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Full-Text Articles in Physics

Introduction To Classical Field Theory, Charles G. Torre Aug 2019

Introduction To Classical Field Theory, Charles G. Torre

All Complete Monographs

This is an introduction to classical field theory. Topics treated include: Klein-Gordon field, electromagnetic field, scalar electrodynamics, Dirac field, Yang-Mills field, gravitational field, Noether theorems relating symmetries and conservation laws, spontaneous symmetry breaking, Lagrangian and Hamiltonian formalisms.


Gravity Waves Over Antarctica, Vanessa Chambers May 2018

Gravity Waves Over Antarctica, Vanessa Chambers

Physics Capstone Project

As part of the international Antarctic Gravity Wave Instrument Network (ANGWIN) program, the Utah State University all sky IR imager has been operated at the British Antarctic Survey (BAS) Halley Station (75°36′ S, 26°12′ W) since 2012, obtaining valuable gravity wave information in the upper mesosphere and lower thermosphere region (~80 to 100 km). In this study, we have utilized a new 3D spectral analysis technique (Matsuda, et al., 2014) to quantify the horizontal phase velocity distributions of gravity waves over Antarctica. This new tool enables us to analyze extensive amounts of airglow imaging data in a relatively ...


Does The Black Hole Shadow Probe The Event Horizon Geometry?, Pedro V. P. Cunha, Carlos A. R. Herdeiro, Maria J. Rodriguez Apr 2018

Does The Black Hole Shadow Probe The Event Horizon Geometry?, Pedro V. P. Cunha, Carlos A. R. Herdeiro, Maria J. Rodriguez

All Physics Faculty Publications

There is an exciting prospect of obtaining the shadow of astrophysical black holes (BHs) in the near future with the Event Horizon Telescope. As a matter of principle, this justifies asking how much one can learn about the BH horizon itself from such a measurement. Since the shadow is determined by a set of special photon orbits, rather than horizon properties, it is possible that different horizon geometries yield similar shadows. One may then ask how sensitive is the shadow to details of the horizon geometry? As a case study, we consider the double Schwarzschild BH and analyze the impact ...


Introduction To The Usu Library Of Solutions To The Einstein Field Equations, Ian M. Anderson, Charles G. Torre Dec 2017

Introduction To The Usu Library Of Solutions To The Einstein Field Equations, Ian M. Anderson, Charles G. Torre

Tutorials on... in 1 hour or less

This is a Maple worksheet providing an introduction to the USU Library of Solutions to the Einstein Field Equations. The library is part of the DifferentialGeometry software project and is a collection of symbolic data and metadata describing solutions to the Einstein equations.


How Hospitable Are Space Weather Affected Habitable Zones? The Role Of Ion Escape, Vladimir S. Airapetian, Alex Glocer, George V. Khazanov, Robert O Parke Loyd, Kevin France, Ján J. Sojka, William C. Danchi, Michael W. Liemohn Feb 2017

How Hospitable Are Space Weather Affected Habitable Zones? The Role Of Ion Escape, Vladimir S. Airapetian, Alex Glocer, George V. Khazanov, Robert O Parke Loyd, Kevin France, Ján J. Sojka, William C. Danchi, Michael W. Liemohn

All Physics Faculty Publications

Atmospheres of exoplanets in the habitable zones around active young G-K-M stars are subject to extreme X-ray and EUV (XUV) fluxes from their host stars that can initiate atmospheric erosion. Atmospheric loss affects exoplanetary habitability in terms of surface water inventory, atmospheric pressure, the efficiency of greenhouse warming, and the dosage of the UV surface irradiation. Thermal escape models suggest that exoplanetary atmospheres around active K-M stars should undergo massive hydrogen escape, while heavier species including oxygen will accumulate forming an oxidizing atmosphere. Here, we show that non-thermal oxygen ion escape could be as important as thermal, hydrodynamic H escape ...


Climatology Of Plasmaspheric Total Electron Content Obtained From Jason 1 Satellite, Ja Soon Shim, Geonhwa Jee, Ludger Scherliess Feb 2017

Climatology Of Plasmaspheric Total Electron Content Obtained From Jason 1 Satellite, Ja Soon Shim, Geonhwa Jee, Ludger Scherliess

All Physics Faculty Publications

We used more than 40 million total electron content (TEC) measurements obtained from the GPS TurboRogue Space Receiver receiver on board the Jason 1 satellite in order to investigate the global morphology of the plasmaspheric TEC (pTEC) including the variations with local time, latitude, longitude, season, solar cycle, and geomagnetic activity. The pTEC corresponds to the total electron content between Jason 1 (1336 km) and GPS (20,200 km) satellite altitudes. The pTEC data were collected during the 7 year period from January 2002 to December 2008. It was found that pTEC increases by about 10–30% from low to ...


The Differentialgeometry Package, Ian M. Anderson, Charles G. Torre Jan 2016

The Differentialgeometry Package, Ian M. Anderson, Charles G. Torre

Downloads

This is the entire DifferentialGeometry package, a zip file (DifferentialGeometry.zip) containing (1) a Maple Library file, DifferentialGeometryUSU.mla, (2) a Maple help file DifferentialGeometry.help. This is the latest version of the DifferentialGeometry software; it supersedes what is released with Maple. It has been tested on Maple versions 17, 18, 2015.

Installation instructions


How Uncertainty In The Neutral Wind Limits The Accuracy Of Ionospheric Modeling And Forecasting, Michael David, Jan J. Sojka, Robert W. Schunk Jan 2016

How Uncertainty In The Neutral Wind Limits The Accuracy Of Ionospheric Modeling And Forecasting, Michael David, Jan J. Sojka, Robert W. Schunk

Publications

One of the most important input fields for an ionospheric model is the horizontal neutral wind. The primary mechanism by which the neutral wind affects ionospheric densities is the inducement of an upward or downward ion drift along the magnetic field lines; this affects the rate at which ions are lost through recombination. The magnitude of this effect depends upon the dip angle of the magnetic field; for this reason, the impact of the neutral wind is somewhat less in polar regions than at mid-latitudes. It is unfortunate that observations of the neutral wind are relatively scarce, as compared for ...


Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos Jul 2015

Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos

Charles G. Torre

Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and electromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equations are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Geometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and formulas for constructing the scalar field from ...


Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos Mar 2015

Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos

Presentations and Publications

Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and elec- tromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equa- tions are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Ge- ometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and for- mulas for constructing ...


Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre Dec 2014

Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre

Research Vignettes

In this worksheet we describe and illustrate a relatively simple set of new Rainich-type conditions on an n-dimensional spacetime which are necessary and sufficient for it to define a perfect fluid solution of the Einstein field equations. Procedures are provided which implement these Rainich-type conditions and which reconstruct the perfect fluid from the metric. These results provide an example of the idea of geometrization of matter fields in general relativity, which is a purely geometrical characterization of matter fields via the Einstein field equations.


Perihelion Precession In General Relativity, Charles G. Torre Apr 2014

Perihelion Precession In General Relativity, Charles G. Torre

Charles G. Torre

This is a Maple worksheet providing a relatively quick and informal sketch of a demonstration that general relativistic corrections to the bound Kepler orbits introduce a perihelion precession. Any decent textbook will derive this result. My analysis aligns with that found in the old text "Introduction to General Relativity", by Adler, Bazin and Schiffer. The plan of the analysis is as follows. * Model the planetary orbits as geodesics in the (exterior) Schwarzschild spacetime. * Compute the geodesic equations. * Simplify them using symmetries and first integrals. * Isolate the differential equation expressing the radial coordinate as a function of orbital angle - the "equation ...


The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre Feb 2014

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Charles G. Torre

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from ...


Annual Solar Motion And Spy Satellites, Margaret Jensen, Shane L. Larson Jan 2014

Annual Solar Motion And Spy Satellites, Margaret Jensen, Shane L. Larson

Browse All Undergraduate research

A topic often taught in introductory astronomy courses is the changing position of the Sun in the sky as a function of time of day, and season. The relevance and importance of this motion is explained in the context of seasons and the impact it has on human activities such as agriculture. The geometry of the ob- served motion in the sky is usually reduced to graphical representations and visualizations that can be difficult to render and grasp. Sometimes students are asked to observe the Suns changing motion and record their data, but this is a long-term project requiring several ...


Rainich-Type Conditions For Null Electrovacuum Spacetimes Ii, Charles G. Torre Oct 2013

Rainich-Type Conditions For Null Electrovacuum Spacetimes Ii, Charles G. Torre

Research Vignettes

In this second of two worksheets I continue describing local Rainich-type conditions which are necessary and sufficient for the metric to define a null electrovacuum. In other words, these conditions, which I will call the null electrovacuum conditions, guarantee the existence of a null electromagnetic field such that the metric and electromagnetic field satisfy the Einstein-Maxwell equations. When it exists, the electromagnetic field is easily constructed from the metric. In this worksheet I consider the null electrovacuum conditions which apply when a certain null geodesic congruence determined by the metric is twisting. I shall illustrate the these conditions using a ...


Understanding Light Pollution In And Around Tucson, Arizona, Rachel K. Nydegger Aug 2013

Understanding Light Pollution In And Around Tucson, Arizona, Rachel K. Nydegger

Browse All Undergraduate research

No abstract provided.


The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre Jul 2013

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Presentations and Publications

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from ...


How To Find Killing Vectors, Charles G. Torre Mar 2013

How To Find Killing Vectors, Charles G. Torre

How to... in 10 minutes or less

We show how to compute the Lie algebra of Killing vector fields of a metric in Maple using the commands KillingVectors and LieAlgebraData. A Maple worksheet and a PDF version can be found below.


Prospects For Observing Ultracompact Binaries With Space-Based Gravitational Wave Interferometers And Optical Telescopes., T. B. Littenberg, Shane Larson, G. Nelemans Department Of Astrophysics, Radboud University Nijmegen, N. J. Cornish Mar 2013

Prospects For Observing Ultracompact Binaries With Space-Based Gravitational Wave Interferometers And Optical Telescopes., T. B. Littenberg, Shane Larson, G. Nelemans Department Of Astrophysics, Radboud University Nijmegen, N. J. Cornish

All Physics Faculty Publications

Space-based gravitational wave interferometers are sensitive to the galactic population of ultra-compact binaries. An important subset of the ultra-compact binary popula- tion are those stars that can be individually resolved by both gravitational wave in- terferometers and electromagnetic telescopes. The aim of this paper is to quantify the multi-messenger potential of space-based interferometers with arm-lengths between 1 and 5 Gm. The Fisher Information Matrix is used to estimate the number of binaries from a model of the Milky Way which are localized on the sky by the gravitational wave detector to within 1 and 10 deg2 and bright enough to ...


Characterizing Sky Variability For Multi-Messenger Astronomy, Rachel Nydegger Feb 2013

Characterizing Sky Variability For Multi-Messenger Astronomy, Rachel Nydegger

UCUR

Multi-messenger astronomy employs both electromagnetic and gravitational -wave detectors to paint a richer picture of celestial objects, providing more depth and information. The interferometers utilized for gravitational-wave observations receive input from very broad fields of view on the sky, typically a few square degrees. To have simultaneous electromagnetic observations (typically less than one square degree) requires innovative techniques for the telescopes to find the origin of radiation. One idea is to “tile” the view of the interferometer, using multiple telescopes to simultaneously point at different areas of the field to observe the source. One di"culty of this observing paradigm ...


Mapping Light Pollution At Utah State University, Rachel Nydegger, Shane L. Larson Jan 2013

Mapping Light Pollution At Utah State University, Rachel Nydegger, Shane L. Larson

Research on the Hill (Salt Lake City)

One of the beauties of modern civilization is seeing the city lighting at night. It provides a feeling of security and is indicative of the power and endeavors of humanity, but over-lighting is a form of pollution. Many outdoor light fixtures spread light in all directions, sending a majority of the light into the sky, away from where we want the light to be on the ground. This light spreading upward is not only wasted light, but it is wasted energy and money, destroys our ability to view the night sky, and has profound effects on nocturnal creatures. The direct ...


Galaxy Inclination And Surface Brightness, Jordan C. Rozum, Shane L. Larson Jan 2013

Galaxy Inclination And Surface Brightness, Jordan C. Rozum, Shane L. Larson

Student Showcase

The distribution of spiral and bar galaxy inclination angles is expected to be uniform. However, analysis of several major galaxy catalogs shows this is not the case; galaxies oriented near edge-on are significantly more common in these catalogs. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and interstellar medium (ISM) density distributions. The luminous mass component is integrated along a particular line ...


Modeling Spiral Galaxy Luminosity Profiles, Jordan Rozum, Matt Garlock, Shane L. Larson, Bradley W. Carroll Oct 2012

Modeling Spiral Galaxy Luminosity Profiles, Jordan Rozum, Matt Garlock, Shane L. Larson, Bradley W. Carroll

Browse All Undergraduate research

The distribution of spiral and bar galaxy inclination an- gles is expected to be uniform. However, analysis of sev- eral major galaxy catalogs shows this is not the case; galaxies oriented near edge-on are significantly more common in these catalogs. In an attempt to explain this discrepancy, we have developed a galaxy simulation code to compute the appearance of a spiral type galaxy as a function of its morphological parameters. We examine the dependence of observed brightness upon inclination angle by using smooth luminous mass density and in- terstellar medium (ISM) density distributions. The lu- minous mass component is integrated ...


Constraining The Black Hole Mass Spectrum With Gravitational Wave Observations – I. The Error Kernel, Danny C. Jacobs, Joseph E. Plowman, Ronald W. Hellings, Sachiko Tsuruta, Shane L. Larson Feb 2010

Constraining The Black Hole Mass Spectrum With Gravitational Wave Observations – I. The Error Kernel, Danny C. Jacobs, Joseph E. Plowman, Ronald W. Hellings, Sachiko Tsuruta, Shane L. Larson

All Physics Faculty Publications

Many scenarios have been proposed for the origin of the supermassive black holes (SMBHs) that are found in the centres of most galaxies. Many of these formation scenarios predict a high-redshift population of intermediate-mass black holes (IMBHs), with masses M in the range 102M≲ 105 M. A powerful way to observe these IMBHs is via gravitational waves the black holes emit as they merge. The statistics of the observed black hole population should, in principle, allow us to discriminate between competing astrophysical scenarios for the origin and formation of SMBHs. However, gravitational wave detectors such as Laser ...


Detecting A Stochastic Gravitational-Wave Background: The Overlap Reduction Function, Lee Samuel Finn, Shane L. Larson, Joseph D. Romano Jan 2009

Detecting A Stochastic Gravitational-Wave Background: The Overlap Reduction Function, Lee Samuel Finn, Shane L. Larson, Joseph D. Romano

All Physics Faculty Publications

Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross correlation of the response of two or more independent detectors. The cross correlation involves a frequency-dependent factor—the so-called overlap reduction function or Hellings-Downs curve—that depends on the relative geometry of each detector pair, i.e., the detector separations and the relative orientation of their antenna patterns (beams). An incorrect formulation of this geometrical factor has appeared in the literature, leading to incorrect conclusions regarding the sensitivity of proposed detectors to a stochastic gravitational-wave background. To rectify these errors and as a reference for ...


The Adaptability Of Langmuir Probes To The Pico-Satellite Regime, Andrew Jay Auman Dec 2008

The Adaptability Of Langmuir Probes To The Pico-Satellite Regime, Andrew Jay Auman

All Graduate Theses and Dissertations

The purpose of this thesis is to investigate whether it is feasible to use Langmuir probes on pico-satellites flying in low Earth orbit over mid- to low-latitude geographic regions. Following chapters on the expected ionospheric conditions and an overview of Langmuir probe theory, a chapter addressing the difficulties involved with pico-satellite Langmuir probes is presented. Also, the necessary satellite-to-probe surface area requirements in order to achieve confidence in pico-satellite Langmuir probe data, for the orbital regions of interest to this thesis, are stated.


Gravitational Wave Bursts From The Galactic Massive Black Hole, Clovis Hopman, Marc Freitag, Shane L. Larson Jun 2007

Gravitational Wave Bursts From The Galactic Massive Black Hole, Clovis Hopman, Marc Freitag, Shane L. Larson

All Physics Faculty Publications

The Galactic massive black hole (MBH), with a mass of M= 3.6 × 106 M, is the closest known MBH, at a distance of only 8 kpc. The proximity of this MBH makes it possible to observe gravitational waves (GWs) from stars with periapse in the observational frequency window of the Laser Interferometer Space Antenna (LISA). This is possible even if the orbit of the star is very eccentric, so that the orbital frequency is many orders of magnitude below the LISA frequency window, as suggested by Rubbo, Holley-Bockelmann & Finn (2006). Here we give an analytical estimate of the ...


Semi-Relativistic Approximation To Gravitational Radiation From Encounters With Non-Spinning Black Holes, Jonathan R. Gair, Daniel J. Kennefick, Shane L. Larson Jan 2005

Semi-Relativistic Approximation To Gravitational Radiation From Encounters With Non-Spinning Black Holes, Jonathan R. Gair, Daniel J. Kennefick, Shane L. Larson

All Physics Faculty Publications

The capture of compact bodies by black holes in galactic nuclei is an important prospective source for low frequency gravitational wave detectors, such as the planned Laser Interferometer Space Antenna. This paper calculates, using a semirelativistic approximation, the total energy and angular momentum lost to gravitational radiation by compact bodies on very high eccentricity orbits passing close to a supermassive, nonspinning black hole; these quantities determine the characteristics of the orbital evolution necessary to estimate the capture rate. The semirelativistic approximation improves upon treatments which use orbits at Newtonian order and quadrupolar radiation emission, and matches well onto accurate Teukolsky ...


Lisa Time-Delay Interferometry Zero-Signal Solution: Geometrical Properties, Massimo Tinto, Shane L. Larson Jan 2004

Lisa Time-Delay Interferometry Zero-Signal Solution: Geometrical Properties, Massimo Tinto, Shane L. Larson

All Physics Faculty Publications

Time-delay interferometry (TDI) is the data processing technique needed for generating interferometric combinations of data measured by the multiple Doppler readouts available onboard the three Laser Interferometer Space Antenna (LISA) spacecraft. Within the space of all possible interferometric combinations TDI can generate, we have derived a specific combination that has zero response to the gravitational wave signal, and called it the zero-signal solution (ZSS). This is a two-parameter family of linear combinations of the generators of the TDI space, and its response to a gravitational wave becomes null when these two parameters coincide with the values of the angles of ...


Lisa Data Analysis: Source Identification And Subtraction, Neil J. Cornish, Shane L. Larson Jan 2003

Lisa Data Analysis: Source Identification And Subtraction, Neil J. Cornish, Shane L. Larson

All Physics Faculty Publications

The Laser Interferometer Space Antenna will operate as an AM-FM receiver for gravitational waves. For binary systems, the source location, orientation and orbital phase are encoded in the amplitude and frequency modulation. The same modulations spread a monochromatic signal over a range of frequencies, making it difficult to identify individual sources. We present a method for detecting and subtracting individual binary signals from a data stream with many overlapping signals.