Astrophysics and Astronomy Commons^™

Minisuperspace Canonical Quantization Of The Reissner-Nordström Black Hole Via Conditional Symmetries, T. Christodoulakis, Nicholas Dimakis, Petros A. Terzis, Babak Vakili, E. Melas, Th. Grammenos

Physics & Astronomy Faculty Publications

We use the conditional symmetry approach to study the r evolution of a minisuperspace spherically symmetric model both at the classical and the quantum level. After integration of the coordinates t, θ and ϕ in the gravitational plus electromagnetic action the configuration space dependent dynamical variables turn out to correspond to the r-dependent metric functions and the electrostatic field. In the context of the formalism for constrained systems (Dirac-Bergmann, Arnowitt-Deser-Misner) with respect to the radial coordinate r, we set up a pointlike reparametrization invariant Lagrangian. It is seen that, in the constant potential parametrization of the lapse, the corresponding minisuperspace …

Spot Activity Of The Rs Canum Venaticorum Star Σ Geminorum, Perttu Kajatkari, Thomas Hackman, Lauri Jetsu, Jyri J. Lehtinen, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Aims. We model the photometry of RS CVn star σ Geminorum to obtain new information on the changes of the surface starspot distribution, that is, activity cycles, differential rotation, and active longitudes.

Methods. We used the previously published continuous period search (CPS) method to analyse V-band differential photometry obtained between the years 1987 and 2010 with the T3 0.4 m Automated Telescope at the Fairborn Observatory. The CPS method divides data into short subsets and then models the light-curves with Fourier-models of variable orders and provides estimates of the mean magnitude, amplitude, period, and light-curve minima. These light-curve parameters …

Preventing Asteroid Impact By Deflection: A Numerical Simulation, Rebecca J. Carlson

Journal of Undergraduate Research

Small objects from outer space collide with the earth’s atmosphere every day. Most of these are small enough to burn up completely before hitting the ground. A few, however, reach the earth’s surface as meteorites. On occasion, an asteroid large enough to cause serious darnage impacts the earth. Although impacts large enough to destroy cities only occur once in a thousand years or so, if such an event were to occur there would be great loss of life and damage of property (Rather 1992). Because of this, it is important to develop plans to deter an asteroid on a colllslon …

Pioneer Venus Orbiter Retarding Potential Analyzer Observations Of The Electron Component Of The Solar Wind And Observations Of Venus Bow Shock Crossings And The Magnetosheath Region, Noe Yamaguchi

Journal of Undergraduate Research

A bow shock is a paraboloid-shaped shockwave that forms around a planet similar to one that forms around an airplane traveling faster than the speed of sound. We may observe this shock by the change in plasma parameters before and after entering the bow shock. Those plasma parameters include temperature, density, pressure, velocity, magnetic field and others.

Tracing The Evolution Of Active Galactic Nuclei Host Galaxies Over The Last 9 Gyr Of Cosmic Time, A. D. Goulding, W. R. Forman, R. C. Hickox, C. Jones

Dartmouth Scholarship

We present the results of a combined galaxy population analysis for the host galaxies of active galactic nuclei (AGN) identified at 0 < z < 1.4 within the Sloan Digital Sky Survey, Boötes, and DEEP2 surveys. We identified AGN in a uniform and unbiased manner at X-ray, infrared, and radio wavelengths. Supermassive black holes undergoing radiatively efficient accretion (detected as X-ray and/or infrared AGN) appear to be hosted in a separate and distinct galaxy population than AGN undergoing powerful mechanically dominated accretion (radio AGN). Consistent with some previous studies, radiatively efficient AGN appear to be preferentially hosted in modest star-forming galaxies, with little dependence on AGN or galaxy luminosity. AGN exhibiting radio-emitting jets due to mechanically dominated accretion are almost exclusively observed in massive, passive galaxies. Crucially, we now provide strong evidence that the observed host-galaxy trends are independent of redshift. In particular, these different accretion-mode AGN have remained as separate galaxy populations throughout the last 9 Gyr. Furthermore, it appears that galaxies hosting AGN have evolved along the same path as galaxies that are not hosting AGN with little evidence for distinctly separate evolution.

First Searches For Optical Counterparts To Gravitational-Wave Candidate Events, M. Constancio, J. Aasi, J. Abadie, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano

Physics & Astronomy Faculty Publications

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers …

First Searches For Optical Counterparts To Gravitational-Wave Candidate Events, Tiffany Summerscales, Ligo Scientific Collaboration And Virgo Collaboration

Faculty Publications

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers …

Welcome And Opening Remarks, Rick C. Chappell

Magnetospheric-Ionospheric Coupling Conference

No abstract provided.

A Three-Year Multi-Wavelength Study Of The Very-High-Energy Gamma-Ray Blazar 1es 0229+200, P. T. Reynolds, Et. Al.

Physical Sciences Publications

The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Γ ~ 2.5), very-high-energy (VHE; E > 100 GeV) emitting γ-ray blazar. VHE measurements of this active galactic nucleus have been used to place constraints on the intensity of the extragalactic background light and the intergalactic magnetic field (IGMF). A multi-wavelength study of this object centered around VHE observations by Very Energetic Radiation Imaging Telescope Array System (VERITAS) is presented. This study obtained, over a period of three years, an 11.7 standard deviation detection and an average integral flux F(E > 300 GeV) = (23.3 ± 2.8stat …

Study Of The Eclipsing Binary Ah Cancri, Delora Chere' Tanner, Dr. Benjamin Taylor

Journal of Undergraduate Research

Unlike research in many other disciplines, astronomical research is highly dependent upon the weather. My original proposed research was to further the task of calibrating standard stars in the M67 open cluster. Unfortunately the weather was unfavorable during the window of time that this cluster was available for viewing, therefore, I could not secure the amount of data needed to conduct my proposed research. I decided to change the focus of my research to an individual star located in M67, AH Cancri. I was able to use raw archive data of the M67 star field to study this star.

Scalar Waves Scattering Off A Cylinder, David Oliphant, Dr. R. Steven Turley

Journal of Undergraduate Research

Scattering problems are common in physics. A scattered (reflected) wave or particle from an object can give us hints to the nature of the object’s shape, size, color, or composition. This is the basic principle behind sonar, radar, ultrasound, NMR, and even vision. One technique in determining the nature of a scattered wave is called the Method of Moments. It involves solving the Helmholtz equation by representing the object’s response or current as a sum of basis functions and weights. The number of basis functions used is important. If there are too many the computational time becomes inordinate. However, there …

Extreme Ultraviolet Ellipsometry, Spencer E. Olson, Dr. R. Steven Turley

Journal of Undergraduate Research

Ellipsometry, a common technique used with visible light, measures the change of the state of polarization as it reflect off a material. By so doing, the way that light interacts with materials can be understood more clearly. Also, optical properties, known as the index of refraction and absorption coefficient, can be found from this technique. With these known optical properties of various materials, elements, such as mirrors and polarizers, can be optimized for optical instruments. The name ellipsometry comes from the fact that the technique is based on the analysis of what is called ellipsometrically polarized light. For the simple …

Semiclassical Quantization: Corrections And Causes, Teresa Griffin

Journal of Undergraduate Research

My research over the past six months has produced a method of understanding the differences between semiclassical approximation methods and the exact quantum results.

Work Towards Building An Extreme Ultraviolet Ellipsometer, Cort N. Johnson, Dr. David D. Allred

Journal of Undergraduate Research

The extreme ultraviolet (EUV) optics group at Brigham Young University uses thin film technology to develop multiplayer mirrors and designed to reflect well at certain EUV wavelengths. We need methods of measuring layer thickness on the order of a few angstroms. One method often used in thin film sample analysis is ellipsometry.

Interaction Between The Broad-Lined Type Ic Supernova 2012ap And Carriers Of Diffuse Interstellar Bands, Dan Milisavljevic, Raffaella Margutti, Kyle N. Crabtree, Jonathan B. Foster, Alicia M. Soderberg, Robert A. Fesen, Jerod T. Parrent

Dartmouth Scholarship

Diffuse interstellar bands (DIBs) are absorption features observed in optical and near-infrared spectra that are thought to be associated with carbon-rich polyatomic molecules in interstellar gas. However, because the central wavelengths of these bands do not correspond to electronic transitions of any known atomic or molecular species, their nature has remained uncertain since their discovery almost a century ago. Here we report on unusually strong DIBs in optical spectra of the broad-lined Type Ic supernova SN 2012ap that exhibit changes in equivalent width over short ( 30 days) timescales. The 4428 Å and 6283 Å DIB features get weaker with …

Two-Neutron Transfer Reaction Mechanisms In 12C(6He, 4He) 14C Using A Realistic Three-Body 6He Model, D. Smalley, F. Sarazin, F. M. Nunes, B. A. Brown, P. Adsley, H. Al-Falou, C. Andreoiu, B. Baartman, G. C. Ball, J. C. Blackmon, H. C. Boston, W. N. Catford, S. Chagnon-Lessard, A. Chester, R. M. Churchman, D. S. Cross, C. Aa. Diget, D. Di Valentino, S. P. Fox, B. R. Fulton, A. Garnsworthy, G. Hackman, U. Hager, R. Kshetri, J. N. Orce, N. A. Orr, E. Paul, M. Pearson, E. T. Rand, J. Rees, S. Sjue, C. E. Svensson, E. Tardiff, A. Diaz Varela, S. J. Williams, Steven W. Yates

Physics and Astronomy Faculty Publications

The reaction mechanisms of the two-neutron transfer reaction ¹²C(⁶He,⁴He) have been studied at E_lab=30 MeV at the TRIUMF ISAC-II facility using the Silicon Highly-segmented Array for Reactions and Coulex (SHARC) charged-particle detector array. Optical potential parameters have been extracted from the analysis of the elastic scattering angular distribution. The new potential has been applied to the study of the transfer angular distribution to the 2+₂ 8.32 MeV state in ¹⁴C, using a realistic three-body ⁶He model and advanced shell-model calculations for the carbon structure, allowing to calculate the relative contributions …

The Orbits Of The Triple-Star System 1 Geminorum From Phases Differential Astrometry And Spectroscopy, Benjamin F. Lane, Matthew W. Muterspaugh, Roger F. Griffin, Colin D. Scarfe, Francis C. Fekel, Michael H. Williamson, Joel A. Eaton, Michael Shao, Mark M. Colavita, Maciej Konacki

Information Systems and Engineering Management Research Publications

We have used precise differential astrometry from the Palomar High-precision Astrometric Search for Exoplanet Systems project and radial-velocity measurements covering a time span of 40 yr to determine the orbital parameters of the 1 Geminorum triple system. We present the first detection of the spectral lines of the third component of the system, together with precise mass (0.5%) and distance (0.15%) determinations for this system. In addition, our astrometry allows us to make the first determination of the mutual inclination of the orbits.

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 …

Kelt-6b: A P ~ 7.9 Day Hot Saturn Transiting A Metal-Poor Star With A Long-Period Companion, K. A. Collins, J. D. Eastman, T. G. Beatty, R. J. Siverd, B. S. Gaudi, J. Pepper, J. F. Kielkopf, J. A. Johnson, A. W. Howard, D. A. Fischer, M. Manner, A. Bieryla, D. W. Latham, B. J. Fulton, J. Gregorio, L. A. Buchhave, Eric L.N. Jensen, K. G. Stassun, K. Penev, J. R. Crepp, S. Hinkley, R. A. Street, P. Cargile, C. E. Mack, T. E. Oberst, R. L. Avril, S. N. Mellon, K. K. Mcleod, M. T. Penny, R. P. Stefanik, P. Berlind, M. L. Calkins, Q. Mao, A. J.W. Richert, D. L. Depoy, G. A. Esquerdo, A. Gould, J. L. Marshall, R. J. Oelkers, R. W. Pogge, M. Trueblood, P. Trueblood

Physics & Astronomy Faculty Works

We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T _eff = 6102 ± 43 K, log g_\star =4.07_{-0.07}^{+0.04}, and [Fe/H] = -0.28 ± 0.04, with an inferred mass M _sstarf = …

Interaction Of Magnetic Reconnection And Kelvin-Helmholtz Modes For Large Magnetic Shear: 1. Kelvin-Helmholtz Trigger, Xuanye Ma, Antonius Otto, Peter A. Delamere

Publications

At the Earth's magnetopause, both magnetic reconnection and the Kelvin‐Helmholtz (KH) instability can operate simultaneously for southward interplanetary magnetic field conditions. The dynamic evolution of such a system can be expected to depend on the importance of KH wave evolution versus reconnection and therefore on the respective initial perturbations. In this study, a series of local three‐dimensional MHD and Hall MHD simulations are carried out to investigate the situation where the Kelvin‐Helmholtz instability is initially the primary process. It is demonstrated that magnetic reconnection is driven and strongly modified by nonlinear KH waves. The highest reconnection rate is close to …