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The origin of cosmic rays (CRs) remains an open question. The CR spectrum is characterized by two significant breaks: the knee at ~3 PeV (PeV=1e15 eV) and the ankle at ~3 EeV (EeV=1e18 eV). It is widely accepted that ultra-high-energy cosmic rays (UHECRs) above the ankle originate from extragalactic sources, with the transition energy between galactic and extragalactic components lying between the knee and the ankle. Observations suggest that Centaurus A could be a major source of UHECR anisotropies and the hotspot, supporting that radio galaxies are sources of UHECRs. Recent gamma-ray observation of microquasars suggests microquasar can accelerate particle efficiently at least up to several PeV. In this talk, I’ll present a framework based on turbulent acceleration in velocity shearing jet, where both multi-wavelength observation of radio galaxies and UHECR observations can be explained. Our relativistic magnetohydrodynamic and particle-in-cell (RMHD-PIC) simulations demonstrate that CRs can be accelerated close to the Hillas limit. With the derived jet parameters, we found that Centaurus A type sources can accelerated CR protons to several EeV while Cygnus A type sources can accelerate protons to above 10 EeV. Furthermore, similar acceleration can take place in galactic super-accreting microquasars, where around 10 sources can account for the CR flux between the knee and the ankle.

BIO

Jieshuang Wang obtained his PhD in 2018 in Nanjing University. After completing his PhD, he joined the TDLI as a postdoctoral fellow. From 2022 to 2024, he was awarded an Alexander von Humboldt Fellowship and worked at the Max Planck Institute for Nuclear Physics in Germany. Since June 2024, he has been a postdoctoral researcher at the Max Planck Institute for Plasma Physics in Germany. His research interests lie in high-energy astrophysics and plasma astrophysics, focusing on extreme phenomena powered by compact objects such as accreting black holes, neutron star binaries, and magnetars. He investigates dynamics, particle acceleration, and multi-messenger radiation through both analytical modeling and numerical simulations. His recent research focuses on the role of astrophysical jets in the origin of cosmic rays and multi-messenger signals. He has authored more than 50 publications and has received over 3000 citations.

Host: Xuening Bai