【6.9; Seminar】2025年粒子天体物理全国重点实验室系列学术报告 #12：Magnetospheric Wave Emission from Magnetar Crust Quakes in Fast Radio Bursts

时间/Time: 6月9日周一下午2:00/Monday, June 9, 2:00 p.m.

地点/Location: 主楼415会议室/Meeting Room 415, Main Building

报告人/Speaker: Yuanhong Qu (University of Nevada, Las Vegas)

题目/Title: Magnetospheric Wave Emission from Magnetar Crust Quakes in Fast Radio Bursts

主持人/Host: 熊少林/Shaolin Xiong

摘要/Abstract:

In this talk, I will present generic constraints from observations on intrinsic

radiation mechanisms of FRBs. I will show that crust quakes of magnetars are vital for all kinds of wave modes in the magnetosphere. The elastic waves are produced by the incompressible shear perturbation in the magnetar crust and propagate perpendicular to the surface. Although the elastic waves in the crust are effectively incompressible, they directly couple to both compressible (fast magnetosonic) and incompressible (Alfven) waves in the magnetosphere. The two MHD waves are typically in the kilohertz band generated from magnetar crust quakes. Fast magnetosonic waves can be generated when the background magnetic field is not completely perpendicular to the surface. I will present 3D elasto-dynamics simulations of the entire crust and find that both fast magnetosonic waves and Alfven waves can be produced and both waves could have a comparable energy ratio. The star quake and associated magnetospheric wave emission are rapidly damped by magnetic coupling to the core. The quake is damped on a timescale ~ ms. consistent with the observed magnetar burst durations. The results will be important for providing possible trigger mechanisms for generating FRBs and I will review some possible radiation mechanisms triggered by the two MHD waves. Finally, I will show that FRBs are likely generated via coherent inverse Compton scattering off low-frequency fast magnetosonic waves by bunches at a distance of a few hundred times the magnetar radius and discuss the observational implications including high degrees of linear and circular polarization, narrow spectra as observed in many bursts from repeating FRB sources.

个人简介/Biography:

Yuanhong Qu is the fourth year PhD student in University of Nevada, Las Vegas, working with Bing Zhang. Yuanhong's research focuses on understanding the underlying physics of high energy phenomena in the universe, including fast radio bursts, long-period radio transients.