebulae, accreting neutron stars and black holes, novae, supernova remnants, and magnetars. And it will also provide important contributions to solar and terrestrial physics. The e-ASTROGAM telescope is optimized for the simultaneous detection of Compton and pair-producing gamma-ray events over a large spectral band. It is based on a very high technology readiness level for all subsystems and includes many innovative features for the detectors and associated electronics.
Gamma-Ray Integrated Detectors (GRID) mission is a student project designed to use multiple gamma-ray detectors carried by nanosatellites (CubeSats), forming a full-time all-sky gamma-ray detection network that monitors the transient gamma-ray sky in the multi-messenger astronomy era. A compact CubeSat gamma-ray detector, including its hardware and firmware, was designed and implemented for the mission. The detector employs four Gd2Al2Ga3O12 : Ce (GAGG:Ce) scintillators coupled with four silicon photomultiplier (SiPM) arrays to achieve a high gamma-ray detection efficiency between 10 keV and 2 MeV with low power and small dimensions. The first detector designed by the undergraduate student team onboard a commercial CubeSat was launched into a Sun-synchronous orbit on October 29, 2018. The detector was in a normal observation state and accumulated data for approximately one month after on-orbit functional and performance tests, which were conducted in 2019.
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on orbit. SGD is complimentary to ASTRO-Hs Hard X-ray Imager covering the energy range of 5-80 keV. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes. The ASTRO-H mission is approved by ISAS/JAXA to proceed to a detailed design phase with an expected launch in 2014. In this paper, we present science drivers and concept of the SGD instrument followed by detailed description of the instrument and expected performance.
We present the Microchannel X-ray Telescope, a new light and compact focussing telescope that will be flying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science. The MXT design is based on the coupling of square pore micro-channel plates with a low noise pnCCD. MXT will provide an effective area of about 50 cmsq, and its point spread function is expected to be better than 3.7 arc min (FWHM) on axis. The estimated sensitivity is adequate to detect all the afterglows of the SVOM GRBs, and to localize them to better then 60 arc sec after five minutes of observation.