The formation of carbonaceous and silicate precursor molecules to astrophysical dust grains is investigated. Using density functional theory (DFT) in combination with global optimization techniques, the ground-state binding energies of dust precursors are determined. These results are employed in atomistic nucleation theory (ANT) to predict the critical size and nucleation...
Gamma ray bursts (GRBs) are short, intense pulses of gamma rays that emit radiation in a narrow beam. Unless the beam is oriented towards the observer, it is often difficult to resolve the bursts against the diffuse gamma ray background (DGRB). The DGRB is a measured source of gamma rays...
The binding energies of n < 100 carbon clusters are calculated using the ab initio density functional theory code
Quantum Espresso. Carbon cluster geometries are determined using several levels of classical techniques and further
refined using density functional theory. The resulting energies are used to compute the work of cluster...
During AY 2009/10 OSU Libraries’ Research and Innovative Services Department (RIS) conducted a pilot project on “environmental scanning.” One of our goals for the year is to develop a process to investigate emerging trends based on a topic and disseminate our findings. Initially we each scanned a segment of the...
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American Astrophysical Society’s
Astronomical Journal and the product is named AJ Compilations. The
In this dissertation, I present electronic spectra of a few polycyclic aromatic hydrocarbons (PAHs): tetracene, pentacene, pyrene, benzo[g,h,i]perylene and benzo[a]pyrene using resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. The work of tetracene and pentacene also combine a laser desorption source with a ZEKE spectrometer, demonstrating...
In this dissertation, I describe spectroscopic studies of jet-cooled polycyclic aromatic hydrocarbons (PAH) and one nitrogen substituted PAH (PANH) using pulsed field zero kinetic energy (ZEKE) photoelectron spectroscopy and resonantly enhanced multiphoton ionization (REMPI) spectroscopy. Recently, there has been a demand for far-infrared (FIR) spectral information of astrophysically relevant molecules...
Gravitational waves (GWs) are disturbances in spacetime that can be caused by events such as black hole mergers and supernovae, as well as continuous sources such as binary star systems. GWs offer a new avenue of astrophysical research and can reveal information about the early universe. GW detection can be...
We report zero kinetic energy (ZEKE) photoelectron spectroscopy of benzo[a]pyrene (BaP) via resonantly enhanced multiphoton ionization (REMPI). Our analysis concentrates on the vibrational modes of the first excited state (S₁) and those of the ground cationic state (D₀). Similar to pyrene, another peri-condensed polycyclic aromatic hydrocarbon we have investigated, the...
The discovery of GW170817 provided the first empirical evidence that merging binary neutron star systems are both progenitors of short gamma-ray bursts, as well as the primary sites of the nucleosynthetic rapid-neutron capture process. Initially detected as gravitational wave (GW) and gamma-ray burst (GRB) triggers, GW170817 was well-localized and follow-up...
Short gamma-ray bursts (GRBs) are explosions of cosmic origins believed to be associated with the merger of two compact objects, either two neutron stars or a neutron star and a black hole (BH). The presence of at least one neutron star has long been thought to be an essential element...
From the earliest English colonization to the present day, there
has been interest in astronomy in this country. The purpose of this
thesis is to show how the science of astronomy developed in America
from the earliest observations by educated colonists using imported
instruments and publishing in European journals, to...
Computational simulations of disks are becoming an important tool to predict the the evolution of protostars and disks to better understand the formation of planets. Past research has shown that the evolution of disks and their protostar can be altered through the interaction between gravity and hydrodynamic instabilities. We perform...
Core-collapse supernovae (CCSNe) are considered to be important contributors to the primitive dust enrichment of the interstellar medium in the high-redshift universe. Theoretical models of dust formation in stellar explosions have so far provided controversial results and a generally poor fit to the observations of dust formation in local supernovae....
One of the most important unresolved issues in gamma-ray burst (GRB) physics is the origin of the prompt gamma-ray spectrum. Its general non-thermal character and the softness in the X-ray band remain unexplained. We tackle these issues by performing Monte Carlo simulations of radiation-matter interactions in a scattering dominated photon-lepton...
Studying the evolution of the Milky Way galaxy helps us understand our place in the Universe. Early evolution of the Galaxy can effectively be studied by observing stars with low metallicity values since they are the oldest stars still visible. Due to the formation of the Galaxy, the oldest stars...
We present an analysis of the relationship between spectral lag and luminosity in time-resolved segments of long gamma-ray bursts detected by BATSE, an experiment aboard the Compton Gamma Ray Observatory satellite. For full bursts, there is a well-established correlation between the lag, which is easily computed, and the total burst...
We study the late-time (t > 0.5 days) X-ray afterglows of nearby (z < 0.5) long gamma-ray bursts (GRBs) with Swift and identify a population of explosions with slowly decaying, super-soft (photon index Γx > 3) X-ray
emission that is inconsistent with forward shock synchrotron radiation associated with the afterglow....