Astrophysics and Astronomy Commons^™

Investigations Of Metastable Ca2Iro4 Epitaxial Thin-Films: Systematic Comparison With Sr2Iro4 And Ba2Iro4, Maryam Souri, John H. Gruenewald, Jsaminka Terzic, Joseph W. Brill, Gang Cao, Sung S. Ambrose Seo

Physics and Astronomy Faculty Publications

We have synthesized thermodynamically metastable Ca₂IrO₄ thin-films on YAlO₃ (110) substrates by pulsed laser deposition. The epitaxial Ca₂IrO₄ thin-films are of K₂NiF₄-type tetragonal structure. Transport and optical spectroscopy measurements indicate that the electronic structure of the Ca₂IrO₄ thin-films is similar to that of J_eff = 1/2 spin-orbit-coupled Mott insulator Sr₂IrO₄ and Ba₂IrO₄, with the exception of an increased gap energy. The gap increase is to be expected in Ca₂IrO₄ due to its increased octahedral rotation …

Kelt-14b And Kelt-15b: An Independent Discovery Of Wasp-122b And A New Hot Jupiter, J. E. Rodriguez, K. D. Colón, K. G. Stassun, D. Wright, P. A. Cargile, D. Bayliss, J. Pepper, K. A. Collins, R. B. Kuhn, M. B. Lund, R. J. Siverd, G. Zhou, B. S. Gaudi, C. G. Tinney, K. Penev, T. G. Tan, C. Stockdale, I. A. Curtis, D. James, S. Udry, D. Segransan, A. Bieryla, D. W. Latham, T. G. Beatty, J. D. Eastman, G. Myers, J. Bartz, J. Bento, Eric L.N. Jensen, T. E. Oberst, D. J. Stevens

Physics & Astronomy Faculty Works

We report the discovery of KELT-14b and KELT-15b, two hot Jupiters from the KELT-South survey. KELT-14b, an independent discovery of the recently announced WASP-122b, is an inflated Jupiter mass planet that orbits a $\sim {5.0}_{-0.7}^{+0.3}$ Gyr, V = 11.0, G2 star that is near the main sequence turnoff. The host star, KELT-14 (TYC 7638-981-1), has an inferred mass ${M}_{*}$ = ${1.18}_{-0.07}^{+0.05}$ M⊙ and radius ${R}_{*}$ = $1.37\pm -0.08$ R⊙, and has ${T}_{{\rm{eff}}}$ = ${5802}_{-92}^{+95}$ K, $\mathrm{log}{g}_{*}$ = ${4.23}_{-0.04}^{+0.05}$ and $[{\rm{Fe}}/{\rm{H}}]$ = 0.33 ± −0.09. The planet orbits with a period of 1.7100588 ± 0.0000025 days (T0 = 2457091.02863 ± 0.00047) …

Stellar Mass–Gas-Phase Metallicity Relation At 0.5 ≤ Z ≤ 0.7: A Power Law With Increasing Scatter Toward The Low-Mass Regime, Yicheng Guo, David C. Koo, Yu Lu, John C. Forbes, Marc Rafelski, Jonathan R. Trump, Ricardo Amorín, Guillermo Barro, Romeel Davé, S. M. Faber, Nimish P. Hathi, Hassen Yesuf, Michael C. Cooper, Avishai Dekel, Puragra Guhathakurta, Evan N. Kirby, Anton M. Koekemoer, Pablo G. Pérez-González, Lihwai Lin, Jeffery A. Newman, Joel R. Primack, David J. Rosario, Christopher N. A. Willmer, Renbin Yan

Physics and Astronomy Faculty Publications

We present the stellar mass (M_*)–gas-phase metallicity relation (MZR) and its scatter at intermediate redshifts (0.5 ≤ z ≤ 0.7) for for 1381 field galaxies collected from deep spectroscopic surveys. The star formation rate (SFR) and color at a given M_* of this magnitude-limited (R ≲ 24 AB) sample are representative of normal star-forming galaxies. For masses below 10⁹ M_☉ our sample of 237 galaxies is ~10 times larger than those in previous studies beyond the local universe. This huge gain in sample size enables superior constraints on the MZR and its scatter …

Dynamic Flaring Non-Potential Fields On Quiet Sun Networks Scales, David L. Chesney, Hakeem M. Oluseyi, Norton B. Orange

Aerospace, Physics, and Space Science Faculty Publications

We report on the identification of dynamic flaring non-potential structures on quiet Sun (QS) supergranular network scales. Data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory allow for the high spatial and temporal resolution of this diverse class of compact structures. The rapidly evolving nonpotential events presented here, with lifetimes <10 minutes, are on the order of 10″ in length. Thus, they contrast significantly with well-known active region (AR) non-potential structures such as high-temperature X-ray and EUV sigmoids (>100″) and micro-sigmoids (>10″) with lifetimes on the order of hours to days. The photospheric magnetic field environment derived from the Helioseismic and Magnetic Imager shows a lack of evidence for these flaring non-potential fields being associated with significant concentrations of bipolar magnetic elements. Of much …

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

Publications

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 ion density in the …

Studying Solar Limb Darkening In H-Alpha With A Coronado Pst, Jessica N. Farrell, Jennifer Birriel

Celebration of Student Scholarship Poster Sessions Archive

No abstract provided.

Extending The Supermassive Black Hole Mass-Pitch Angle Relation To Moderate Redshifts, Logan H. Jones

Physics Undergraduate Honors Theses

I extend the empirical correlation between central supermassive black hole mass M and spiral arm pitch angle P in spiral galaxies to intermediate redshifts using a sample of 14 type 1 Seyfert galaxies. Nuclear black hole masses are measured from the widths and luminosities of the broad Hβ and MgII emission lines, and pitch angles are measured using two independent image analysis techniques. I find the best-fit relation log(M/M☉) = (8.31 ± 0.28) − (0.058 ± 0.016)P, which indicates little to no evolution compared to the published M-P relation for local spirals.

Star Formation In Ring Galaxies, Susan C. Olmsted

Undergraduate Honors Theses

Ring galaxies are specific types of interacting galaxies in which a smaller galaxy has passed through the center of the disk of another larger galaxy. The intrusion of the smaller galaxy causes the structure of the larger galaxy to compress as the smaller galaxy falls through, and to recoil back after the smaller galaxy passes through, hence the ring-like shape. In our research, we studied the star-forming regions of a sample of ring galaxies and compared to those of other interacting galaxies and normal galaxies. Using UV, optical, and IR archived images in twelve wavelengths from three telescopes, we analyzed …

The Sluggs Survey*: Exploring The Globular Cluster Systems Of The Leo Ii Group And Their Global Relationships, Sreeja Kartha, Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky, Jay Strader, Lee Spitler, Zachary Jennings, Joel Roediger

Faculty Publications

We present an investigation of the globular cluster (GC) systems of NGC 3607 and NGC 3608 as part of the ongoing SLUGGS (SAGES Legacy Unifying Globulars and GalaxieS) survey. We use wide-field imaging data from the Subaru telescope in the g, r and i filters to analyse the radial density, colour and azimuthal distributions of both GC systems. With the complementary kinematic data obtained from the Keck II telescope, we measure the radial velocities of a total of 81 GCs. Our results show that the GC systems of NGC 3607 and NGC 3608 have a detectable spatial extent of ∼15 …

Kenotic Effluent Panapotheism, Christopher E. Etter

Master of Arts in Religious Studies (M.A.R.S. Theses)

In these times of changing and evolving scientific discovery, philosophy and theology are at a critical juncture where they stand to lose all relevance if they are unable to keep up with the wealth of new knowledge and discoveries. Among the recent attempts in philosophy and theology to reconcile the relationship between science and these fields is Process Theology. Process Theology owes its origins to the 20th Century American philosopher Alfred North Whitehead. Whitehead and the philosophers and theologians he has influenced have developed a myriad of new theologies that all attempt to incorporate the new sciences, such as Quantum …

Defect Assisted Growth Of Copper-Silicide Nanostructures On Si(100) And Si(111), Endu Sekhar Srinadhu

All Dissertations

As the dimensions of the smallest feature on the integrated circuit has minia-turized into the range of tens of nanometers, patterning of highly ordered nanos-tructures with tunable size and shape in large scale on the surface of substrate is highly demanding and increasingly challenges the limits of nanolithography. To over-come the conventional lithographic limitations, self assembled methods have been explored. While strain driven self assembly is widely viewed as a promising technique for patterning at the nanoscale, to follow this approach and create structures in a desired manner, a reliable means to engineer and characterize the shape and sizes of …

Topics In The Detection Of Gravitational Waves From Compact Binary Inspirals, Shasvath Jagat Kapadia

Graduate Theses and Dissertations

Orbiting compact binaries - such as binary black holes, binary neutron stars and neutron star-black hole binaries - are among the most promising sources of gravitational waves observable by ground-based interferometric detectors. Despite numerous sophisticated engineering techniques, the gravitational wave signals will be buried deep within noise generated by various instrumental and environmental processes, and need to be extracted via a signal processing technique referred to as matched filtering.

Matched filtering requires large banks of signal templates that are faithful representations of the true gravitational waveforms produced by astrophysical binaries. The accurate and efficient production of templates is thus crucial …

Schwarzschild Spacetime And Friedmann-Lemaitre-Robertson-Walker Cosmology, Zachary Cohen

Honors Scholar Theses

The advent of General Relativity via Einstein's field equations revolutionized our understanding of gravity in our solar system and universe. The idea of General Relativity posits that gravity is entirely due to the geometry of the universe -- that is, the mass distribution throughout the universe results in the ``curving" of spacetime, which gives us the physics we see on a large scale. In the framework of General Relativity, we find that the universe behaves differently than was predicted in the model of gravitation developed by Newton. We will derive the general relativistic model for a simple system near a …

Investigating Mineral Stability Under Venus Conditions: A Focus On The Venus Radar Anomalies, Erika Kohler

Graduate Theses and Dissertations

Radar studies of the surface of Venus have identified regions with high radar reflectivity concentrated in the Venusian highlands: between 2.5 and 4.75 km above a planetary radius of 6051 km, though it varies with latitude. Previous research has proposed several theories on the source of these anomalies, including increased surface roughness, metallic materials with higher dielectric constants, or ferroelectric materials. Prior work suggests several processes that could be the origin of these anomalies, such as surface-atmospheric interactions or low lying clouds or fog. Alternatively, these anomalies could result from a semi-metallic compound trapped at the cooler conditions in the …

Teaching Numerical Methods In The Context Of Galaxy Mergers, Maria Kourjanskaia

Physics

Methods of teaching numerical methods to solve ordinary differential equations in the context of galaxy mergers were explored. The research published in a paper by Toomre and Toomre in 1972 describing the formation of galactic tails and bridges from close tidal interactions was adapted into a project targeting undergraduate physics students. Typically undergraduate physics students only take one Computational Physics class in which various techniques and algorithms are taught. Although it is important to study computational physics techniques, it is just as important to apply this knowledge to a problem that is representative of what computational physics researchers are investigating …

The Size And Shape Of The Milky Way Disc And Halo From M-Type Brown Dwarfs In The Borg Survey., Isabel Van Vledder, Dieuwertje Van Der Vlugt, Benne W. Holwerda, M. A. Kenworthy, R. J. Bouwens, M. Trenti

Faculty and Staff Scholarship

We have identified 274 M-type brown dwarfs in the Hubble Space Telescope's Wide Field Camera 3 pure parallel fields from the Brightest of Reionizing Galaxies (BoRG) survey for high-redshift galaxies. These are near-infrared observations with multiple lines of sight out of our Milky Way. Using these observed M-type brown dwarfs, we fitted a Galactic disc and halo model with a Markov chain Monte Carlo analysis. This model worked best with the scalelength of the disc fixed at h = 2.6 kpc. For the scaleheight of the disc, we found z0=0.29+0.02−0.019 z0=0.29−0.019+0.02 kpc and for the central number density, ρ0=0.29+0.20−0.13 ρ0=0.29−0.13+0.20 …

Optical Tracking And Spectral Characterization Of Cubesats For Operational Missions, Forrest Gasdia

Doctoral Dissertations and Master's Theses

Orbital debris in low Earth orbit is of growing concern to operational satellites from the government and commercial sector. With an uptick in worldwide satellite launches and the growing adoption of the CubeSat standard, the number of small objects in orbit are increasing at a faster pace than ever. As a result, a cascading collision event seems inevitable in the near future.

The United States Strategic Command tracks and determines the orbit of resident space objects using a worldwide network of radar and optical sensors. However, in order to better protect space assets, there has been increased interest in not …

The Sluggs Survey: Globular Clusters And The Dark Matter Content Of Early-Type Galaxies, Duncan Forbes, Adebusola Alabi, Aaron Romanowsky, Jean Brodie, Jay Strader, Christopher Usher, Vincenzo Pota

Faculty Publications

No abstract provided.

Geological Conditions Required For The Fluvial Erosion Of Titan’S Impact Craters, Rebeca M. Kinser

Theses and Dissertations

In comparison to other icy satellites, Titan has a small number of impact craters on its surface. Its dense atmosphere screens smaller impactors from the surface, but this alone does not account for the lack of impact craters, especially at large diameters. This suggests that Titan has a relatively young surface and/or erosional processes have effectively removed craters from its surface. For example, fluvial erosion could degrade craters such that they would be unrecognizable from an orbiting spacecraft such as Cassini. The amount of erosion, however, will depend on a number of factors including the geological and meteorological conditions of …

An Apparatus For Studying Electrical Breakdown In Liquid Helium At 0.4 K And Testing Electrode Materials For The Neutron Electric Dipole Moment Experiment At The Spallation Neutron Source, T. M. Ito, J. C. Ramsey, W. Yao, D. H. Beck, V. Cianciolo, S. M. Clayton, Christopher B. Crawford, S. A. Currie, B. W. Filippone, W. C. Griffith, M. Makela, R. Schmid, G. M. Seidel, Z. Tang, D. Wagner, W. Wei, S. E. Williamson

Physics and Astronomy Faculty Publications

We have constructed an apparatus to study DC electrical breakdown in liquid helium at temperatures as low as 0.4 K and at pressures between the saturated vapor pressure and ∼600 Torr. The apparatus can house a set of electrodes that are 12 cm in diameter with a gap of 1–2 cm between them, and a potential up to ±50 kV can be applied to each electrode. Initial results demonstrated that it is possible to apply fields exceeding 100 kV/cm in a 1 cm gap between two electropolished stainless steel electrodes 12 cm in diameter for a wide range of pressures …