With the support of a post-doctoral fellowship from the French Space Agency, starting from February 1994, I went to the Harvard Smithsonian Center for Astrophysics (CFA) in the High Energy Astrophysics Division working mostly with Pr. Josh Grindlay, but also with Pr. Ramesh Narayan and Dr Jeffrey McClintock.Finally, in May 1996, I obtained a permanent researcher position at CNRS. I left CFA in December 1996.

Since January 1997, I am working in the high-energy group of CESR. In December 2000, I passed my "Habilitation", to get the degree of Docteur Es Science. From 2000 to 2004, I was the secretary of the French Astronomical Society (Société Française d'Astronomie et d'Astrophysique) with successively Dr. Suzy Collin and Dr. Francoise Combes acting as President. With the appointment of Pr. Giovanni Bignami in 2003 as the Director of CESR (since January 2003), I am getting more and more involved in the administration of the research conducted at CESR, elected as the Chairman of the Technical and Science Council of the institute.

In 2003, I was awarded a Médaille de Bronze (bronze medal award for young researchers) of CNRS. In June 2004, together with colleagues at the Observatoire Midi-Pyrénées, we started the association called "Les étoiles brillent pour tous" (Stars shine for everyone), whose goal is to bring Science in places where in general it is not presented and discussed (jails, hospitals,...).

In September 2004, I was elected Vice-President of the Société Française d'Astronomie and Astrophysique, with Dr. Fabienne Casoli, acting as the President. In January 2005, I was selected member of the European Space Agency Astronomy Working Group (ESA/AWG), as the French representative. I then joined the Astronomy Working Group of the French Space Agency (CNES) and its Science Advisory Group.

In May 2005, I was promoted Directeur de Recherches at CNRS. In September 2006, I was elected President of the Société Française d'Astronomie and Astrophysique. In December 2006, I was appointed by the French Space Agency, as the Chairman of the Astronomy Working Group. Between 2005 and 2007, I was appointed by the European Space Agency, member of the Astronomy Working Group.

In December 2007, I was appointed by the European Space Agency (ESA) a member of the XEUS Study Team, to become in September 2008, member of the International X-ray Obsevatory Study Coordination Group. During the study phase, I am acting as the Instrument Study Scientist for the High-Time Resolution Spectrometer.

Together with Kirpal Nandra, we submitted a M3 mission proposal, called GRAVITAS, in response to the ESA call for the Cosmic Vision 2015-2025 program.

Since January 2011, I am the head of the Galaxy, High Energy Astrophysics and Cosmology group of the newly founded Institute of Research in Astrophysics and Planetology of Toulouse. For my group, I did coordinate the proposal for «Laboratoire d’excellence» called OCEVU, together with Marseille (CPPM, LAM) and Montpelier (L2C, LUPM).

I am a member of the international science advisory committee of the Space Research Organization of the Netherlands.

In 2011, I was a member of the Athena Science Study Team. The study was terminated by the non selection of Athena. Since 2011, I am also a member of the LOFT Science study team. LOFT is an X-ray Timing mission, proposed as a candidate for the third med-size mission of the Cosmic Vision program.

Since March 2012, I am member of the Executive Committee of the Cluster Institute of Excellence, called OCEVU, as the head of the Galaxy, High Energy Astrophysics and Cosmology group of the Institute of Research in Astrophysics and Planetology of Toulouse.

In September 2013, for the association « Les étoiles brillent pour tous» I was awarded the price «Le goût des sciences 2013» from Ms Geneviève Fioraso, Minister of Education and Research.

In November 2013, I was promoted Directeur de Recherches Première classe at CNRS, and about the same day, the Hot and Energetic Universe science theme was selected by ESA as the science to be covered by its next large mission. The Athena mission was proposed to ESA in early 2014. After 17 years of attempts, Athena was finally selected by the ESA SPC on June 27th, 2014. I am now acting as the PI of the X-ray Integral Field Unit instrument, one of the two science payload elements of the Athena mission. Athena should be launched at the end of the next decade. The X-IFU development will be managed by the French Space Agency.

In december 2015, I end my 5 year term as the head of the Galaxy, High-energy Astrophysics and Cosmology group of IRAP. I shared the post with Roser Pello.

Since June 2014, my professional career is entirely devoted to the development of the Athena X-IFU. I am a member of the Athena Science Study Team appointed by ESA. I keep some collaborations with colleagues, mostly in the field of ultra-luminous X-ray sources and X-ray binaries.