Detection of gamma-ray bursts with the ECLAIRs instrument onboard the space mission SVOM
Description
Discovered in the early 1970's, gamma-ray bursts (GRBs) are amazing cosmic phenomena appearing randomly on the sky and releasing large amounts of energy mainly through gamma-ray emission. Although their origin is still under debate, they are believed to be produced by some of the most violent explosions in the Universe leading to the formation of stellar black-holes. GRBs are detected by their prompt emission, an intense short burst of gamma-rays (from a few milliseconds to few minutes), and are followed by a lived-afterglow emission observed on longer timescales from the X-ray to the radio domain. My thesis participates to the development of the SVOM mission, which a Chinese-French mission to be launched in 2021, devoted to the study of GRBs and involving space and ground instruments. My work is focussed on the main instrument ECLAIRs, a hard X-ray coded mask imaging camera, in charge of the near real-time detection and localization of the prompt emission of GRBs. During my thesis, I studied the scientific performances of ECLAIRs and in particular the number of GRBs expected to be detected by ECLAIRs and their characteristics. For this purpose, I performed simulations using the prototypes of the embedded trigger algorithms combined with the model of the ECLAIRs instrument. The input data of the simulations include a background model and a synthetic population of gamma-ray bursts generated from existing catalogs (CGRO, HETE-2, Fermi and Swift). As a result, I estimated precisely the ECLAIRs detection efficiency of the algorithms and I predicted the number of GRBs to be detected by ECLAIRs: 40 to 70 GRBs per year. Moreover, the study highlighted that ECLAIRs will be particularly sensitive to the X-ray rich GRB population. My thesis provided additional studies about the localization performance, the rate of false alarm and the characteristics of the triggers of the algorithms. Finally, I also proposed two new methods for the detection of GRBs.The preliminary results were very promising and demonstrate that the sensitivity of ECLAIRs to the short GRBs (an interesting population due to the predicted association with gravitational waves) could be improved further. (author)
Abstract (French)
Les sursauts gamma sont des evenements fascinants de par leur origine longtemps restee mysterieuse, leur apparition imprevisible dans le ciel, et la formidable energie qu'ils liberent sous forme de bouffees de rayonnement gamma. Decouverts fortuitement au debut des annees 1970, ils se traduisent par un intense flash de rayons gamma de breve duree (de quelques ms a quelques min), appele emission prompte, suivi d'une emission longue, appelee remanence, qui decroit rapidement, en emettant depuis les rayons X jusqu'au domaine radio. L'origine des sursauts gamma est encore largement discutee mais ces phenomenes extremes sont tres vraisemblablement associes a la formation de nouveaux trous noirs stellaires. Mon sujet de these se situe au coeur de la mission sino-francaise SVOM dont le lancement du satellite est prevu en 2021, qui scrutera le ciel pour observer les sursauts avec une precision inegalee, associant observations spatiales et terrestres. Mon travail concerne l'instrument principal de la mission, le telescope spatial ECLAIRs. Il s'agit d'une camera a masque code sensible aux rayons X et gamma de basse energie, en charge de la detection et de la localisation de l'emission prompte des sursauts. Durant mon travail de these, j'ai travaille sur les performances scientifiques de l'instrument ECLAIRs et j'ai en particulier estime le nombre de sursauts qui seront detectes et leurs caracteristiques. Pour cela, j'ai mis en place des simulations de performances utilisant les prototypes des algorithmes de detection embarques combines au modele de l'instrument ECLAIRs. Les donnees en entree des simulations comportent un bruit de fond simule, et une population synthetique de sursauts gamma generee a partir de catalogues existants issus des observations des missions anterieures (CGRO, HETE-2, Swift et Fermi). Mon etude a permis d'estimer finement l'efficacite de detection d'ECLAIRs et predit un taux de sursauts attendu par ECLAIRs entre 40 et 70 sursauts par an. Par ailleurs, mon travail a montre qu'ECLAIRs sera particulierement sensible a une population de sursauts tres riches en rayons X, population encore mal connue. Ma these presente plusieurs autres etudes complementaires portant sur la performance de localisation, le taux de fausses alertes et les caracteristiques des declenchements des algorithmes. Enfin, j'ai propose deux nouvelles methodes originales de detection de sursauts dont les resultats preliminaires presentes dans ma these sont tres encourageants. Ils montrent que la sensibilite d'ECLAIRs aux sursauts courts (population d'interet particulier en raison de son lien attendu avec les ondes gravitationnelles) peut etre encore amelioree
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Additional details
Additional titles
- Original title (French)
- La detection des sursauts gamma par le telescope ECLAIRs pour la mission spatiale SVOM
Identifiers
Publishing Information
- Imprint Pagination
- 301 p.
- Report number
- FRCEA-TH--9210
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 49015640
- Subject category
- S79: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- ALGORITHMS; ASTRONOMY; BLACK HOLES; COSMIC GAMMA BURSTS; GAMMA RADIATION; SENSITIVITY; SIMULATION
- Descriptors DEC
- COSMIC RADIATION; ELECTROMAGNETIC RADIATION; IONIZING RADIATIONS; MATHEMATICAL LOGIC; PRIMARY COSMIC RADIATION; RADIATIONS
Optional Information
- Notes
- 122 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/; Also available from Le Service Commun de la Documentation de l'Universite Paris-Sud, Bat 407 - 91405 Orsay Cedex (France)