Award Date

5-15-2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Committee Member

Bing Zhang

Second Committee Member

Zhaohuan Zhu

Third Committee Member

Ali Kheirandish

Fourth Committee Member

Pawan Kumar

Fifth Committee Member

Pengtao Sun

Number of Pages

534

Abstract

Fast Radio Bursts (FRBs) are bright radio bursts with the highest brightness temperatures in the radio sky. In this thesis, we investigate the trigger mechanisms, radiation mechanisms, and propagation effects of FRBs. Two general classes of coherent radiation mechanisms are considered in two categories: pulsar-like models invoking emission originating within the magnetar magnetosphere, and GRB-like models, which attribute the emission to relativistic magnetized shocks occurring far away from the central engine. We use the general observed properties (polarization features and spectra bandwidths) of repeating FRBs to constrain the physical conditions needed for these two mechanisms. We propose that crust quakes are invoked as a mechanism to trigger sudden transients in the magnetospheres of magnetars. Our simulations show that non-axisymmetric quakes will launch a mixture of Alfvén and fast magnetosonic waves into the magnetosphere. In this framework, FRBs are generated via coherent inverse Compton scattering (ICS) off low-frequency fast magnetosonic waves by bunches at a distance of a few hundred times the magnetar radius. We also investigate the polarization and spectra of the synchrotron maser model from three-dimensional particle-in-cell simulations. As large-amplitude FRBs are produced inside the magnetosphere, we compute the scattering cross section and the corresponding optical depth. In the strongly magnetized and quasi-parallel limits, the cross sections asymptotically recover the linear regime scalings and are strongly suppressed by relativistic particle motion, leading to optical depths well below unity. In addition, we explore long-period radio transients (LPRTs), a rapidly growing class of coherent radio sources with periods ranging from minutes to hours and relatively low brightness temperatures. We suggest that the radio emission properties of the system can be well explained within the framework of the unipolar inductor magnetic interaction model between the magnetized WD and the RD with low magnetization, with a relativistic version of electron cyclotron maser emission being the most likely radiation mechanism. We suggest that this mechanism can interpret at least some long-period radio transients. The short-period population of LPRTs is likely powered by other engines such as slow magnetars.

Controlled Subject

Radio astronomy; Magnetars; Magnetosphere

Disciplines

Astrophysics and Astronomy | Physical Sciences and Mathematics | Stars, Interstellar Medium and the Galaxy

File Format

PDF

File Size

24700 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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