Cosmology with primordial black holes

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Primordial black holes are a black hole which formed shortly after the big bang, long before stars existed. They are a potential relic from the initial conditions generated by inflation as well as a dark matter candidate.This PhD project will study the implications of observational tests of primordial black holes on models of inflation, including multiple-field models such as the curvaton or modulated reheating scenario, and constraints on the primordial power spectrum on small scales. To date we have precision measurements of the primordial power spectrum on large scales, which probe only about one tenth of the minimum expected duration of inflation. Whilst the current observational constraints are consistent with simple models of single-field inflation, new information from smaller scales may totally change our understanding of inflation as well as the subsequent reheating epoch, during which time primordial black hole formation could take place. The study will also account for primordial non-Gaussianities, which naturally have an important impact on the formation rate and initial clustering of primordial black holes, since their formation is a rare event relating to the tail of the probability density function. A complementary probe of the small-scale perturbations - which will also be studied are a stochastic background of gravitational waves - tiny ripples in space-time - which will be generated if the primordial power spectrum is sufficiently enhanced to produce primordial black holes, since scalar and tensor perturbations couple at second order in perturbation theory. This will provide an interesting overlap to gravitational wave searches by the current LIGO and future LISA experiments.