4–8 Aug 2025
The University of Hong Kong
Asia/Hong_Kong timezone

Probing Super-Eddington Accretion via X-ray Reflection: Insights from Simulations and Observations

7 Aug 2025, 11:20
20m
The University of Hong Kong

The University of Hong Kong

Speaker

Mr Zijian Zhang

Description

In this talk, I will explore the diagnostic power of X-ray reflection in unveiling the nature of super-Eddington accretion flows. In the first part, I present simulation results highlighting how reflection emission profiles are highly sensitive to wind kinematics and geometry. I show that incorporating multiple X-ray reflections within these winds can produce a distinctive double-peak line profile from face-on viewing angles. Furthermore, I demonstrate that the fluorescent Fe Kα line from super-Eddington flows occupies a parameter space distinct from standard thin disk accretion, offering a novel tool to identify and characterize black hole systems in super-Eddington states.
In the second part, I present a spectral analysis of EP240222a, an X-ray bright tidal disruption event (TDE) detected by the Einstein Probe. My modeling reveals a fast wind component with velocities reaching ~0.3c. This, alongside other observational signatures, supports the interpretation of EP240222a as a TDE from an intermediate-mass black hole that underwent super-Eddington accretion at its peak. Together, these findings underscore the potential of X-ray reflection studies to constrain extreme accretion phenomena in black hole systems.

Author

Co-author

Jane Dai (lixindai@hku.hk)

Presentation materials