2:00–3:00 pm
Please Join us:
Aurora Ireland's PhD Thesis Defense
Monday April 15, 2024 at 2:00 PM CDT
PHENOMENOLOGICAL MODEL BUILDING IN PARTICLE COSMOLOGY
The Standard Model of particle physics and the Lambda-CDM cosmological paradigm have been largely successful in describing the current state of the universe and how this came to be. And yet, we know both models to be incomplete, as there exist a great number of open questions left unaddressed by both. This thesis presents several model building efforts towards resolving these shortcomings in our current picture of particle cosmology. After reviewing the current state of affairs and the puzzles that persist, we turn to the events of the early universe. Focusing on two exceptionally promising probes – primordial black holes and their accompanying gravitational waves – we show how constraints on both can lead to inferences about inflation, the subsequent expansion history, and more. Next, we examine the cosmological phase transitions which may have occurred during this period, with particular emphasis on strongly first-order phase transitions accompanied by gravitational wave signatures. We address a major source of uncertainty in predictions of such phase transitions and present novel theoretical bounds on a model which is in principle capable of making the electroweak phase transition strongly first-order. Finally, we survey three mysteries of late-time cosmology, informed by present day observations and data. First, in the context of dark matter model building, we present a new scheme of asymmetric reheating which can reconcile dark sectors with light degrees of freedom with precision observables. Next, in light of recent observations of supermassive black holes at surprisingly high redshifts, we explore the possibility of supermassive black holes of a primordial origin. Finally, we present a novel mechanism for generating the primordial magnetic fields required to seed the cosmological magnetic fields observed today.
Committee Members:
Marcela Carena (Chair)
Dan Hooper
Gordan Krnjaic
David Schmitz
Carlos Wagner
Aurora is excited to be joining the Stanford Institute for Theoretical Physics as a Moore postdoctoral fellow in the fall.