Description du sujet de thèse

COMCUBE-S is a swarm of nanosatellites designed to study gamma-ray bursts (GRBs). The mission was recently selected by the European Space Agency (ESA) with a view to launching a constellation of 27 gamma-ray nanosatellites in the middle of 2030s. An intermediate in-orbit demonstration mission with two nanosatellites is planned for 2030.
The aim of this thesis is to contribute to the development of COMCUBE-S for multi-wavelength astronomy. Our understanding of a variety of transient sources detected by COMCUBE-S in gamma rays will benefit from rapid follow-up at other wavelengths. These include GRBs, active galactic nuclei (AGNs), microquasars, soft gamma-ray repeaters and cataclysmic variables. The large volume of alerts generated by COMCUBE-S, on the order of several per day, will be processed automatically by a broker infrastructure such as FINK before being sent to the follow-up facilities and scientific teams.
The thesis project comprises three main parts: (i) the improvement of source localisation capabilities using artificial intelligence, (ii) the simulation of COMCUBE-S's detection of transient sources on the basis of their astrophysical properties, and (iii) the development of scientific modules in FINK for the automated management of alerts generated by the constellation.
COMCUBE-S will implement new aspects of inter-satellite links to produce rapid alert notifications with automatic source positioning. An initial localisation of sources will be obtained from the count rates of detectors throughout the constellation, which will be automatically transmitted to the ground in case of a triggering event. The method was originally developed for the localisation of GRBs by the CGRO-BATSE instrument, but its application to a large number of detectors spread over several satellites represents a new approach. The PhD student will develop a new localisation method based on the use of an artificial neural network trained with simulated data. He will use a detailed numerical model of a nanosatellite to predict the count rates of all detectors as a function of source position, spectrum and flux.
In the second part of the thesis, the PhD student will study the detection with COMCUBE-S of various astrophysical transient sources (GRBs, AGNs, etc.). He will use several source catalogues to describe the emission spectrum and variability of the astrophysical objects studied. Using simulations of the COMCUBE-S response function, he will evaluate the detection rate of each type of source and the localisation accuracy, based on the work carried out in the first part of the thesis.
Finally, the PhD student will use the simulated COMCUBE-S detections to build new scientific modules in the FINK broker developed at IJCLab. The aim is to provide a classification of transients in real time, in order to automatically select the most promising alerts to be sent to the General Coordinated Network (GCN) for follow-up observations at several wavelengths.
For his or her simulations, the PhD student will benefit greatly from the development and performance evaluation of the COMCUBE-S Compton gamma-ray telescope, which will be carried out at IJCLab during the thesis in collaboration with CEA-Irfu and University College Dublin. He or she will be able to take an active part in the laboratory instrumentation work and in the analysis of the data collected during the instrument tests. It will be very instructive for the student to use this laboratory data for simulations of space mission performance and astrophysical application.

Contexte de travail

The Irène Joliot-Curie Physics Laboratory of 2 Infinities (IJCLab) is a UMR under the supervision of the CNRS (IN2P3), the University of Paris-Saclay and the University of Paris is located on the campus of the University of Paris -Saclay in Orsay. The laboratory is located on the campus of the Université Paris-Sud, Université Paris-Saclay in Orsay. The campus is located 20 km south of Paris and easily accessible by RER in 35 minutes.
IJCLab was born in 2020 from the merger of five units (CSNSM, IMNC, IPN, LAL, LPT). The staff is made up of nearly 560 permanent (340 engineers, technicians and administrators and 220 researchers and teacher-researchers) and approximately 200 non-permanent including 120 doctoral students. The research themes of the laboratory are nuclear physics, high energy physics, theoretical physics, astroparticles, astrophysics and cosmology, particle accelerators, energy and the environment and health. IJCLab has very significant technical capacities (around 280 IT) in all the major fields required to design, develop / implement the experimental devices necessary for its scientific activity, as well as the design, development and use of instruments.
The doctoral student will conduct his or her research within the Astrophysics and Cosmo-chemistry (AC) team of the Astroparticle, Astrophysics, and Cosmology (A2C) division of the IJCLab laboratory. The team, which is based at a single site at the University of Paris-Saclay (in building 104 in the Orsay Valley), comprise seven permanent researchers and lecturers and one postdoctoral researcher.
As IJCLab is subjected to ZRR (Zone à Régime Restrictif) military regulation, hiring choices must be approved by the Haut Fonctionnaire Securité Défense (HFSD). Therefore, the date of employment written above should be understood as provisional, and may need to be delayed

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