Séminaire IPAG

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(GR)MHD modeling of accreting compact objects: numerical challenges and recent developments

jeudi 30 mars 2023 - 11h00

Matheo Bugli - Université de Turin
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Accretion onto compact objects is the most efficient mechanism in the Universe to convert gravitational energy into high-energy radiation and relativistic particles that we can detect from Earth. Numerical fluid models (and in particular, magnetohydrodynamics, MHD) represent a fundamental tool to investigate the large-scale behaviour of relativistic plasmas orbiting a central compact object, as they can explore the intimate connection between the accretion and ejection of matter and energy via powerful outflows launched by a disk-compact object system. However, such approach can present several shortcomings, such as inaccurate dissipation properties of the plasma, lack of kinetic effects and a general difficulty in self-consistently describing a collisionless plasma at the smaller scales. In this seminar I will review some of the most recent attempts at surpassing the standard (general relativistic) MHD framework by including new physical ingredients such as mean-field dynamo processes, explicit turbulent resistivity and effective magnetic dissipation from reconnection layers. I will show how these processes can help bridging the spatial and temporal scale gap that separates standard PIC and GRMHD models and lead to a more consistent description of the fundamental dynamics of accreting compact objects. Finally, I will present a brand-new high-order numerical scheme that could significantly improve the accuracy of current numerical simulations of astrophysical plasmas

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Hôtes : Benoit Cerutti

Salle Manuel Forestini, 414 rue de la piscine, 38400 Saint Martin d'Hères