| Summary: | <p>Einstein's theory of General Relativity has long been considered the standard theory of gravity, as it provides us with an extremely good description of how objects interact gravitationally at all scales. The Standard Model of cosmology, based on General Relativity, provides an excellent description of how astrophysical objects and matter interact. However, it requires the addition of two exotic ingredients: cold dark matter and dark energy, in order to correctly account for some observational phenomena, such as the accelerated expansion of the universe and the flat galaxy rotation curves that we observe. This has prompted the exploration of alternative theories of gravity, which can account for these observations without invoking the need for one or both of these exotic types of matter.</p>
<p>In this thesis we build different tools for testing such alternatives at large and small scales. The majority of the work focuses on testing beyond General Relativity models on large scales using cosmological probes. We derive theory-informed priors, find suitable forms for the time evolution of the functions parametrising specific sets of extensions to General Relativity, and put constraints on their parameters from cosmological data. In the last chapter we shift the focus to small scales, where we numerically confirm an expression for the drag force on a moving black hole. This result can be used to test a model of dark matter using the gravitational wave signal from a black hole binary merger. With the growing amount of gravitational wave data, testing alternative theories of gravity in this way is becoming an increasingly popular area of research. The future direction of this work is to apply the methods we commonly use for testing gravity on large scales, as described in this work, to test beyond General Relativity theories on small scales using gravitational wave data.</p>
|
|---|