Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, 2017 University of Arkansas, Fayetteville
Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, Amanda Schilling
Theses and Dissertations
I have investigated the energy output of active galactic nuclei (AGN) in order to understand how these objects evolve and the impact they may have on host galaxies. First, I looked at a sample of 96 AGN at redshifts $z \sim 2, 3,$ and $4$ which have imaging and thus luminosity measurements in the $griz$ and $JHK$ observed wavebands. For these galaxies, I have co-epochal data across those bands which accounted for variability in AGN luminosity. I used the luminosity measurements in the five bands to construct spectral energy distributions (SED) in the emitted optical-UV bands for each AGN. I ...
Physoon - Radiation Detection In Various High Altitude Environments, 2017 DePaul University
Physoon - Radiation Detection In Various High Altitude Environments, Christopher Helmerich
2017 Academic High Altitude Conference
Physoon is a high altitude ballooning payload designed and built by members of the Space Hardware Club for the purpose of comparing cosmic and terrestrial radiation from a variety of environmental conditions, including clear days, night times, solar events (eclipses, solar flares, coronal mass ejections), and thunderstorms. Over three design iterations, Physoon has flown eleven times with various combinations of Geiger counters sensors: a low energy Alpha-Beta-Gamma detector, an unshielded high-energy Beta-Gamma detector, and a shielded high-energy Beta-Gamma detector. One of these iterations successfully recovered data from high altitude during totality of the Great American Solar Eclipse. Another iteration was ...
Martian Cave Air-Movement Via Helmholtz Resonance, 2017 U.S. Geological Survey
Martian Cave Air-Movement Via Helmholtz Resonance, Kaj E. Williams, Timothy N. Titus, Chris H. Okubo, Glen E. Cushing
International Journal of Speleology
Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs) on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed.
Temperature Variations In The Dayside Magnetosheath And Their Dependence On Ion-Scale Magnetic Structures: Themis Statistics And Measurements By Mms, A. P. Dimmock, A. Osmane, T. I. Pulkkinen, K. Nykyri, E. Kilpua
The magnetosheath contains an array of waves, instabilities, and nonlinear magnetic structures which modify global plasma properties by means of various wave-particle interactions. The present work demonstrates that ion-scale magnetic field structures (∼0.2–0.5 Hz) observed in the dayside magnetosheath are statistically correlated to ion temperature changes on orders 10–20% of the background value. In addition, our statistical analysis implies that larger temperature changes are in equipartition to larger amplitude magnetic structures. This effect was more pronounced behind the quasi-parallel bow shock and during faster solar wind speeds. The study of two separate intervals suggests that this ...
Shape Modeling And Boulder Napping Of Asteroid 1992 Uy4., 2017 University of Louisville
Shape Modeling And Boulder Napping Of Asteroid 1992 Uy4., Nicholas D Duong
College of Arts & Sciences Senior Honors Theses
In August 2005, the near-Earth Asteroid 1992 UY4 made a close flyby, coming within 0.04 au of our planet. Between the dates of 1-10 August 2005, it was observed via delay-Doppler radar imaging by the Arecibo Observatory (2380 MHz, 13 cm) and the DSS-14 antenna at the Goldstone Deep Space Communications Complex (8560 MHz, 3.5 cm). The images achieve a resolution as fine as 7.5 m/pixel and reveal a lumpy and modestly asymmetric object. The images also revealed the presence of numerous large boulders/blocks on the surface of 1992 UY4. By using the modeling software ...
Imf Dependence Of Energetic Oxygen And Hydrogen Ion Distributions In The Near-Earth Magnetosphere, 2017 Chinese Academy of Sciences
Imf Dependence Of Energetic Oxygen And Hydrogen Ion Distributions In The Near-Earth Magnetosphere, H. Luo, E. A. Kronberg, K. Nykyri, K. J. Trattner, P. W. Daly, G. X. Chen, A. M. Du, Y. S. Ge
Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (> ~274 keV) from Cluster/Research with Adaptive Particle Imaging Detectors were used to statistically study the energetic ion distributions in the near-Earth region. The dawn-dusk asymmetries of the distributions in three different regions (dayside magnetosphere, near-Earth nightside plasma sheet, and tail plasma sheet) are examined in Northern and Southern Hemispheres. The results show that the energetic ion distributions ...
Using Student Characteristics, Student Spatial-Content Knowledge, And Teacher Spatial-Content Knowledge To Predict Student Spatial-Content Knowledge Of Lunar Phases, Kyle A. Curry
Theses and Dissertations--Science, Technology, Engineering, and Mathematics (STEM) Education
Student demographic characteristics of gender and race/ethnicity, students’ spatial-content knowledge as measured by pre-instructional performance on the Lunar Phases Concept Inventory (LPCI) (Lindell & Olsen), and post-instructional performance on the Purdue Visualization of Rotations Test (PSVT) (Bodner & Guay, 1997), and teachers’ spatial-content knowledge as measured by the two assessments were considered to predict students’ overall understanding of lunar phases as measured by post-instructional results on the LPCI. A mixed modeling approach was used in a hierarchal manner to evaluate the student learning outcomes. Results showed that student gender was not a significant predictor of post-instructional student performance, but students who ...
Intergalactic Hi And Ovi: A Survey Of 259 Low-Z Cos Absorbers With Reference To Ionization Mechanics, 2017 University of Colorado, Boulder
Intergalactic Hi And Ovi: A Survey Of 259 Low-Z Cos Absorbers With Reference To Ionization Mechanics, Shannon Osborne
Undergraduate Honors Theses
Modern astrophysics still lacks a strong understanding of the Intergalactic Medium (IGM), particularly the Warm-Hot Intergalactic Medium (WHIM; T = 105 – 107 K). To better understand the distribution and temperature of this gas, absorption-line observations along AGN sight lines from the Cosmic Origins Spectrograph onboard the Hubble Space Telescope (COS/HST) were analyzed (see Danforth et al. 2016). Here we present the largest analysis to date of IGM systems detected in both HI and OVI: 259 absorbers along 52 sight lines. We separate these systems into aligned and non-aligned categories based on the velocity separation of the HI and ...
Electrostatic Mechanics Of Dust Lofting And Transport On Airless Planetary Bodies, 2017 University of Colorado, Boulder
Electrostatic Mechanics Of Dust Lofting And Transport On Airless Planetary Bodies, Joseph Schwan
Undergraduate Honors Theses
As airless planetary bodies are directly exposed to solar ultraviolet radiation and plasma, an environment that fosters dust charging within planetary regolith will result, producing dust mobilization and transport. A multitude of unsolved in-situ planetary observations linked to electrostatic processes exist, ranging from dust ponds on the asteroid Eros, to intermittently appearing radial spokes in Saturn’s rings, and even to the lunar horizon glow. Available charging models could not adequately explain any of these phenomena. Through careful experimentation a new “Patched Charge Model” has been developed at the NASA/SSERVI’s Institute for Modeling Plasma, Atmospheres and Cosmic Dust ...
Astrophysical Accretion And Feedback: The Bayesian Linchpin Of Theory And Observation, 2017 University of Massachusetts - Amherst
Astrophysical Accretion And Feedback: The Bayesian Linchpin Of Theory And Observation, Shawn Roberts
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 ...
Emplacement Of The Foy, Hess And Pele Offset Dykes At The Sudbury Impact Structure, Canada, 2016 The University of Western Ontario
Emplacement Of The Foy, Hess And Pele Offset Dykes At The Sudbury Impact Structure, Canada, Eric A. Pilles
Electronic Thesis and Dissertation Repository
The 1.85 Ga Sudbury impact structure is the remnant of what is generally considered to have been an ~150–200 km diameter impact basin in central Ontario, Canada. The so-called Offset Dykes are impact melt dykes that are found concentrically around – and extending radially outward from – the Sudbury Igneous Complex (SIC), a ~3 km thick differentiated impact melt sheet. The dykes are typically composed of two main phases of granodiorite: an inclusion- and sulfide-rich granodiorite in the centre of the dyke, and an inclusion- and sulfide-poor granodiorite along the margins of the dyke. This study uses a combination of ...
Rethinking The Polar Cap: Eccentric Dipole Structuring Of Ulf Power At The Highest Corrected Geomagnetic Latitudes, Kevin D. Urban, Andrew J. Gerrard, Louis J. Lanzerotti, Allan T. Weatherwax
Physics Faculty Publications
The day-to-day evolution and statistical features of Pc3-Pc7 band ultralow frequency (ULF) power throughout the southern polar cap suggest that the corrected geomagnetic (CGM) coordinates do not adequately organize the observed hydromagnetic spatial structure. It is shown that that the local-time distribution of ULF power at sites along CGM latitudinal parallels exhibit fundamental differences and that the CGM latitude of a site in general is not indicative of the site's projection into the magnetosphere. Thus, ULF characteristics observed at a single site in the polar cap cannot be freely generalized to other sites of similar CGM latitude but separated ...
Dicke’S Superradiance In Astrophysics, 2016 The University of Western Ontario
Dicke’S Superradiance In Astrophysics, Fereshteh Rajabi
Electronic Thesis and Dissertation Repository
It is generally assumed that in the interstellar medium much of the emission emanating from atomic and molecular transitions within a radiating gas happen independently for each atom or molecule, but as was pointed out by R. H. Dicke in a seminal paper several decades ago this assumption does not apply in all conditions. As will be discussed in this thesis, and following Dicke’s original analysis, closely packed atoms/molecules can interact with their common electromagnetic field and radiate coherently through an effect he named superradiance. Superradiance is a cooperative quantum mechanical phenomenon characterized by high intensity, spatially compact ...
General Relativity And Differential Geometry, 2016 Union College - Schenectady, NY
General Relativity And Differential Geometry, Harry Hausner
Honors Theses and Student Projects
The Dawn–Dusk Asymmetry Of Ion Density In The Dayside Magnetosheath And Its Annual Variability Measured By Themis, Andrew P. Dimmock, Tuija I. Pulkkinen, Adnane Osmane, Katariina Nykyri
The local and global plasma properties in the magnetosheath play a fundamental role in regulating solar wind–magnetosphere coupling processes. However, the magnetosheath is a complex region to characterise as it has been shown theoretically, observationally and through simulations that plasma properties are inhomogeneous, non-isotropic and asymmetric about the Sun-Earth line. To complicate matters, dawn–dusk asymmetries are sensitive to various changes in the upstream conditions on an array of timescales. The present paper focuses exclusively on dawn–dusk asymmetries, in particularly that of ion density. We present a statistical study using THEMIS data of the dawn–dusk asymmetry of ...
The Inner Gaseous Disks Of Herbig Be Stars, 2016 The University of Western Ontario
The Inner Gaseous Disks Of Herbig Be Stars, Parshati Patel
Electronic Thesis and Dissertation Repository
Herbig Ae/Be stars are intermediate mass (~2 to 20Msun) pre-main sequence stars that inherit a circumstellar disk of dust and gas from their formation phase. The region of this disk closest to the star is entirely gaseous because dust evaporates at the high temperatures there, and this gaseous region is currently poorly understood. Using non-LTE circumstellar disk codes to model the optical and near-infrared spectra of five, early-type (B0Ve to B2Ve) Herbig Be stars obtained with the Canada-France-Hawaii telescope ESPaDOnS instrument, the density structure of each inner gaseous disks was determined and estimates of the disk masses and ...
The Parallelization And Optimization Of The N-Body Problem Using Openmp And Openmpi, 2016 Gettysburg College
The Parallelization And Optimization Of The N-Body Problem Using Openmp And Openmpi, Nicholas J. Carugati
The focus of this research is exploring the efficient ways we can implement the NBody problem. The N-Body problem, in the field of physics, is a problem in which predicts or simulates the movements of planets and how they interact with each other gravitationally. For this research, we are viewing if the simulation can execute efficiently by delegating the heavy computational work through different cores of a CPU. The approach that is being used to figure this out is by integrating the parallelization API OpenMP and the message-passing library OpenMPI into the code. Rather than all the code executing on ...
Probing The Fitting Accuracy Of Active Galaxy Spectra, 2016 California Polytechnic State University, San Luis Obispo
Probing The Fitting Accuracy Of Active Galaxy Spectra, Aaron T. Line
Prior to this study, Dr. Vardha N. Bennert and collaborators selected a sample of ~100 local active galaxies to study the relationships between black hole mass and host galaxy properties. The broad Hβ width is necessary to determine black hole mass. This value is determined using a spectral decomposition code was scripted in IDL by Dr. Daeseong Park. The script fit spectral features and collected data for properties such as width of emission lines and continuum contribution percentages. The results were logged for further analysis.
To probe the accuracy of the fitting process, artificial spectra were created and fitted to ...
Rethinking Black Hole Accretion Discs, 2016 University of Colorado at Boulder
Rethinking Black Hole Accretion Discs, Greg Salvesen
Astrophysical & Planetary Sciences Graduate Theses & Dissertations
Accretion discs are staples of astrophysics. Tapping into the gravitational potential energy of the accreting material, these discs are highly efficient machines that produce copious radiation and extreme outflows. While interesting in their own right, accretion discs also act as tools to study black holes and directly influence the properties of the Universe. Black hole X-ray binaries are fantastic natural laboratories for studying accretion disc physics and black hole phenomena. Among many of the curious behaviors exhibited by these systems are black hole state transitions -- complicated cycles of dramatic brightening and dimming. Using X-ray observations with high temporal cadence, we ...
Fast-Moving Diffuse Auroral Patches: A New Aspect Of Daytime Pc3 Auroral Pulsations, 2016 Merrimack College
Fast-Moving Diffuse Auroral Patches: A New Aspect Of Daytime Pc3 Auroral Pulsations, Tetsuo Motoba, Yusuke Ebihara, Akira Kadokura, Mark J. Engebretson, Marc R. Lessard, Allan T. Weatherwax, Andrew J. Gerrard
Physics Faculty Publications
Auroral pulsations are a convenient diagnostic of wave-particle interactions in the magnetosphere. A case study of a daytime Pc3 (22–100 mHz) auroral pulsation event, measured with a ~2 Hz sampling all-sky camera at South Pole Station (74.4°S magnetic latitude) on 17 May 2012, is presented. The daytime Pc3 auroral pulsations were most active in a closed field line region where the aurora was dominated by diffuse green-line emissions and within ±2 h of magnetic local noon. Usually, but not always, the corresponding periodic variations were recorded with a colocated search coil magnetometer. Of particular interest is the ...