scholarly journals Onboard catalogue of known X-ray sources for SVOM/ECLAIRs

2020 ◽  
Vol 645 ◽  
pp. A18 ◽  
Author(s):  
N. Dagoneau ◽  
S. Schanne ◽  
J. Rodriguez ◽  
J.-L. Atteia ◽  
B. Cordier
Keyword(s):  
Energy Band ◽  
Gamma Ray ◽  
Background Level ◽  
High Energy ◽  
Low Noise ◽  
Field Of View ◽  
Large Field ◽  
Galactic Centre ◽  
Reconstruction Process ◽  
X Ray

The SVOM mission currently under development will carry various instruments, and in particular the coded-mask telescope ECLAIRs, with a large field of view of about 2 sr, operating in the 4–150 keV energy band. The main goal of ECLAIRs is to detect high-energy transients such as gamma-ray bursts. Its onboard trigger software will search for new hard X-ray sources appearing in the sky, as well as peculiar behaviour (e.g. strong outbursts) from known sources, in order to repoint the satellite to perform follow-up observations with its onboard narrow-field-of-view instruments. The presence of known X-ray sources must be disentangled from the appearance of new sources. This is done with the help of an onboard source catalogue, which we present in this paper. As an input we use catalogues of X-ray sources detected by Swift/BAT and MAXI/GSC and we study the influence of the sources on ECLAIRs’ background level and on the quality of the sky-image reconstruction process. We show that the influence of the sources depends on the pointing direction on the sky, on the energy band, and on the exposure time. In the Galactic centre, the contribution from known sources largely dominates the cosmic X-ray background, which is, on the contrary, the main background in sky regions lacking strong sources. We also demonstrate the need to clean the contributions of these sources in order to maintain a low noise level in the sky images and to maintain a low threshold for the detection of new sources without introducing false triggers. We briefly describe one of our cleaning methods and its challenges. Finally, we present the overall structure of the onboard catalogue and the way it will be used to perform the source cleaning and disentangle detections of new sources from outbursts of known sources.

scholarly journals The Future of X-Ray Time-Domain Surveys

2011 ◽  
Vol 7 (S285) ◽  
pp. 199-206
Author(s):  
Daryl Haggard ◽  
Gregory R. Sivakoff
Keyword(s):  
Time Domain ◽  
Gamma Ray ◽  
High Energy ◽  
Galactic Centre ◽  
Time Resolved ◽  
X Ray ◽  
Stellar Flares ◽  
Time Domain Data ◽  
Deep Fields ◽  
Energy Dependent

AbstractModern X-ray observatories yield unique insight into the astrophysical time domain. Each X-ray photon can be assigned an arrival time, an energy and a sky position, yielding sensitive, energy-dependent light curves and enabling time-resolved spectra down to millisecond time-scales. Combining those with multiple views of the same patch of sky (e.g., in the Chandra and XMM-Newton deep fields) so as to extend variability studies over longer baselines, the spectral timing capacity of X-ray observatories then stretch over 10 orders of magnitude at spatial resolutions of arcseconds, and 13 orders of magnitude at spatial resolutions of a degree. A wealth of high-energy time-domain data already exists, and indicates variability on timescales ranging from microseconds to years in a wide variety of objects, including numerous classes of AGN, high-energy phenomena at the Galactic centre, Galactic and extra-Galactic X-ray binaries, supernovæ, gamma-ray bursts, stellar flares, tidal disruption flares, and as-yet unknown X-ray variables. This workshop explored the potential of strategic X-ray surveys to probe a broad range of astrophysical sources and phenomena. Here we present the highlights, with an emphasis on the science topics and mission designs that will drive future discovery in the X-ray time domain.

scholarly journals First detection of the Crab Nebula at TeV energies with a Cherenkov telescope in a dual-mirror Schwarzschild-Couder configuration: the ASTRI-Horn telescope

2020 ◽  
Vol 634 ◽  
pp. A22 ◽  
Author(s):  
S. Lombardi ◽  
O. Catalano ◽  
S. Scuderi ◽  
L. A. Antonelli ◽  
G. Pareschi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
Statistical Significance ◽  
High Energy ◽  
Field Of View ◽  
Large Field ◽  
Mirror Reflection ◽  
Camera System ◽  
Cherenkov Telescope ◽  
The Crab Nebula

We report on the first detection of very high-energy gamma-ray emission from the Crab Nebula by a Cherenkov telescope in dual-mirror Schwarzschild-Couder (SC) configuration. This result has been achieved by means of the 4 m ASTRI-Horn telescope, operated on Mt. Etna, Italy, and developed in the context of the Cherenkov Telescope Array Observatory preparatory phase. The dual-mirror SC design is aplanatic and characterized by a small plate scale, which allows us to implement large cameras with a large field of view, with small-size pixel sensors and a high level of compactness. The curved focal plane of the ASTRI camera is covered by silicon photo-multipliers, managed by an unconventional front-end electronic system that is based on a customized peak-sensing detector mode. The system includes internal and external calibration systems, hardware and software for control and acquisition, and the complete data archiving and processing chain. These observations of the Crab Nebula were carried out in December 2018 during the telescope verification phase for a total observation time (after data selection) of 24.4 h, equally divided between on- and off-axis source exposure. The camera system was still under commission and its functionality was not yet completely exploited. Furthermore, due to recent eruptions of the Etna Volcano, the mirror reflection efficiency was reduced. Nevertheless, the observations led to the detection of the source with a statistical significance of 5.4σ above an energy threshold of ∼3 TeV. This result provides an important step toward the use of dual-mirror systems in Cherenkov gamma-ray astronomy. A pathfinder mini-array based on nine ASTRI-like telescopes with a large field-of-view is in the course of implementation.

scholarly journals Large field-of-view asymmetric masks for high-energy x-ray phase imaging with standard x-ray tube

2016 ◽  
Author(s):  
M. Endrizzi ◽  
A. Astolfo ◽  
B. Price ◽  
I. Haig ◽  
A. Olivo
Keyword(s):  
High Energy ◽  
Field Of View ◽  
Large Field ◽  
Phase Imaging ◽  
X Ray

scholarly journals Asymmetric masks for large field-of-view and high-energy X-ray phase contrast imaging

2016 ◽  
Vol 11 (12) ◽  
pp. C12009-C12009 ◽  
Author(s):  
M. Endrizzi ◽  
A. Astolfo ◽  
B. Price ◽  
I. Haig ◽  
A. Olivo
Keyword(s):  
Phase Contrast ◽  
High Energy ◽  
Field Of View ◽  
Phase Contrast Imaging ◽  
Large Field ◽  
Contrast Imaging ◽  
X Ray

STATUS AND PERSPECTIVES OF GLAST GAMMA RAY EXPERIMENT

2005 ◽  
Vol 20 (29) ◽  
pp. 7009-7011
Author(s):  
◽  
N. GIGLIETTO
Keyword(s):  
Active Galactic Nuclei ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Field Of View ◽  
Current Status ◽  
Large Field ◽  
Diffuse Emission ◽  
Large Area

GLAST, the Gamma-ray Large Area Telescope, is a satellite-based experiment able to measure the cosmic gamma-ray flux in the energy range between 20 MeV and 300 GeV or above. The sensitivity is more than 30 times respect to EGRET and the good spatial and time resolution over a large field of view let us to cover a large variety of high energy phenomena. In particular GLAST will be able to study both diffuse emission and point-like gamma ray sources, including active galactic nuclei, gamma ray bursts, pulsars and supernova remnants. In addition, the potentialities of GLAST to explore rare or exotic phenomena like supersymmetric dark matter annihilations will be shown. The present knowledge of the science opportunities that the GLAST experiment can explore will be completed with the detector description and the current status of the experiment.

Novel Near Field Detector for Three-Dimensional X-Ray Diffraction Microscopy

MRS Advances ◽  
2018 ◽  
Vol 3 (39) ◽  
pp. 2341-2346 ◽  
Author(s):  
Scott Annett ◽  
Sergio Morelhao ◽  
Darren Dale ◽  
Stefan Kycia
Keyword(s):  
New Technologies ◽  
Spatial Information ◽  
Near Field ◽  
Three Dimensional ◽  
High Energy ◽  
Field Of View ◽  
Large Field ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray

AbstractThree dimensional X-ray diffraction (3DXRD) microscopy is a powerful technique that provides crystallographic and spatial information of a large number, of the order of thousands, of crystalline grains in a sample simultaneously. A key component of every 3DXRD microscopy experiment is the near field detector that provides high resolution spatial information of the grains. In this work we present a novel design for a semi-transparent, 16 megapixel near field detector. As opposed to a typical single scintillator phosphor detector, this design, we call the Quad Near Field Detector, uses four quadrants. It has a total field of view is 5.3 mm x 5.3 mm with an effective pixel size of 1.3 µm x 1.3 µm. The detector’s relatively large field of view can be used to obtain higher order diffraction spots which we anticipate will lead to improved spatial resolution in grain reconstructions. The large field of view can also enable the detector to be positioned further from the sample, in this way increasing the working distance and enabling larger environmental cells for in-situ studies. Many alignment parameters can be resolved by careful mechanical design. For this reason a novel translation stage for focusing the microscopes was developed, tested, and implemented. The near field detector was calibrated and characterized at the Cornell High Energy Synchrotron Source. The operational feasibility of such a multi-plate detector demonstrated in this work paves the way for new technologies in instrumentation of 3DXRD microscopy.

scholarly journals Staircase array of inclined refractive multi-lenses for large field of view pixel super-resolution scanning transmission hard X-ray microscopy

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Talgat Mamyrbayev ◽  
Katsumasa Ikematsu ◽  
Hidekazu Takano ◽  
Yanlin Wu ◽  
Kenji Kimura ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Super Resolution ◽  
High Energy ◽  
Two Dimensions ◽  
Field Of View ◽  
Large Field ◽  
Acquisition Time ◽  
X Rays ◽  
X Ray ◽  
Scanning Transmission

Owing to the development of X-ray focusing optics during the past decades, synchrotron-based X-ray microscopy techniques allow the study of specimens with unprecedented spatial resolution, down to 10 nm, using soft and medium X-ray photon energies, though at the expense of the field of view (FOV). One of the approaches to increase the FOV to square millimetres is raster-scanning of the specimen using a single nanoprobe; however, this results in a long data acquisition time. This work employs an array of inclined biconcave parabolic refractive multi-lenses (RMLs), fabricated by deep X-ray lithography and electroplating to generate a large number of long X-ray foci. Since the FOV is limited by the pattern height if a single RML is used by impinging X-rays parallel to the substrate, many RMLs at regular intervals in the orthogonal direction were fabricated by tilted exposure. By inclining the substrate correspondingly to the tilted exposure, 378000 X-ray line foci were generated with a length in the centimetre range and constant intervals in the sub-micrometre range. The capability of this new X-ray focusing device was first confirmed using ray-tracing simulations and then using synchrotron radiation at BL20B2 of SPring-8, Japan. Taking account of the fact that the refractive lens is effective for focusing high-energy X-rays, the experiment was performed with 35 keV X-rays. Next, by scanning a specimen through the line foci, this device was used to perform large FOV pixel super-resolution scanning transmission hard X-ray microscopy (PSR-STHXM) with a 780 ± 40 nm spatial resolution within an FOV of 1.64 cm × 1.64 cm (limited by the detector area) and a total scanning time of 4 min. Biomedical implant abutments fabricated via selective laser melting using Ti–6Al–4V medical alloy were measured by PSR-STHXM, suggesting its unique potential for studying extended and thick specimens. Although the super-resolution function was realized in one dimension in this study, it can be expanded to two dimensions by aligning a pair of presented devices orthogonally.

Numerical analysis of shift error in X-ray phase contrast imaging for large field of view

2017 ◽  
Vol 34 (1) ◽  
pp. 8
Author(s):  
Jianheng Huang ◽  
Yaohu Lei ◽  
Xin Liu ◽  
Jinchuan Guo ◽  
Ji Li ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Phase Contrast ◽  
Field Of View ◽  
Phase Contrast Imaging ◽  
Large Field ◽  
Contrast Imaging ◽  
X Ray

scholarly journals Gamma-Ray and Neutrino Signals from Accretion Disk Coronae of Active Galactic Nuclei

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 36
Author(s):  
Yoshiyuki Inoue ◽  
Dmitry Khangulyan ◽  
Akihiro Doi
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Thermal Activity ◽  
X Ray ◽  
Cascade Models ◽  
Coronal Activity ◽  
Ngc 1068 ◽  
High Energy Particles

To explain the X-ray spectra of active galactic nuclei (AGN), non-thermal activity in AGN coronae such as pair cascade models has been extensively discussed in the past literature. Although X-ray and gamma-ray observations in the 1990s disfavored such pair cascade models, recent millimeter-wave observations of nearby Seyferts have established the existence of weak non-thermal coronal activity. In addition, the IceCube collaboration reported NGC 1068, a nearby Seyfert, as the hottest spot in their 10 yr survey. These pieces of evidence are enough to investigate the non-thermal perspective of AGN coronae in depth again. This article summarizes our current observational understanding of AGN coronae and describes how AGN coronae generate high-energy particles. We also provide ways to test the AGN corona model with radio, X-ray, MeV gamma ray, and high-energy neutrino observations.

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