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.
Proteolysis within the membrane is a recent concept in biology. Rhomboid intramembrane serine proteases are conserved in evolution and serve as key switches in diverse cellular pathways ranging from ...signaling to protein degradation. Since deregulation of intramembrane proteolysis can lead to severe diseases including neurodegenerative disorders, dissecting their enzymatic function and specificity becomes crucial. As membrane proteins, their solubilization, and purification are technically challenging. As a start point for a comprehensive in vitro characterization of eukaryotic rhomboid proteases, we depict in this chapter a robust workflow to find the best conditions to obtain pure and active enzymes from a bacterial expression system. To monitor the integrity of their active site and visualize substrate cleavage, various established activity assays including activity-based labeling and gel-based cleavage assays are described. These methods are illustrated by use of the Escherichia coli rhomboid protease GlpG and human RHBDL2 as an example.
We present the updated INTEGRAL catalogue of gamma-ray bursts (GRBs) observed between December 2002 and February 2012. The catalogue contains the spectral parameters for 59 GRBs localized by the ...INTEGRAL Burst Alert System (IBAS). We used the data from the two main instruments on board the INTEGRAL satellite: the spectrometer SPI (Spectrometer on INTEGRAL) nominally covering the energy range 20 keV-8 MeV, and the imager IBIS (the Imager on Board the INTEGRAL Satellite) operating in the range from 15 keV to 10 MeV. For the spectral analysis we applied a new data extraction technique, developed to explore the energy regions of highest sensitivity for both instruments, SPI and IBIS. It allowed us to analyse the GRB spectra over a broad energy range and to determine the bursts' spectral peak energies. The spectral analysis was performed on the whole sample of GRBs triggered by IBAS, including all the events observed in the period December 2002 to February 2012. The catalogue contains the trigger times, burst coordinates, positional errors, durations, and peak fluxes for 28 unpublished GRBs observed between September 2008 and February 2012. The light curves in the 20-200 keV energy band of these events were derived using IBIS data. We compare the prompt emission properties of the INTEGRAL GRB sample with the BATSE and Fermi samples.
We discuss applications of the study of the new and barely explored class of changing-look (CL) narrow-line Seyfert 1 (NLS1) galaxies and comment on their detection with the space mission SVOM (Space ...Variable Objects Monitor). We highlight the case of NGC 1566, which is outstanding in many respects, for instance as one of the nearest known CL AGN undergoing exceptional outbursts. Its NLS1 nature is discussed, and we take it as a nearby prototype for systems that could be discovered and studied in the near future, including with SVOM. Finally, we briefly examine the broader implications and applications of CL events in NLS1 galaxies and show that such systems, once discovered in larger numbers, will greatly advance our understanding of the physics of the environment of rapidly growing supermassive black holes. This White Paper is part of a sequence of publications which explore aspects of our understanding of (CL) NLS1 galaxy physics with future missions.
SPI: The spectrometer aboard INTEGRAL Vedrenne, G.; Roques, J.-P.; Schönfelder, V. ...
Astronomy and astrophysics (Berlin),
11/2003, Letnik:
411, Številka:
1
Journal Article
Recenzirano
Odprti dostop
SPI is a high spectral resolution gamma-ray telescope on board the ESA mission INTEGRAL (International Gamma Ray Astrophysics Laboratory). It consists of an array of 19 closely packed germanium ...detectors surrounded by an active anticoincidence shield of BGO. The imaging capabilities of the instrument are obtained with a tungsten coded aperture mask located 1.7 m from the Ge array. The fully coded field-of-view is $16\deg$, the partially coded field of view amounts to $31\deg$, and the angular resolution is $2.5\deg$. The energy range extends from 20 keV to 8 MeV with a typical energy resolution of 2.5 keV at 1.3 MeV. Here we present the general concept of the instrument followed by a brief description of each of the main subsystems. INTEGRAL was successfully launched in October 2002 and SPI is functioning extremely well.
The Microchannel X-ray Telescope (MXT) will be the first focusing X-ray telescope based on a narrow field “Lobster-Eye” optical design to be flown on a satellite, namely the 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
μ
m pore size, coupled to a low-noise pnCDD X-ray detector. In this paper we describe the expected scientific performance of the MXT telescope, based on the End-to-End calibration campaign performed in fall 2021, before the integration of the SVOM payload on the satellite.
SVOM
(Space-based multi-band astronomical Variable Objects Monitor) is a Sino-French space mission dedicated to the study of Gamma-Ray Bursts (GRBs) in the next decade, capable to detect and localise ...the GRB emission, and to follow its evolution in the high-energy and X-ray domains, and in the visible and NIR bands. The satellite carries two wide-field high-energy instruments: a coded-mask gamma-ray imager (ECLAIRs; 4–150 keV), and a gamma-ray spectrometer (GRM; 15–5500 keV) that, together, will characterise the GRB prompt emission spectrum over a wide energy range. In this paper we describe the performances of the ECLAIRs and GRM system with different populations of GRBs from existing catalogues, from the classical ones to those with a possible thermal component superimposed to their non-thermal emission. The combination of ECLAIRs and the GRM will provide new insights also on other GRB properties, as for example the spectral characterisation of the subclass of short GRBs showing an extended emission after the initial spike.
We provide first constraints on the morphology of the 511 keV line emission from the galactic centre region on basis of data taken with the spectrometer SPI on the INTEGRAL gamma-ray observatory. The ...data suggest an azimuthally symmetric galactic bulge component with FWHM of ~$9\ensuremath{^\circ}$ with a $2\sigma$ uncertainty range covering $6\ensuremath{^\circ}{-}18\ensuremath{^\circ}$. The 511 keV line flux in the bulge component amounts to $9.9^{+4.7}_{-2.1} \times 10^{-4}$ ph cm-2 s-1. No evidence for a galactic disk component has been found so far; upper $2\sigma$ flux limits in the range $(1.4{-}3.4) \times 10^{-3}$ ph cm-2 s-1 have been obtained that depend on the assumed disk morphology. These limits correspond to lower limits on the bulge-to-disk ratio of $0.3{-}0.6$.
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