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  • The Formation of Astrophysical Dust

    Creator:
    Mauney, Christopher M.
    Abstract:
    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...
    Resource Type:
    Dissertation
    Full Text:
    of Astrophysical Dust Abstract approved: Davide Lazzati The formation of carbonaceous and silicate

  • Off-Axis Gamma Ray Burst Contribution to the Diffuse Gamma Ray Background in the 100-600 keV Range

    Creator:
    Hodges, Isaac
    Abstract:
    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...
    Resource Type:
    Honors College Thesis
    Full Text:
    . Tueller. Cosmic X-Ray Back- ground and Earth Albedo Spectra with Swift BAT. The Astrophysical Journal, 689

  • Formation and Properties of Astrophysical Carbonaceous Dust. I. Ab-initio Calculations of the Configuration and Binding Energies of Small Carbon Clusters

    Creator:
    Mauney, Christopher, Nardelli, Marco Buongiorno, and Lazzati, Davide
    Abstract:
    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...
    Resource Type:
    Article
    Full Text:
    and binding energies of small carbon clusters. Astrophysical Journal, 800(1), 30. doi:10.1088/0004

  • Zero kinetic energy photoelectron spectroscopy of polycyclic aromatic hydrocarbons

    Creator:
    Zhang, Jie
    Abstract:
    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...
    Resource Type:
    Dissertation
    Full Text:
    study is to offer a database for astrophysical modeling, in terms of both direct line identification

  • Zero Kinetic Energy Photoelectron Spectroscopy of Polycyclic Aromatic Hydrocarbons

    Creator:
    Harthcock, Colin
    Abstract:
    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...
    Resource Type:
    Dissertation
    Full Text:
    astrophysical environment, we have initiated a systematic study of polycyclic aromatic hydrocarbons

  • Zero kinetic energy photoelectron spectroscopy of jet cooled benzo[a]pyrene from resonantly enhanced multiphoton ionization

    Creator:
    Zhang, Jie, Harthcock, Colin, Han, Fangyuan, and Kong, Wei
    Abstract:
    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...
    Resource Type:
    Article
    Full Text:
    THE JOURNAL OF CHEMICAL PHYSICS 135, 244306 (2011) Zero kinetic

  • Short Gamma-Ray Bursts from the Merger of Two Black Holes

    Creator:
    Perna, Rosalba, Lazzati, Davide, and Giacomazzo, Bruno
    Abstract:
    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...
    Resource Type:
    Article
    Full Text:
    , a BH is generally expected to be formed The Astrophysical Journal Letters, 821:L18 (6pp), 2016

  • Beating Modes in Protostellar Disks

    Creator:
    Varga, Attila V.
    Abstract:
    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...
    Resource Type:
    Undergraduate Thesis
    Full Text:
    breakup of self-gravitating rings, tori, and thick accretion disks. The Astrophysical Journal, 361(2):394

  • The interplay between chemistry and nucleation in the formation of carbonaceous dust in supernova ejecta

    Creator:
    Lazzati, Davide and Heger, Alexander
    Abstract:
    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....
    Resource Type:
    Article
    Full Text:
    a The Astrophysical Journal, 817:134 (11pp), 2016 February 1 doi:10.3847/0004-637X/817/2/134 © 2016

  • Gamma-ray burst spectra and spectral correlations from sub-photospheric Comptonization

    Creator:
    Chhotray, Atul and Lazzati, Davide
    Abstract:
    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...
    Resource Type:
    Article
    Full Text:
    correlations from sub-photospheric Comptonization. The Astrophysical Journal, 802(2), 132. doi:10.1088/0004