Stars, Interstellar Medium and the Galaxy Commons^™

Study Of 134in Beta-Delayed Neutron Emission And Development Of A New Generation Neutron Detector, Joseph Heideman

Doctoral Dissertations

Beta-delayed neutron emission in very neutron-rich nuclei plays an essential role in nuclear structure and the understanding of the astrophysical r-process. A complete description of this process requires knowledge of both steps, beta decay and neutron emission. A leading theory poses the intermediate daughter nucleus to behave as a compound nucleus. The conditions for beta-delayed neutron emission of 134In are not well described by the assumptions in the neutron pandemonium hypothesis, therein providing a unique case to this process due to the proximity to 132Sn. Single-particle states in 133Sn obvserved after neutron emission have dissimilar shell occupancy compared to neutron-hole …

Observational Studies Of Fragmentation In Molecular Clouds, Riwaj Pokhrel

Doctoral Dissertations

In this dissertation, I explore fragmentation physics in multiple scales in nearby molecular clouds and discuss some implications of fragmentation for cloud structure formation and star formation, primarily by analyzing multi-wavelength observations of dust emission. First, I tested the complete thermal and combined thermal and nonthermal support mechanisms that balance gravitational contraction at multiple scales in the Perseus molecular cloud. I found that the observed multiscale structures in Perseus are consistent with an inefficient thermal Jeans fragmentation, where the Jeans efficiency increases from the largest scale ($\gtrsim$10s of pc) to the smallest scale ($\sim$10s of AU). Next, I studied the …

Astrophysical Accretion And Feedback: The Bayesian Linchpin Of Theory And Observation, Shawn Roberts

Doctoral Dissertations

Despite being a major pillar of galaxy evolution, galactic feedback from stars and supermassive black holes (SMBHs) is subject to very little observational constraint. This is particularly true of the hot component, as viewed in X-rays. Yet, the hot component is directly linked to much of the energetic feedback released from these compact objects. X-ray observations suffer from several challenges that make placing this constraint a difficult task. In the face of considerable model uncertainty, these challenges underscore the need for novel X-ray data analysis techniques. In this dissertation, I seek to lend a unique perspective to X-ray data analysis …

The Cosmic Web, And The Role Of Environment In Galaxy Evolution, Ryan Cybulski

Doctoral Dissertations

The Universe, on extra-galactic scales, is composed of a vast network of structures dubbed the “cosmic web”. One of the most fundamental discoveries about the evolution of galaxies is that their properties have a dependence on their location relative to this cosmic web (i.e., their environment). However, detailed studies of the environmental dependence on galaxy evolution have been extremely challenging due to the inherent complexity of the structures on the largest scales, a plethora of techniques being used to try to map the cosmic web, and other confounding factors, such as the masses of galaxies, that also affect their evolution. …

The Study Of Nuclear Structure Of Neutron-Rich 81ge And Its Contribution In The R-Process Via The Neutron Transfer Reaction 80ge(D,P), Sunghoon Ahn

Doctoral Dissertations

The study of low-lying levels of nuclei near closed shells not only elucidates the evolution of nuclear shell structure far from stability, but also affects estimates of heavy element nucleosynthesis in supernova explosions. Especially, the properties of the low-lying levels in ⁸¹Ge[Germanium 81] are important because the sensitivity study of the r-process pointed out that the properties of the nucleus can affect the final bundance pattern. Also, the spins and parities measurements of the states are essential to understand the shape coexistence in odd-mass N = 49 isotones.

This work describes the study of the odd-mass N = …