269 Investigating the nature of Gamma-Ray Bursts with SVOM

Job title:

269 Investigating the nature of Gamma-Ray Bursts with SVOM

Company:

Centre National d’Etudes Spatiales

Job description

Gamma-Ray Bursts (GRBs) are powerful sources of gamma-rays lasting from a fraction of a second to a few hundreds of seconds, appearing randomly over the entire sky. These elusive phenomena have been discovered in the late ’60s of the last century, and have remained a mystery until in the late ’90s, thanks to the observations of the Italian-Dutch satellite BeppoSAX, the have been precisely located and associated with extragalactic transient sources, hosted in galaxies that span up to the earliest phases of the Universe, when the first structures formed.Nowadays we know that GRBs are divided in two categories reflecting two different channels of production. The first one is related to “collapsars”, i.e. the final stages of very massive stars (30-50 times the mass of the Sun). Indeed, following the gravitational collapse of these stars a black hole is created, and matter is accreted onto it. This matter is then ejected by powerful jets, and if these jets point towards the observer, we detect them as GRBs, and then as the associated afterglow (i.e. the emission following the GRB, in the X-ray, optical and radio band lasting hours to days).The second category of GRBs, the “mergers”, are believed to be associated with the merging of two compact objects (black holes or neutron stars), whose end product may be again a black hole, but also a highly magnetized neutron star, dubbed magnetar.SVOM (Space based astronomical Variable Object Monitor) is a space mission that has been developed in cooperation by the CNES and the Chinese National Space Administration (CNSA). It has been successfully launched on the 22nd of June of 2024, and it carries on board four instruments, two developed by China, and two developed by France under CNES responsibility. The payload is composed by two wide field-of-view and two narrow field-of-view instruments. The wide field instruments are ECLAIRs (a coded mask telescope operating in the 4-150 keV energy range) and GRM (a non-imaging spectrometer operating in the 25 keV – 5 MeV energy range). The narrow field-of-view instruments are the MXT (0.2-10 keV) and the VT (400-1000 nm). The space borne instruments are complemented on ground by three dedicated robotic telescopes, two of them located in China and operating in the optical band, and one issued by a French-Mexican collaboration, located in Mexico, and capable of observing the sky in the optical and near-infrared bands.SVOM nominal lifetime is 3 years, and a 2 year extension is possible. The PHD project deals with the use of SVOM data in order to study the characteristics of Gamma-Ray Bursts. In particular the PHD student will be part of the scientific team of the MXT telescope. The Microchannel X-ray telescope is an innovative instrument based on the coupling of “Lobster Eye” micropore X-ray optics to a state-of-the-art pnCCD with very good spectral capabilities. It has been developed by CNES, in close collaboration with CEA (Saclay), IJCLab (Orsay), MPE (Munich) and the University of Leicester.

The hosting laboratory is responsible for MXT Instrument Center, and has also the lead scientific role in the person of the PHD director.The successful PHD candidate will be asked to actively participate in the spectral and temporal analysis of the X-ray data collected by SVOM/MXT. These data shall then be compared to the broader data collected by the other SVOM instruments and international partners, in order to provide a physical interpretation of the GRB phenomenon. In particular, aspects such as the modeling of the energy injection during the afterglow phase will be addressed in order to better constrain the nature of the compact object at the origin of the relativistic collimated matter flux with the goal of understanding whether, we deal with black holes or magnetars in case of merger events. Merger type events are of particular interest, since they can also be detected through multi-messenger channels, such as gravitational waves. Binary neutron star merger can be detected by the new generation ground-based interferometers (LIGO/Virgo/Kagra) and the sky regions corresponding to their alerts can rapidly be scanned with SVOM/MXT in order to look for X-ray counterparts, even in absence of gamma-ray trigger signals.The successful PHD candidate will also act as a “Burst Advocate”, taking part in regular shift where she/he will be in charge of validating the SVOM alerts, and coordinating the follow-up from ground.For more Information about the topics and the co-financial partner (found by the lab !); contact Directeur de thèse –Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online before March 14th, 2025 Midnight Paris time !

Expected salary

Location

Gif-sur-Yvette, Essonne

Job date

Wed, 05 Feb 2025 05:23:29 GMT

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