SEMINÁRIO DO DEPARTAMENTO DE ASTRONOMIA
General-relativistic magnetar magnetospheres in 3D with physics-informed neural networks
a talk by Petros Stefanou (IAG-USP/Brasil) - In-Person
Abstract:
"Magnetars exhibit highly variable X-ray activity of magnetospheric origin, driven by twisted magnetic fields that undergo severe reconfiguration upon reaching a twist limit. The energy stored in the magnetic field is subsequently released producing in the observed emission. In the vicinity of compact objects like neutron stars a fully general-relativistic treatment is needed to accurately estimate the available energy. We present the first three-dimensional general-relativistic models of twisted magnetar magnetospheres exploring a range of magnetic field strengths, surface currents and stellar compactness. The force-free equations in curved spacetime are solved using physics-informed neural networks, a method that enables us to extend beyond the current state of the art and investigate more extreme configurations than previously possible. Our results show that stable configurations contain only a limited reservoir of free magnetic energy, with at most ≈ 5% excess over the potential state in fully 3D configurations with localized currents, which goes up to ≈ 30% in the case of global axisymmetric twists. We examine the implications of these findings for the observed X-ray bursting activity of magnetars and discuss the plausibility of observable gravitational wave emission of magnetospheric origin from magnetars."
Short-Bio:
I am a theoretical astrophysicist and a Postdoctoral Researcher at IAG. Previously I was a Postoctoral Researcher at the University of Alicante. I hold a PhD in Astrophysics from the University of Valencia (2024) and an M.Sc. in Astrophysics from the National and Kapodistrian University of Athens (2019). My research focuses on modeling neutron star magnetospheres and applying machine learning to theoretical astrophysics.
Google Meet: https://meet.google.com/pcw-gmem-jyi
Link da transmissão: https://www.youtube.com/c/AstronomiaIAGUSP/live