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Articles 2311 - 2340 of 8856

Full-Text Articles in Astrophysics and Astronomy

Quantum-Enhanced Advanced Ligo Detectors In The Era Of Gravitational-Wave Astronomy, M. Tse, Haocun Yu, N. Kijbunchoo, A. Fernandez-Galiana, P. Dupej, L. Barsotti, C. D. Blair, D. D. Brown, S. E. Dwyer, Karla E. Ramirez Dec 2019

Quantum-Enhanced Advanced Ligo Detectors In The Era Of Gravitational-Wave Astronomy, M. Tse, Haocun Yu, N. Kijbunchoo, A. Fernandez-Galiana, P. Dupej, L. Barsotti, C. D. Blair, D. D. Brown, S. E. Dwyer, Karla E. Ramirez

Physics & Astronomy Faculty Publications

The Laser Interferometer Gravitational Wave Observatory (LIGO) has been directly detecting gravitational waves from compact binary mergers since 2015. We report on the first use of squeezed vacuum states in the direct measurement of gravitational waves with the Advanced LIGO H1 and L1 detectors. This achievement is the culmination of decades of research to implement squeezed states in gravitational-wave detectors. During the ongoing O3 observation run, squeezed states are improving the sensitivity of the LIGO interferometers to signals above 50 Hz by up to 3 dB, thereby increasing the expected detection rate by 40% (H1) and 50% (L1).

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Plenty Of Stars On Display On Parkland's Campus, Erik Johnson Dec 2019

Plenty Of Stars On Display On Parkland's Campus, Erik Johnson

Natural Science Faculty

Since 1987, the William M. Staerkel Planetarium has brought the universe to Champaign-Urbana even if the skies are cloudy. Parkland College’s first president, William Staerkel (“star-kul”), dreamed of establishing a cultural center in campus, engaging the community in arts and sciences with a theater and a planetarium. That vision was realized at the end of his tenure and the planetarium was named in his honor.

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Assessing & Protecting Dark Night Skies In El Morro National Monument, Leslie Kobinsky Dec 2019

Assessing & Protecting Dark Night Skies In El Morro National Monument, Leslie Kobinsky

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Light pollution is causing the disappearance of dark night skies around the world. In the United States alone, 1/3 of people are unable to see the Milky Way where they live (Ramlagan, 2016). National Park Service sites contain some of the darkest skies in the country. Here at El Morro National Monument, these dark skies are a beautiful and healthy benefit to people in the local community and visitors traveling from afar. El Morro’s current park legislation does not include specific measures of protection for the night sky. This capstone project will create a baseline data set of night sky …

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Detection Of A Low-Mass Stellar Companion To The Accelerating A2iv Star Hr 1645, Robert J. De Rosa, Eric L. Nielsen, Julien Rameau, Gaspard Duchêne, Alexandra Z. Greenbaum, Jason J. Wang, S. Mark Ammons, Vanessa P. Bailey, Travis Barman, Joanna Bulger, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Thomas M. Esposito, Michael P. Fitzgerald, Katherine B. Follette, Benjamin L. Gerard, Stephen J. Goodsell, James R. Graham, Pascale Hibon, Justin Hom, Li Wei Hung, Patrick Ingraham, Paul Kalas, Quinn Konopacky, James E. Larkin, Bruce Macintosh, Jérôme Maire, Franck Marchis, Mark S. Marley, Christian Marois, Stanimir Metchev, Kimberly Ward-Duong, Et Al Dec 2019

Detection Of A Low-Mass Stellar Companion To The Accelerating A2iv Star Hr 1645, Robert J. De Rosa, Eric L. Nielsen, Julien Rameau, Gaspard Duchêne, Alexandra Z. Greenbaum, Jason J. Wang, S. Mark Ammons, Vanessa P. Bailey, Travis Barman, Joanna Bulger, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Thomas M. Esposito, Michael P. Fitzgerald, Katherine B. Follette, Benjamin L. Gerard, Stephen J. Goodsell, James R. Graham, Pascale Hibon, Justin Hom, Li Wei Hung, Patrick Ingraham, Paul Kalas, Quinn Konopacky, James E. Larkin, Bruce Macintosh, Jérôme Maire, Franck Marchis, Mark S. Marley, Christian Marois, Stanimir Metchev, Kimberly Ward-Duong, Et Al

Astronomy: Faculty Publications

The ∼500 Myr A2IV star HR 1645 has one of the most significant low-amplitude accelerations of nearby early-type stars measured from a comparison of the Hipparcos and Gaia astrometric catalogs. This signal is consistent with either a stellar companion with a moderate mass ratio (q ∼ 0.5) on a short period (P < 1 yr), or a substellar companion at a separation wide enough to be resolved with ground-based high-contrast imaging instruments; long-period equal-mass ratio stellar companions that are also consistent with the measured acceleration are excluded with previous imaging observations. The small but significant amplitude of the acceleration made HR 1645 a promising candidate for targeted searches for brown dwarf and planetary-mass companions around nearby, young stars. In this paper we explore the origin of the astrometric acceleration by modeling the signal induced by a wide-orbit M8 companion discovered with the Gemini Planet Imager, as well as the effects of an inner short-period spectroscopic companion discovered a century ago but not since followed up. We present the first constraints on the orbit of the inner companion, and demonstrate that it is a plausible cause of the astrometric acceleration. This result demonstrates the importance of vetting of targets with measured astrometric acceleration for short-period stellar companions prior to conducting targeted direct imaging surveys for wide-orbit substellar companions.

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New Foundation In The Sciences: Physics Without Sweeping Infinities Under The Rug, Florentin Smarandache, Victor Christianto, Robert Neil Boyd Dec 2019

New Foundation In The Sciences: Physics Without Sweeping Infinities Under The Rug, Florentin Smarandache, Victor Christianto, Robert Neil Boyd

Branch Mathematics and Statistics Faculty and Staff Publications

It is widely known among the Frontiers of physics, that “sweeping under the rug” practice has been quite the norm rather than exception. In other words, the leading paradigms have strong tendency to be hailed as the only game in town. For example, renormalization group theory was hailed as cure in order to solve infinity problem in QED theory. For instance, a quote from Richard Feynman goes as follows: “What the three Nobel Prize winners did, in the words of Feynman, was "to get rid of the infinities in the calculations. The infinities are still there, but now they can …

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Astrodynamics Of The Next Generation Space Weather Prediction Mission, Mark Herring Dec 2019

Astrodynamics Of The Next Generation Space Weather Prediction Mission, Mark Herring

Doctoral Dissertations and Master's Theses

Accurate prediction of the solar wind properties, interplanetary magnetic field direction and various space weather phenomena becomes ever more important as our dependence on Earth orbiting spacecraft increases. Different solar wind drivers can lead both to enhancements and losses of relativistic electrons in the outer radiation belts, thus posing a major risk to satellites. To further our understanding of the Sun’s impact on the near Earth space environment, as well as to provide predictive capabilities, a mission placing monitoring satellites in key orbits in the inner Solar System is being proposed. As part of that effort, the possibility of using …

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A Compositional Analysis Of Artificial And Terrestrial Analog Martian Regolith Simulants, Beverly Watson Kemmerer Dec 2019

A Compositional Analysis Of Artificial And Terrestrial Analog Martian Regolith Simulants, Beverly Watson Kemmerer

Theses and Dissertations

Over the past 50 years, significant advances in the knowledge of the topography, climate, and geology of Mars have taken place. The global Martian regolith composition is highly basaltic, primarily composed of pyroxene, plagioclase, and olivine, a mixture of Fe oxides and Fe-Ti oxides, and some alteration minerals, i.e. sulfates, carbonates, and clays. The particle size distribution of Martian regolith ranges from 1 µm to 1000 µm, with average Martian soil grain sizes being 250 µm to 300 µm. These regolith properties, as well as geotechnical properties, all play a part in the outcome of certain in situ resource utilization …

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Event Reconstruction In The Advanced Particle-Astrophysics Telescope, Emily Ramey Dec 2019

Event Reconstruction In The Advanced Particle-Astrophysics Telescope, Emily Ramey

McKelvey School of Engineering Graduate Student Theses & Dissertations

The Advanced Particle-Astrophysics Telescope (APT) is a concept for a gamma-ray space telescope operating in the keV to MeV energy range. Due to the nature of the telescope and the physics of detection, reconstructing initial photon trajectories can be very computationally complex. This is a barrier to the real-time detection of astrophysical transient phenomena such as Gamma Ray Bursts (GRBs), and a faster reconstruction algorithm is needed in order to effectively study them. In this project, we develop such an algorithm based on Boggs & Jean (2000) and discuss the effects of certain algorithmic parameters on computational performance. For testing, …

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An Investigation Of Metal Sulfides As The Source Of The Low Emissivity Anomaly On The Highlands Of Venus, Sara Taeko Port Dec 2019

An Investigation Of Metal Sulfides As The Source Of The Low Emissivity Anomaly On The Highlands Of Venus, Sara Taeko Port

Graduate Theses and Dissertations

Since its detection in the 1960s the source of the unusual radar emissivity signal seen on several highlands on Venus has long eluded researchers. Researchers have determined that a mineral with a high dielectric constant could explain the signal. Using a Venus simulation chamber, we experimentally investigated this enigma to build upon the candidate mineral list that has been compiled over the last several decades. We tested the stability of 8 different minerals and elements at two to three different temperature/pressure regimes in three different gas mixtures meant to simulate the conditions found on Venus for a period of no …

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Raman Investigations On Gamma Irradiated Ipp-Vgcnf Nanocomposites: The Polymer's Tale, Dorina M. Chipara, Corina Secu, Karen Lozano, Mihail Secu, Mircea Chipara Dec 2019

Raman Investigations On Gamma Irradiated Ipp-Vgcnf Nanocomposites: The Polymer's Tale, Dorina M. Chipara, Corina Secu, Karen Lozano, Mihail Secu, Mircea Chipara

Physics & Astronomy Faculty Publications

Raman investigations on nanocomposites obtained by loading various amounts of vapor grown carbon nanofibers within an isotactic polypropylene matrix, and gamma irradiated in air, at various integral doses ranging between 0 and 27 kGy, are reported. The analysis is focused on the polymer's answers as revealed by Raman spectroscopy and investigate in detail the effect of ionizing radiation on the position of the Raman line originating from the polymer. The as-obtained data are correlated to the elastic features of the nanocomposites. A competition between gamma irradiation and loading by carbon nanofiber, resulting in the stretching of the polymeric matrix …

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A Unified Binary Neutron Star Merger Magnetar Model For The Chandra X-Ray Transients Cdf-S Xt1 And Xt2, Hui Sun, Ye Li, Bin-Bin Zhang, Bing Zhang, Franz E. Bauer, Yongquan Xue, Weimin Yuan Nov 2019

A Unified Binary Neutron Star Merger Magnetar Model For The Chandra X-Ray Transients Cdf-S Xt1 And Xt2, Hui Sun, Ye Li, Bin-Bin Zhang, Bing Zhang, Franz E. Bauer, Yongquan Xue, Weimin Yuan

Physics & Astronomy Faculty Research

Two bright X-ray transients were reported from the Chandra Deep Field South (CDF-S) archival data, namely CDF-S XT1 and XT2. Whereas the nature of the former is not identified, the latter was suggested as an excellent candidate for a rapidly spinning magnetar born from a binary neutron star (BNS) merger. Here we propose a unified model to interpret both transients within the framework of the BNS merger magnetar model. According to our picture, CDF-S XT2 is observed from the "free zone" where the magnetar spindown powered X-ray emission escapes freely, whereas CDF-S XT1 originates from the "trapped zone" where the …

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Tidal Destruction In A Low-Mass Galaxy Environment: The Discovery Of Tidal Tails Around Ddo 44, Jeffrey Carlin, Christopher Garling, Annika Peter, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Burçin Mutlu-Pakdil, Ragadeepika Pucha, Aaron Romanowsky, David Sand, Kristine Spekkens, Jay Strader, Beth Willman Nov 2019

Tidal Destruction In A Low-Mass Galaxy Environment: The Discovery Of Tidal Tails Around Ddo 44, Jeffrey Carlin, Christopher Garling, Annika Peter, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Burçin Mutlu-Pakdil, Ragadeepika Pucha, Aaron Romanowsky, David Sand, Kristine Spekkens, Jay Strader, Beth Willman

Faculty Publications

We report the discovery of a 1° (~50 kpc) long stellar tidal stream emanating from the dwarf galaxy DDO 44, a likely satellite of Local Volume galaxy NGC 2403 located ~70 kpc in projection from its companion. NGC 2403 is a roughly Large Magellanic Cloud (LMC) stellar-mass galaxy 3 Mpc away, residing at the outer limits of the M81 group. We are mapping a large region around NGC 2403 as part of our Magellanic Analogs' Dwarf Companions and Stellar Halos survey, reaching point-source depths (90% completeness) of (g, i) = (26.5, 26.2). Density maps of old, metal-poor RGB stars reveal …

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A Hubble Pancet Study Of Hat-P-11b: A Cloudy Neptune With A Low Atmospheric Metallicity, Yayaati Chachan, Heather A. Knutson, Peter Gao, Tiffany Kataria, Ian Wong, Gregory W. Henry, Bjorn Benneke, Michael Zhang, Joanna Barstow, Jacob L. Bean, Thomas Mikal-Evans, Nikole K. Lewis, Megan Mansfield, Mercedes López-Morales, Nikolay Nikolov, David K. Sing, Hannah Wakeford Nov 2019

A Hubble Pancet Study Of Hat-P-11b: A Cloudy Neptune With A Low Atmospheric Metallicity, Yayaati Chachan, Heather A. Knutson, Peter Gao, Tiffany Kataria, Ian Wong, Gregory W. Henry, Bjorn Benneke, Michael Zhang, Joanna Barstow, Jacob L. Bean, Thomas Mikal-Evans, Nikole K. Lewis, Megan Mansfield, Mercedes López-Morales, Nikolay Nikolov, David K. Sing, Hannah Wakeford

Information Systems and Engineering Management Research Publications

We present the first comprehensive look at the 0.35–5 μm transmission spectrum of the warm (∼800 K) Neptune HAT-P-11b derived from 13 individual transits observed using the Hubble and Spitzer Space Telescopes. Along with the previously published molecular absorption feature in the 1.1–1.7 μm bandpass, we detect a distinct absorption feature at 1.15 μm and a weak feature at 0.95 μm, indicating the presence of water and/or methane with a combined significance of 4.4σ. We find that this planet's nearly flat optical transmission spectrum and attenuated near-infrared molecular absorption features are best matched by models incorporating a high-altitude cloud layer. …

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Search For Gravitational-Wave Signals Associated With Gamma-Ray Bursts During The Second Observing Run Of Advanced Ligo And Advanced Virgo, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration Nov 2019

Search For Gravitational-Wave Signals Associated With Gamma-Ray Bursts During The Second Observing Run Of Advanced Ligo And Advanced Virgo, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of <9.38 × 10−6 (modeled) and 3.1 × 10−4 (unmodeled). We do not find any significant evidence for …

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Meps Data Assimilation System, Robert W. Schunk, Larry Gardner Nov 2019

Meps Data Assimilation System, Robert W. Schunk, Larry Gardner

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For the current funding opportunity we propose to develop a master system that will enhance the user interface to the MEPS model and enable the scientific community to efficiently use the model. Furthermore, we will build and automate validation tools and improve the efficiency and robustness of the MEPS ensemble averaging scheme. Finally, we will explore the nest step toward a major advancement in MEPS b significantly improving the spatial resolution of one of the data assimilation models to explore meso- and small-scale features.

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Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration Nov 2019

Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

The detection of gravitational waves by Advanced LIGO and Advanced Virgo provides an opportunity to test general relativity in a regime that is inaccessible to traditional astronomical observations and laboratory tests. We present four tests of the consistency of the data with binary black hole gravitational waveforms predicted by general relativity. One test subtracts the best-fit waveform from the data and checks the consistency of the residual with detector noise. The second test checks the consistency of the low- and high-frequency parts of the observed signals. The third test checks that phenomenological deviations introduced in the waveform model (including in …

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Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, B. P. Abbott, S. Mukherjee Nov 2019

Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, B. P. Abbott, S. Mukherjee

Physics & Astronomy Faculty Publications

The detection of gravitational waves by Advanced LIGO and Advanced Virgo provides an opportunity to test general relativity in a regime that is inaccessible to traditional astronomical observations and laboratory tests. We present four tests of the consistency of the data with binary black hole gravitational waveforms predicted by general relativity. One test subtracts the best-fit waveform from the data and checks the consistency of the residual with detector noise. The second test checks the consistency of the low- and high-frequency parts of the observed signals. The third test checks that phenomenological deviations introduced in the waveform model (including in …

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Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu Nov 2019

Morphological Signatures Induced By Dust Back Reactions In Discs With An Embedded Planet, Chao-Chin Yang, Zhaohuan Zhu

Physics & Astronomy Faculty Research

Recent observations have revealed a gallery of substructures in the dust component of nearby protoplanetary discs, including rings, gaps, spiral arms, and lopsided concentrations. One interpretation of these substructures is the existence of embedded planets. Not until recently, however, most of the modelling effort to interpret these observations ignored the dust back reaction to the gas. In this work, we conduct local-shearing-sheet simulations for an isothermal, inviscid, non-self-gravitating, razor-thin dusty disc with a planet on a fixed circular orbit. We systematically examine the parameter space spanned by planet mass (0.1Mth ≤ Mp ≤ 1Mth, where Mth is the thermal mass), …

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Wasp-52b. The Effect Of Star-Spot Correction On Atmospheric Retrievals, Giovanni Bruno, Nikole K. Lewis, Munazza K. Alam, Mercedes López-Morales, Joanna K. Barstow, Hannah R. Wakeford, David K. Sing, Gregory W. Henry, Gilda E. Ballester, Vincent Bourrier, Lars A. Buchhave, Ofer Cohen, Thomas Mikal-Evans, Antonio García Muñoz, Panayotis Lavvas, Jorge Sanz-Forcada Nov 2019

Wasp-52b. The Effect Of Star-Spot Correction On Atmospheric Retrievals, Giovanni Bruno, Nikole K. Lewis, Munazza K. Alam, Mercedes López-Morales, Joanna K. Barstow, Hannah R. Wakeford, David K. Sing, Gregory W. Henry, Gilda E. Ballester, Vincent Bourrier, Lars A. Buchhave, Ofer Cohen, Thomas Mikal-Evans, Antonio García Muñoz, Panayotis Lavvas, Jorge Sanz-Forcada

Information Systems and Engineering Management Research Publications

We perform atmospheric retrievals on the full optical to infrared (0.3−5μm⁠) transmission spectrum of the inflated hot Jupiter WASP-52b by combining HST/STIS, WFC3 IR, and Spitzer/IRAC observations. As WASP-52 is an active star that shows both out-of-transit photometric variability and star-spot crossings during transits, we account for the contribution of non-occulted active regions in the retrieval. We recover a 0.1–10× solar atmospheric composition, in agreement with core accretion predictions for giant planets, and no significant contribution of aerosols. We also obtain a star-spots, a measure which is likely affected by the models used to fit instrumental effects in …

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Graded Quivers, Generalized Dimer Models And Toric Geometry, Sebastián Franco, Azeem Hasan Nov 2019

Graded Quivers, Generalized Dimer Models And Toric Geometry, Sebastián Franco, Azeem Hasan

Publications and Research

The open string sector of the topological B-model on CY (m+2)-folds is described by m-graded quivers with superpotentials. This correspondence extends to general m the well known connection between CY (m+2)-folds and gauge theories on the world-volume of D(5-2m)-branes for m = 0, ..., 3. We introduce m-dimers, which fully encode the m-graded quivers and their superpotentials, in the case in which the CY (m+2)-folds are toric. Generalizing the well known m = 1,2 cases, m-dimers significantly simplify the connection between geometry and m-graded quivers. A key …

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Measurements Of The 16c + 12c And 16c + 13c Fusion Cross Sections With Implications For Astrophysics, Ashley Ann Hood Nov 2019

Measurements Of The 16c + 12c And 16c + 13c Fusion Cross Sections With Implications For Astrophysics, Ashley Ann Hood

LSU Doctoral Dissertations

The fusion of neutron-rich nuclei is of interest to nuclear astrophysics and nuclear structure. X-ray superbursts are powered by runaway thermonuclear burning deep inside of a neutron star, where heating from the pycnonuclear fusion of neutron-rich isotopes is an important heat source. Experimental measurements of fusion cross sections of neutron-rich isotopes have provided insights regarding nucleon transfer and nuclear structure properties affecting fusion. Recently, the 15C + 12C total fusion cross section was measured using a 15C beam produced by the in-flight beam production facility, which is part of the Argonne Tandem LINAC Accelerator System (ATLAS) at …

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The Halo Mass Function Of Late-Type Galaxies From H I Kinematics, Pengfei Li, Stacy S. Mcgaugh Nov 2019

The Halo Mass Function Of Late-Type Galaxies From H I Kinematics, Pengfei Li, Stacy S. Mcgaugh

Faculty Scholarship

We present an empirical method to measure the halo mass function (HMF) of galaxies. We determine the relation between the H i line width from single-dish observations and the dark matter halo mass (M 200) inferred from rotation-curve fits in the Spitzer Photometry and Accurate Rotation Curves (SPARC) database, then we apply this relation to galaxies from the H i Parkes All Sky Survey (HIPASS) to derive the HMF. This empirical HMF is well fit by a Schechter function, and matches that expected in the Λ Cold Dark Matter (ΛCDM) model over the range 1010.5 < M 200 < 1012 M o˙. More massive halos must be poor in neutral gas to maintain consistency with the power law predicted by ΛCDM. We detect no discrepancy at low masses. The lowest halo mass probed by HIPASS, however, is just greater than the mass scale where the Local Group missing satellite problem sets in. The integrated mass density associated with the dark matter halos of H i-detected galaxies sums to Ωm,gal ≈ 0.03 over the probed mass range.

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Using Natural Phenomena To Study The Ionosphere, Joseph Benjamin Malins Nov 2019

Using Natural Phenomena To Study The Ionosphere, Joseph Benjamin Malins

Physics & Astronomy ETDs

This dissertation explores novel techniques for observing the ionosphere using natural signals. The ionosphere is a region of plasma hundreds of kilometers above the Earth that affects communication and remote sensing applications across the world. Traditional techniques for observing the ionosphere involve using man made radio signals, either to reflect the signal at HF frequencies or to pass several signals through the ionosphere and compare the difference the ionosphere makes in the signals. However, such techniques are limited by the ability of equipment to produce these signals and by the numerous laws and regulations governing transmission of signals in the …

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Realistic Sensitivity Curves For Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Joseph D. Romano, Tristan L. Smith Nov 2019

Realistic Sensitivity Curves For Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Joseph D. Romano, Tristan L. Smith

Physics & Astronomy Faculty Publications

We construct realistic sensitivity curves for pulsar timing array searches for gravitational waves, incorporating both red and white noise contributions to individual pulsar noise spectra, and the effect of fitting to a pulsar timing model. We demonstrate the method on both simulated pulsars and a realistic array consisting of a subset of NANOGrav pulsars used in recent analyses. A comparison between the results presented here and measured upper limit curves from actual analyses shows agreement to tens of percent. The resulting sensitivity curves can be used to assess the detectability of predicted gravitational-wave signals in the nanohertz frequency band in …

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Evolution Of A Relativistic Electron Beam For Tracing Magnetospheric Field Lines, Andrew T. Powis, Peter Porazik, Michael Greklek-Mckeon, Kailas Amin, David Shaw, Igor D. Kaganovich, Jay R. Johnson, Ennio Sanchez Nov 2019

Evolution Of A Relativistic Electron Beam For Tracing Magnetospheric Field Lines, Andrew T. Powis, Peter Porazik, Michael Greklek-Mckeon, Kailas Amin, David Shaw, Igor D. Kaganovich, Jay R. Johnson, Ennio Sanchez

Faculty Publications

Tracing magnetic field-lines of the Earth's magnetosphere using beams of relativistic electrons will open up new insights into space weather and magnetospheric physics. Analytic models and a single-particle-motion code were used to explore the dynamics of an electron beam emitted from an orbiting satellite and propagating until impact with the Earth. The impact location of the beam on the upper atmosphere is strongly influenced by magnetospheric conditions, shifting up to several degrees in latitude between different phases of a simulated storm. The beam density cross-section evolves due to cyclotron motion of the beam centroid and oscillations of the beam envelope. …

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Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena Nov 2019

Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena

Physics & Astronomy ETDs

Scattering from randomly rough surfaces is a well-established sub area of electrodynamics. There remains much to be done since each surface and optical processes that may occur in within the scattering medium, and countless other scenarios, is different. There are also illumination models that describe lighting in a scene on the macroscopic scale where geometrical optics can be considered adequate. Of particular interest for us is the intersection of the physical scattering theories and the illumination models. We present two contributions: 1) A minimum of two independent images are needed since any opaque surface can be uniquely specified in terms …

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Secondary Infall In The Seyfert's Sextet: A Plausible Way Out Of The Short Crossing Time Paradox, Omar López-Cruz, Héctor Javier Ibarra-Medel, Sebastián F. Sánchez, Mark Birkinshaw, Christopher Añorve, Jorge K. Barrera-Ballesteros, Jesús Falcon-Barroso, Wayne A. Barkhouse, Juan P. Torres-Papaqui Nov 2019

Secondary Infall In The Seyfert's Sextet: A Plausible Way Out Of The Short Crossing Time Paradox, Omar López-Cruz, Héctor Javier Ibarra-Medel, Sebastián F. Sánchez, Mark Birkinshaw, Christopher Añorve, Jorge K. Barrera-Ballesteros, Jesús Falcon-Barroso, Wayne A. Barkhouse, Juan P. Torres-Papaqui

Physics Faculty Publications

We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly available data to investigate the star formation histories of galaxies in the Seyfert's Sextet (SS; HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories, we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turnaround, initially gas-rich galaxies crossed for the first time, consuming …

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High Power And Optomechanics In Advanced Ligo Detectors, Terra Christine Hardwick Nov 2019

High Power And Optomechanics In Advanced Ligo Detectors, Terra Christine Hardwick

LSU Doctoral Dissertations

In September 2015, a new era of astronomy began with the first direct detection of grav- itational waves from a binary black hole coalescence. The event was captured by the Laser Interferometer Gravitational-wave Observatory, comprised of two long-baseline interferometers, one in Livingston, LA and one in Hanford, WA. At the time of the first detection, the interferometers were part way through an upgrade to an advanced configuration and were operating with a strain sensitivity of just better than 10−23/Hz1/2 around 100Hz. The full Advanced LIGO design calls for sensitivity of a few parts in 10−24/Hz …

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Alpha Capture Reaction Rates For Nucleosynthesis Within An Ab Initio Framework, Alison Constance Dreyfuss Nov 2019

Alpha Capture Reaction Rates For Nucleosynthesis Within An Ab Initio Framework, Alison Constance Dreyfuss

LSU Doctoral Dissertations

Clustering in nuclear systems has broad impacts on all phases of stellar burning, and plays a significant role in our understanding of nucleosynthesis, or how and where nuclei are produced in the universe. The role of alpha particles in particular is extremely important for nuclear astrophysics: 4He was one of the earliest elements produced in the Big Bang, it is one of the most abundant elements in the universe, and helium burning -- in particular, the triple-alpha process -- is one of the most important ``engines'' in stars. To better understand nucleosynthesis and stellar burning, then, it is important …

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Millimeter-Wavelength Characterization Of The Co Emission Of Comets 174p/Echeclus, 29p/Schwassmann-Wachmann, And C/2016 R2 (Panstarrs), Kacper Wierzchos Nov 2019

Millimeter-Wavelength Characterization Of The Co Emission Of Comets 174p/Echeclus, 29p/Schwassmann-Wachmann, And C/2016 R2 (Panstarrs), Kacper Wierzchos

USF Tampa Graduate Theses and Dissertations

Comets are fascinating minor solar system bodies. They contain some of the most pristine and unprocessed material found in the solar system. As a comet approaches the Sun it displays the characteristic cometary coma and tail. This is due to the release of volatile species through a variety of processes. In the present work I studied the carbon monoxide emission of three very unique comets; 174P/Echeclus, 29P/Schwassmann-Wachmann and C/2016 R2 (PanSTARRS) with different radio telescopes at millimeter wavelengths. After molecular hydrogen, carbon monoxide is the second most abundant molecule in the universe, and is also the most volatile of the …

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