Physics & Astronomy ETDs

Publication Date

Fall 12-10-2019


In the standard thermal history of the Universe, the energy density is dominated by radiation throughout the postinflationary era, until matter-radiation equality after big bang nucleosynthesis (BBN). However, we currently do not have any observational probes of the pre-BBN period, and radiation domination (RD) is therefore an assumption. Generic early Universe models predict the presence of additional components in the postinflationary Universe which can lead to periods of nonstandard evolution before the onset of BBN. A prominent example of such a period is a phase of early matter domination (EMD) in which the Universe undergoes matter-dominated expansion for a time, before transitioning to the standard RD phase. The pre-BBN era is additionally the natural time for the production of dark matter (DM), which is a necessary component for the later evolution of the Universe. Furthermore, the production of DM is highly sensitive to the thermal history of the Universe, and can therefore serve as a probe of the pre-BBN era as ongoing and future searches continue to explore the DM parameter space. As a consequence of current searches, the prevailing scenario, in which weakly interacting massive particles (WIMPs) are thermally produced in the standard thermal history, is coming under increasing pressure. In this dissertation, we will study DM production beyond the thermal WIMP paradigm, focusing on the effects of EMD eras in the pre-BBN Universe.

Degree Name


Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Rouzbeh Allahverdi

Second Committee Member

Dinesh Loomba

Third Committee Member

James Dent

Fourth Committee Member

Huaiyu Duan

Fifth Committee Member

Akimasa Miyake




Cosmology, Dark Matter, Early Universe, Thermal History of the Universe, Early Matter Domination, Phenomenology

Document Type