The proposed PhD aims at calibrating the flight model of SVOM/ECLAIRs and studying its performance for the detection of hard X-ray transients in the local universe (z<0.2 or DL<1Gpc). The interest for these phenomena has recently been strengthened by the discovery of a short gamma-ray burst GRB 170817 due to the merging of two neutrons stars that radiated copious gravitational waves (Abbott et al. 2017a,b).
ECLAIRs is the coded mask hard X-ray imager of SVOM (Space-based Variable astronomical Objects Monitor), a Chinese-French space mission due for launch in 2021 (Wei et al. 2016). The instrument relies on a large detection plane (~1000 cm2) made of 6400 CdTe detectors, that looks at the hard X-ray sky through a coded mask (cf. Godet et al. 2014). The mask projects its shadow on the detectors, permitting the reconstruction of sky images. The detection plane of ECLAIRs is currently under construction at IRAP, and the construction of the flight model will be finished few weeks after the start of the PhD, allowing detailed measurements of the energy and angular response of the 6400 detectors. After its completion at IRAP, the detection plane will be integrated into the flight model of the instrument in CNES, and delivered to China for a launch at the end of 2021.
As a member of the science team in charge of the instrument, the student is expected to significantly contribute to the detailed characterization of the detectors. This work will be based on measurements performed with the detection plane installed in a vacuum chamber, illuminated with various X-ray sources (the student will not manipulate X-ray sources). The work will involve detailed analyses of the measurements, the simulation of the response of the detection plane, and the construction of the responses matrices and configuration tables to be used in flight. The student is also expected to participate to the commissioning of the instrument after launch, thus having the unique opportunity to work on the instrument characterization before and after its launch into space, during two crucial phases of instrument characterization.
In a second phase of the PhD, the student will use the response matrices to evaluate the sensitivity of SVOM/ECLAIRs to selected populations of local X-ray transients (typically within 1 Gpc, see http://www.atlasoftheuniverse.com/index.html). These populations are of high interest since they are within reach of gravitational waves detectors and neutrino detectors. They include:
- GRBs similar to the short GRB 170817A associated with GW170817, a burst of gravitational waves detected by the LVC collaboration (Abbott et al. 2017a,b).
- Classical short GRBs due to the coalescence of two neutron stars (Berger 2014).
- X-ray flashes (Barraud et al. 2003, Sakamoto et al. 2004).
- Sub-luminous GRBs like GRB 980425A (Galama et al. 1998), which can be associated with supernovae or not, and whose origin remains mysterious.
- SN shock breakout bursts, produced when the exploding core of a massive star impacts the star’s atmosphere (Campana et al. 2006).
- Tidal disruption events due to the disruption of a star coming too close to a supermassive black hole in a nearby galaxy (Bloom et al. 2011, Burrows et al. 2011).
The student will estimate the sensitivity of SVOM/ECLAIRs to these events and evaluate their respective rates of detection, specifying the role of SVOM for the studies of cosmic explosions in the local universe. Eventually she/he could propose optimized strategies for the detection of selected populations.
The PhD student must have some knowledge of astrophysics, instrumentation and detectors, and be familiar with programming in Python. During the PhD, the student will acquire a good knowledge of high-energy instrumentation and the constraints faced by space instruments, as well as a detailed understanding of high-energy cosmic phenomena. This PhD will give to the selected student the opportunity to work in a very dynamic international collaboration. After this PhD the student will be in a good position to apply for a postdoc in Astronomy or to look for an engineer position in space industry.
Candidate with a master's degree in Astrophysics or Physics or from an engineering school with a specialization in physics. The candidate must have some knowledge of astrophysics, instrumentation and detectors, and be familiar with programming in Python
To apply, we invite you to contact the PhD/research supervisor and fill, with him/her, the co-financing part of the online application form (Reply to the offer) by April 1st, 2019.