# Charles MARTEAU - accessit of the DANIEL GUINIER 2021 prize of the French Physical Society

Charles Marteau is an alumnus of the École Normale Supérieure de Cachan. He studied theoretical physics at the master's degree of the École Normale Supérieure de Paris and fundamental mathematics at the master's degree of Sorbonne University. He joined the string theory group in fall 2017, as a PhD student under the supervision of Marios Petropoulos, on the topic Boundary structures and holographic fluids in gravity.

The arrival of Charles Marteau in the team coincided with the launching of a new research area, holographic correspondence gravity / gauge theory in asymptotically flat space-time, in which another student, Luca Ciambelli, was involved. Together, they clarified the structure underlying the fluid/gravity version of flat holography, namely Carrollian fluid dynamics, an ultra-relativistic version of hydrodynamics. Thanks to this fruitful collaboration, Charles Marteau pursued his thesis in many directions. The main advances of his work can be summarized as follows: (i) the extension of the fluid/gravity correspondence to the flat case which required the ab initio design of Carrollian hydrodynamics; (ii) an exhaustive investigation of three-dimensional gravity and its applications in two-dimensional fluids; (iii) finally the application of Carrollian concepts to the study of the black-hole horizon dynamics.

During his PhD time, Charles Marteau made several long visits abroad, in Europe and in the US, during which he developed his own collaborations with other doctoral and post-doctoral fellows. The extent of the work accomplished as well as his independence as a young researcher can be measured in his publication list: nine articles, four of which were written without his thesis director and signed with a young collaborator. His dissertation is a collection of his first seven papers, put in perspective by an introductory text which allows to set up the framework and to introduce the general notions of asymptotic symmetries and Carrollian geometry.

Charles Marteau is currently a post-doctoral researcher at the University of British Columbia in Vancouver, where he continues his activities in the group of Gordon Semenoff.