Sherpas

Astrophysical environments give access to conditions that cannot be realised on Earth. The team is mainly interested in the dynamics, the kinetics and the radiation from astrophysical plasmas. Which processes are responsible for transporting matter in accretion discs ? How is part of the material ejected in winds and jets ? Why are some of the particles accelerated to relativistic energies ?

Research topics

The SHERPAS team (Sources of High Energy, Relativistic Plasmas, Accretion Structures) studies accretion-ejection processes, particle acceleration, high-energy phenomena in protoplanetary discs, compact objects, the Galactic centre, active galactic nuclei. Its main goals are: understanding the dynamics of magnetised plasmas around young stellar objects, black holes and neutron stars ; the theory of particle acceleration at shocks and at magnetic reconnection sites ; the observation and modelling of high-energy radiation associated with compact objects.

The team develops models and numerical codes to study these phenomena, using high-performance computing to e.g. characterise magneto-hydrodynamical turbulence in accretion discs (SNOOPY, IDEFIX codes) or identify the sites of non-thermal emission in tenuous magnetised plasmas around pulsars or black holes (ZELTRON code). The team routinely uses data from space-based X-ray and gamma-ray observatories such as XMM, NuSTAR, Chandra, IXPE, Fermi, or INTEGRAL, and is active in the preparation of future observatories such as CTA, SVOM, Athena. The team also has an expertise in the application to astrophysics of sophisticated statistical methods (classification, cladistics).

keywords

Accretion, accretion disks; acceleration of particles; plasmas; magnetohydrodynamics; magnetic reconnection; instabilities; radiation mechanisms; relativistic processes; shock waves; turbulence; statistical methods; close binaries; black holes; neutron stars; protostars; pulsars; cosmic rays; jets and outflows; Galactic center; active galaxies