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S. Mate

Publications and source records attributed to S. Mate.

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SVOM/ECLAIRs detection plane: main features and performance

The detection plane of the high-energy transient camera ECLAIRs onboard SVOM is made of 200 XRDPIX detection modules, each consisting of a matrix of $8\times 4$ Schottky-type CdTe detectors hybridized with the low-noise and low-consumption ASIC IDeF-X. The 6400 detectors are operated at -20{\deg}C and reverse biased at -300 V, reaching a low energy threshold of 4 keV. The 20 us time resolution readout electronics works in photon counting mode classifying detected events as single or multiple events and measuring the deposited energy in real time. In this paper, we present the detection plane sub-systems and their main features. We also discuss its overall performances as measured both on ground and in-flight, showing compliance with the ECLAIRs science requirements.

astro-ph.IM

The GRB joint scientific analysis pipeline of the ECLAIRs and GRM instruments on board SVOM

The study of the prompt high-energy emission of Gamma-Ray Bursts (GRBs) with SVOM relies on the observations performed by ECLAIRs (4-150 keV) and the Gamma-Ray Monitor (GRM, 0.015-5 MeV), the two wide field-of-view instruments on board the satellite. In this article, we introduce the eclgrm pipelines running at the French Science Center of SVOM, which combine the ECLAIRs and GRM data to generate scientific data products describing the GRB broad-band temporal and spectral properties. The architecture of the pipelines is presented, as well as their activation following each onboard trigger, and their workflow. The statistical data analysis methods employed by the pipelines are described, along with the scientific data products that are created in real time or from the full event data. We also present the eclgrm-ui user interface which allows the scientists on shift to monitor the automated data processings in the pipelines, and to optimize the analysis results interactively.

astro-ph.HE

Detection of short high-energy transients in the localuniverse with SVOM/ECLAIRs

The coincidental detection of the gravitational wave event GW 170817 and the associated gamma-ray burst GRB 170817A marked the advent of multi-messenger astronomy and represented a milestone in the study of GRBs. In this context, the launch of SVOM in mid-2022, with its two wide-field high-energy instruments ECLAIRs and GRM, will foster the possibilities of coincidental transient detection with gravitational waves and gamma-rays events. The purpose of this paper is to assess the ability of SVOM/ECLAIRs to detect and quickly characterize high-energy transients in the local Universe (z<0.3), and to discuss the contribution of this instrument to multi-messenger astronomy and to gamma-ray burst(GRB) astrophysics in the 2020s. A list of local HE transients, along with their main characteristics, is constructed through an extensive literature survey. The detectability of these transients with ECLAIRs is assessed with detailed simulations using tools developed for the SVOM mission, including a GEANT4 simulation of the energy response and a simulated trigger algorithm representative of the onboard trigger algorithm. The SNR for almost all detections will be sufficiently high to allow the on-board ECLAIRs trigger algorithm to detect and derive the localisation of the transient, transmitting it to the SVOM satellite and ground-based instruments. Coupled with the anti-solar pointing strategy of SVOM, this will enable an optimal follow-up of the events, allowing the observation of their afterglows, supernovae/kilonovae counterparts, and host galaxies. We conclude the paper with a discussion of the unique contribution expected from SVOM and of the possibility of simultaneous GW detection for each type of transient in our sample.

astro-ph.HE

Designing large pixelated CdTe detection planes for hard X-ray transients detection

We discuss the need for very large detection planes for the detection of hard X-ray transients in the multi-messenger era that started with the quasi-simultaneous detection of GRB~170817A by \textit{Fermi}/GBM and \textit{INTEGRAL}/SPI on one hand and the gravitational waves event GW 170817, detected by the LVC collaboration, on the other hand. Then, we present a brief survey of current and future instruments and their expected sensitivity, pointing the fact that the gain in the number of GRBs is achieved by future projects thanks to their larger field of view rather than to their larger effective area. Based on our experience with \textit{SVOM}/ECLAIRs, we then address various problems associated with the realization of very large detection planes (\mbox{$\ge 1 \mathrm m^{2}$}), and we demonstrate that CdTe detectors are well suited for this task. We conclude with a discussion of some key parameters that must be taken into account in the realization of instruments based on these detectors. We hope that this paper will motivate the elaboration of detailed proposals of large area wide-field hard X-ray monitors that will be crucially needed in the next decade.

astro-ph.IM

A tale of two transients: GW170104 and GRB170105A

We present multi-wavelength follow-up campaigns by the AstroSat-CZTI and GROWTH collaborations to search for an electromagnetic counterpart to the gravitational wave event GW170104. At the time of the GW170104 trigger, the AstroSat CZTI field-of-view covered 50.3\% of the sky localization. We do not detect any hard X-ray (>100 keV) signal at this time, and place an upper limit of $\approx 4.5 \times 10^{-7}~{\rm erg~cm}^{-2}{\rm~s}^{-1}$ for a 1\,s timescale. Separately, the ATLAS survey reported a rapidly fading optical source dubbed ATLAS17aeu in the error circle of GW170104. Our panchromatic investigation of ATLAS17aeu shows that it is the afterglow of an unrelated long, soft GRB~170105A, with only a fortuitous spatial coincidence with GW170104. We then discuss the properties of this transient in the context of standard long GRB afterglow models.

astro-ph.HE