GRM (Gamma-Ray Monitor) is the high energy detector on-board the future Chinese-French satellite SVOM (Space-based multi-band astronomical Variable Object Monitor) which is dedicated to Gamma-Ray Burst (GRB) studies. This paper presents the investigation of the on-board counting rate trigger algorithms of GRM. The trigger threshold and trigger efficiency based on the given GRB sample are calculated with the algorithms. The trigger characteristics of GRM and ECLAIRs are also analyzed. In addition, the impact of solar flares on GRM is estimated, and the method to distinguish solar flares from GRBs is investigated.
SVOM (Space-based multi-band astronomical Variable Object Monitor) is a future Chinese-French satellite mission which is dedicated to Gamma-Ray Burst (GRB) studies. Its anti-solar pointing strategy makes the Earth cross the field of view of its payload every orbit. In this paper, we present the variations of the gamma-ray background of the two high energy instruments aboard SVOM, the Gamma-Ray Monitor (GRM) and ECLAIRs, as a function of the Earth position. We conclude with an estimate of the Earth influence on their sensitivity and their GRB detection capability.
The GRB joint scientific analysis pipeline of the ECLAIRs and GRM instruments on board SVOM
Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3（蒙彼利埃宇宙与粒子实验室，蒙彼利埃大学，法国国家科学研究中心/法国国家核子和粒子物理研究所）；Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris（索邦大学，法国国家科学研究中心，联合研究单位7095，巴黎天体物理学研究所）；Institut Universitaire de France（法兰西学院）；INAF –Osservatorio Astronomico di Brera（意大利国家天体物理研究所-布雷拉天文台）
SVOM is a Sino-French space mission targeting high-energy transient astrophysical objects such as gamma-ray bursts. The soft X-ray part of the spectrum is covered by the Micro-channel X-ray Telescope (MXT) which is a narrow field telescope designed to precisely localize X-ray sources. This paper presents the method implemented on-board to characterize and localize X-ray sources with the MXT. A specific localization method was developed to accommodate the optical system of the MXT, which is based on "Lobster-Eye" grazing incidence micro-pore optics. For the first time, the algorithm takes advan…
The Microchannel X-ray Telescope (MXT) will be the first focusing X-ray telescope based on a "Lobster-Eye" optical design to be flown on Sino-French mission SVOM. SVOM will be dedicated to the study of Gamma-Ray Bursts and more generally time-domain astrophysics. The MXT telescope is a compact (focal length ~ 1.15 m) and light (< 42 kg) instrument, sensitive in the 0.2--10 keV energy range. It is composed of an optical system, based on micro-pore optics (MPOs) of 40 micron pore size, coupled to a low-noise pnCDD X-ray detector. In this paper we describe the expected scientific performance of t…
Scientific performance of on-board analyses for the SVOM X-ray telescope MXT
Université Paris-Saclay（巴黎萨克雷大学）；CNRS/IN2P3, IJCLab（法国国家科学研究中心/欧洲核子研究组织，IJCLab）；AIM-CEA/DRF/Irfu/Departement d’Astrophysique, CNRS, Universite Paris-Saclay, Universite Paris Cite（AIM-CEA/DRF/Irfu天体物理学系，法国国家科学研究中心，巴黎萨克雷大学，巴黎 Cité 大学）；Centre National d’Etudes Spatiales（法国国家空间研究中心）；School of Physics and Astronomy, University of Leicester（莱斯特大学物理与天文学院）；Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS（斯特拉斯堡天文台，斯特拉斯堡大学，法国国家科学研究中心）
The Space-based multi-band astronomical Variable Object Monitor (SVOM) mission is dedicated to the detection, localization and broad-band study of Gamma-Ray Bursts (GRBs) and other high-energy transient phenomena. The Gamma Ray Monitor (GRM) onboard is designed to observe the GRBs up to 5 MeV. With this instrument one of the key GRB parameter, Epeak, can be easily measured in the hard x-ray band. It can achieve a detection rate of 100 GRBs per year which ensures the scientific output of SVOM.
We present the Micro-channel X-ray Telescope (MXT), a new narrow-field (about 1°) telescope that will be flying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science, scheduled for launch in 2021. MXT is based on square micro pore optics (MPOs), coupled with a low noise CCD. The optics are based on a "Lobster Eye" design, while the CCD is a focal plane detector similar to the type developed for the seven eROSITA telescopes. MXT is a compact and light (<35 kg) telescope with a 1 m focal length, and it will provide an effective area of about 45 cmsq on axis at 1 keV. The MXT PSF i…
The data analysis pipeline for the Microchannel X-ray Telescope on board the SVOM mission
Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS（斯特拉斯堡天文台，斯特拉斯堡大学，法国国家科学研究中心）；AIM-CEA/DRF/Irfu/Departement d’Astrophysique, CNRS, Universite Paris-Saclay, Universite Paris Cite（天体物理研究所，法国国家科学研究中心，巴黎萨克雷大学，巴黎西岱大学）；Centre National d’Etudes Spatiales, Centre spatial de Toulouse（法国国家空间研究中心，图卢兹航天中心）
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is an approved satellite mission for Gamma-Ray Burst (GRB) studies, developed in cooperation between the Chinese National Space Agency (CNSA), the Chinese Academy of Sciences (CAS), the French Space Agency (CNES) and French laboratories. SVOM entered Phase B in 2014 and is scheduled for launch in 2021. SVOM will provide fast and accurate GRB localizations, and determine the temporal and spectral properties of the GRB emission, thanks to a set of 4 on-board instruments. The trigger system of the coded-mask telescope ECLAIRs…
The Microchannel X-ray Telescope on board the SVOM mission: in-flight scientific performance
AIM-CEA/DRF/Irfu/Departement d’Astrophysique, CNRS, Universite Paris-Saclay, Universite Paris Cite（天体物理学与核物理研究所，法国国家科学研究中心，巴黎萨克雷大学，巴黎 Cité 大学）；Centre National d’Etudes Spatiales, Centre spatial de Toulouse（法国国家空间研究中心，图卢兹航天中心）；Space Park Leicester, University of Leicester（莱斯特大学，莱斯特太空公园）；College of Science and Engineering, School of Mathematics and Physics, Kanazawa University（金泽大学，理学院，数学与物理系）
The SVOM mission under development will carry four instruments, and in particular the coded-mask telescope named ECLAIRs, with a large field of view of about 2 sr, operating in the 4-150 keV energy band. The trigger software on board ECLAIRs will search for high-energy transients such as gamma-ray bursts and peculiar behaviour (e.g. strong outbursts) from known X-ray sources, in order to repoint the satellite to perform follow-up observations with the onboard narrow field of view instruments. The image trigger, one of the two algorithms implemented in the software on board ECLAIRs, produces im…
We report on an on-going test campaign of more than 5000 Schottky CdTe detectors (4x4x1 mm^3), over a sample of twelve thousands, provided by Acrorad Co., Ltd (Japan). 6400 of these detectors will be used to build the detection plane of the ECLAIRs camera on the Chinese-French gamma-ray burst mission SVOM. These tests are mandatory to fulfill the prime requirement of ECLAIRs to detect gamma-ray burst photons down to 4 keV. The detectors will be operated at -20C under a reverse bias of 600 V. We found that 78% of the detectors already tested could be considered for the flight model. We measured…
The Space multi-band Variable Object Monitor (SVOM) is a proposed Chinese astronomical satellite, dedicated to the detection, localization and measurement of the gamma-ray bursts (GRBs) on the cosmological scale. An efficient algorithm is developed for the purpose of onboard star extraction from the CCD images obtained with the Visible Telescope (VT) on board SVOM. The CCD pixel coordinates of the reference stars will be used to refine the astronomical position of the satellite, which will facilitate trigger rapid ground-based follow-up obsevations of the GRBs. In this algorithm, the image is …
For several decades now, wide-field coded mask cameras have been used with success to localise Gamma-ray bursts (GRBs). In these instruments, the event count rate is dominated by the photon background due to their large field of view and large effective area. It is therefore essential to estimate the instrument background expected in orbit during the early phases of the instrument design in order to optimise the scientific performances of the mission. We present here a detailed study of the instrument background and sensitivity of the coded-mask camera for X- and Gamma-rays (CXG) to be used in…
CEA Paris-Saclay, Institut de Recherche sur les lois Fondamentales de l’Univers（法国原子能和替代能源委员会巴黎萨克雷中心基础定律研究所）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理重点实验室）；Aix Marseille Université, CNRS, CNES, LAM（艾克斯-马赛大学）；IRAP, Université de Toulouse, CNRS, CNES（图卢兹大学）；Université Paris Cité, CNRS, CEA, Astroparticule et Cosmologie（巴黎西岱大学）；Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris（索邦大学）
The soft gamma-ray telescope ECLAIRs with its Scientific Trigger Unit is in charge of detecting Gamma-Ray Bursts (GRBs) on-board the future SVOM satellite. Using the "scientific software model" (SSM), we study the efficiency of both implemented trigger algorithms, the Count-Rate Trigger for time-scales below 20s and the Image Trigger for larger ones. The SMM provides a simulation of ECLAIRs with photon projection through the coded-mask onto the detection plane. We developed an input GRB database for the SSM based on GRBs light curves detected by the Fermi GBM instrument. We extrapolated the GR…
To take advantage of the astrophysical potential of Gamma-Ray Bursts (GRBs), Chinese and French astrophysicists have engaged the SVOM mission (Space-based multi-band astronomical Variable Objects Monitor). Major advances in GRB studies resulting from the synergy between space and ground observations, the SVOM mission implements space and ground instrumentation. The scientific objectives of the mission put a special emphasis on two categories of GRBs: very distant GRBs at z$>$5 which constitute exceptional cosmological probes, and faint/soft nearby GRBs which allow probing the nature of the pro…
We present the SVOM (Space-based multi-band astronomical Variable Object Monitor) mission, that is being developed in cooperation between the Chinese National Space Agency (CNSA), the Chinese Academy of Science (CAS) and the French Space Agency (CNES). Its scientific objectives include the study of the GRB phenomenon, GRB physics and progenitors, cosmology, and fundamental physics. SVOM is designed to detect all known types of Gamma-Ray Bursts (GRBs), to provide fast and reliable GRB positions, to measure the broadband spectral characteristics and temporal properties of the GRB prompt emission…
We present ECLAIRs, the Gamma-ray burst (GRB) trigger camera to fly on-board the Chinese-French mission SVOM. ECLAIRs is a wide-field ($\sim 2$\,sr) coded mask camera with a mask transparency of 40\% and a 1024 $\mathrm{cm}^2$ detection plane coupled to a data processing unit, so-called UGTS, which is in charge of locating GRBs in near real time thanks to image and rate triggers. We present the instrument science requirements and how the design of ECLAIRs has been optimized to increase its sensitivity to high-redshift GRBs and low-luminosity GRBs in the local Universe, by having a low-energy t…
The on-board Scientific Trigger Unit (UTS) is designed to detect Gamma Ray Bursts (GRBs) in real-time, using the data produced by the ECLAIRs camera, foreseen to equip the future French-Chinese satellite mission SVOM (Space-based Variable Objects Monitor). The UTS produces GRB alerts, sent to the ground for GRB follow-up observations, and requests the spacecraft slew to repoint its narrow field instruments onto the GRB afterglow. Because of the diversity of GRBs in duration and variability, two simultaneously running GRB trigger algorithms are implemented in the UTS, the so called Image Trigge…
