Generalized Perturbations in Modified Gravity and Dark Energy

1. Front Matter

   Pages i-xix

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2. Introduction to Gravitational Theories and Cosmology

   • Jonathan Pearson

   Pages 1-41

3. The Effective Action Formalism for Cosmological Perturbations

   • Jonathan Pearson

   Pages 43-58

4. Metric Only and First Order Scalar Field Theory

   • Jonathan Pearson

   Pages 59-80

5. High Derivative Theories

   • Jonathan Pearson

   Pages 81-126

6. Explicit Theories

   • Jonathan Pearson

   Pages 127-140

7. Connections to Massive Gravity

   • Jonathan Pearson

   Pages 141-159

8. Generalized Fluid Description

   • Jonathan Pearson

   Pages 161-174

9. Observational Signatures of Generalized Cosmological Perturbations

   • Jonathan Pearson

   Pages 175-192

10. Discussion and Final Remarks

    • Jonathan Pearson

    Pages 193-197

11. Back Matter

    Pages 199-200

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When predictions of Einstein's theory of General Relativity are compared against observations of our Universe, a huge inconsistency is found. The most popular fix for this inconsistency is to "invent" around 94% of the content of the universe: dark matter and dark energy. The dark energy is some exotic substance responsible for the apparent observed acceleration of the Universe. Another fix is to modify the theory of gravity: it is entirely plausible that Einstein's theory of General Relativity breaks down on cosmological scales, just as Newton's theory of gravity breaks down in the extreme gravitational field of the Sun. There are many alternative theories of gravity, each with the aim of describing observations of our Universe where General Relativity fails. Whether it is dark energy or some modified theory of gravity, it is clear that there is some "dark sector" in the Universe. In this thesis the author constructs a unifying framework for understanding the observational impact of general classes of dark sector theories, by formulating equations of state for the dark sector perturbations.

• Cosmology
• Equations of State for Perturbations
• General Relativity on Cosmological Scales
• Interfacing Theoretical and IObservational
• Introduction to Cosmology
• Modifications to Gravity
• Modified Gravity
• Testing Theories of Gravity with Observations

• Department of Mathematical Sciences, Durham University, Durham, United Kingdom

  Jonathan Pearson

Jonathan Pearson obtained his PhD in Theoretical Cosmology at Jodrell Bank Centre for Astrophysics, at the University of Manchester. His research topics include: domain wall network dynamics, constructing gauged cosmic vortons, inhomogeneous universes and constructing a formalism to use observational data to constrain modified gravity theories.

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