|Ph.D Student||Zacharia Myers|
|Subject||Searching for Dark Matter in and beyond our Evolving Galaxy|
|Department||Department of Physics||Supervisor||Full Professor Nusser Adi|
|Full Thesis text|
Since its inception, this thesis has progressed to incorporate various astrophysical topics. Our original intention was to focus on potentially novel ways of indirectly detecting Dark Matter (DM) including the possibility of detecting a signature of DM from the sun and other stars in the galactic disk (details to follow), and from this point our focus shifted more toward the contents of the stars that could produce such a signal. Once we had thoroughly exhausted the topic of indirect DM signatures from the stars, we shifted our focus onto the element abundances of stars, with a primary focus on the issues surrounding the measured abundances of Lithium. This thesis is to be read in two parts. The first part will be devoted to selected topics in DM; the second part will be devoted to addressing the various issues regarding stellar Lithium abundances.
The first part of this thesis begins with a background chapter where we summarize some of the most promising strategies and techniques to probe the nature of DM, such as direct detection experiments designed to observe the elastic scattering of DM particles with nuclei, indirect detection experiments which hope to detect the annihilation or decay products of DM such as photons, neutrinos, and antimatter, and the ”creation” of DM from high energy colliders. We also describe how the by-products of DM annihilation or decay could be used to explain recent astrophysical data anomalies. We proceed to check specific claims made from recent models of DM decay that could fit these recent data anomalies by ensuring that they are consistent with measured bounds of gamma rays and neutrinos (Chapter 3). We devote Chapters 4 and 5 to present our own novel predictions of indirect signatures of DM through its annihilation by-products, primarily through neutrinos from the galactic stellar disk and from 21 cm radiation from HI at high redshifts.
In Part II of this thesis, we present a novel solution to one of the many aspects of the Lithium problems in stars via an early Galactic starburst as a source of intense supernovae (SNe) and cosmic rays (CRs), which interact (spallate) with the interstellar medium (ISM) to create 6 Li and therefore can explain the overabundance and plateau of 6 Li observed in stars at low metallicities. We also review and summarize various models of non-standard stellar evolution and their relevance to the Lithium plateau(s) regarding Lithium depletion in stars.