Experimental gravity with electromagnetic and gravitational waves

Cardenas-Avendano, Alejandro

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Description

Title

Experimental gravity with electromagnetic and gravitational waves

Author(s)

Cardenas-Avendano, Alejandro

Issue Date

2021-04-19

Director of Research (if dissertation) or Advisor (if thesis)

Yunes, Nicolas

Doctoral Committee Chair(s)

Gammie, Charles F

Committee Member(s)

• Narayan, Gautham
• Witek, Helvi

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• black holes
• gravitational waves
• general relativity
• x-rays
• chaos
• experimental gravity
• accretion disks

Abstract

Electromagnetic and gravitational observations can be used to elucidate the nature of compact objects and the fundamental properties of the material in their vicinity. Our ability to extract information about the underlying physics from observations of both electromagnetic and gravitational spectra depends on our understanding of the gravity theory that describes the geometry around these compact objects. For electromagnetic observations, we must also understand the complex astrophysics that produces the observed radiation. In this dissertation, we describe our efforts to constrain and detect deviations from general relativity using: the electromagnetic radiation emitted by an accretion disk around a black hole; the gravitational waves produced when comparable-mass black holes collide; and we have also studied chaotic signatures that could appear when a small compact object falls into a supermassive object during an extreme mass-ratio inspiral. Our analyses combined relativistic ray-tracing and Markov Chain Monte Carlo sampling techniques, as well as analytical and numerical calculations of the motion of particles. We found that even when a simple astrophysical model for the accretion disk is assumed a priori, the uncertainties and covariances between the parameters of the model and the parameters that control a deviation from general relativity make tests of general relativity very challenging when applied to accretion disk spectrum observations. We also found that current gravitational wave observations place constraints on metric deformation parameters that are more stringent than what can be achieved with current X-ray instruments. Based on our numerical findings when studying extreme mass-ratio inspirals, we conjecture that the geodesics of the as-of-yet unknown exact solution for spinning black holes in a dynamical Chern-Simons theory is integrable. Consequently, we predict the existence a fourth integral of motion associated with the exact solution. The work presented in this thesis advances the development of both analytic calculations and computational simulations to test our understanding of gravity’s fundamental properties with electromagnetic and gravitational waves.

Graduation Semester

2021-05

Type of Resource

Thesis

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Copyright and License Information

Copyright 2021 Alejandro Cardenas-Avendano

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