报告题目:X-ray reflection spectra and lron line profile of the Accretion disk

报告人：刘诚

报告时间：2025年7月3日(周四)上午10:00-11:00

报告地点：浙江工业大学理学楼 A楼110会议室

摘要(Abstract): Asymmetric, broadened iron emission lines are a ubiquitous feature in the X-ray spectra of accreting compact objects, spanning stellar-mass black holes to active galactic nuclei. These lines arise when hard X-rays from a hot plasma irradiate the accretion disk, driving a combination of photo-ionization, fluorescence and Compton scattering-collectively referred to as “reflection” (though more precisely a process of reprocessing and re-emission). The iron Kα fluorescence line stands out prominently, set against a forest of emission lines and absorption edges from astrophysical abundant elements, as well as the broad “Compton hump" peaking at 20-30 keV. In this report,we first introduce the fundamental principles of reflection-spectroscopy modeling. We then concentrate on the most diagnostic feature-the iron-line profile-and describe how its shape encodes the spacetime geometry in which it is produced. Using the spectral-fitting package Xspec, we illustrate how to construct and fit models of the Fe K line under different relativistic assumptions. At last, we present real NuSTAR observations in which the modeled iron-line profile is detected, highlighting how these data constrain key physical parameters of the accretion flow and the central compact object.

报告人简介(Bio)：Cheng Liu is a Ph.D. candidate at the Tsung-Dao Lee Institute, Shanghai Jiao Tong University. He received his Master's degree in 2022 from the School of Science at Zhejiang University of Technology under the supervision of Professor Tao Zhu. His research focuses on black-hole astrophysics, in particular: GRMHD simulations of black-hole accretion disks, Modeling of X-ray reflection spectra, Time-domain observations and physical modeling of black-hole X-ray binaries. He has published over ten papers in international journals,including PRD and JCAP.

邀请人：朱涛