Astrophysics and Astronomy Commons^™

The Similarity Of Broad Iron Lines In X-Ray Binaries And Active Galactic Nuclei, D. J. Walton, R. C. Reis, E. M. Cackett, A. C. Fabian, J. M. Miller

Physics and Astronomy Faculty Research Publications

We have compared the 2001 XMM-Newton spectra of the stellar mass black hole binary XTE J1650-500 and the active galaxy MCG-6-30-15, focusing on the broad, excess emission features at ˜4-7 keV displayed by both sources. Such features are frequently observed in both low-mass X-ray binaries and active galactic nuclei (AGN). For the former case it is generally accepted that the excess arises due to iron emission, but there is some controversy over whether their width is partially enhanced by instrumental processes, and hence also over the intrinsic broadening mechanism. Meanwhile, in the latter case, the origin of this feature is …

Optimization Of The Veritas Orbit-Mode Tracking Pattern, Joshua Allen

Physics

Gamma-ray Bursts (GRBs) have not been detected at TeV energies. Detection with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) would open a new window into GRB science. In this paper, we optimize an orbit mode tracking method to search for a GRB at a location provided by the FERMI Gamma-ray satellite. Using Matlab we modeled the orbit tracking pattern. Then we found the optimal offset radii and tracking speed for the telescope to form a uniform image exposure. To optimize the pattern, the model accounts for the maximum 1°/s speed of the telescope’s tracking motors and the camera’s …

X-Ray Emission Line Profiles From Wind Clump Bow Shocks In Massive Stars., R. Ignace, W. Waldron, J. Cassinelli, A. Burke

ETSU Faculty Works

The consequences of structured flows continue to be a pressing topic in relating spectral data to physical processes occurring in massive star winds. In a preceding paper, our group reported on hydrodynamic simulations of hypersonic flow past a rigid spherical clump to explore the structure of bow shocks that can form around wind clumps. Here we report on profiles of emission lines that arise from such bow shock morphologies. To compute emission line profiles, we adopt a two-component flow structure of wind and clumps using two “beta” velocity laws. While individual bow shocks tend to generate double-horned emission line profiles, …

Late-Time Optical Emission From Core-Collapse Supernovae, Dan Milisavljevic, Robert A. Fesen, Roger A. Chevalier, Robert P. Kirshner

Dartmouth Scholarship

Ground-based optical spectra and Hubble Space Telescope images of 10 core-collapse supernovae (CCSNe) obtained several years to decades after outburst are analyzed with the aim of understanding the general properties of their late-time emissions. New observations of SN 1957D, 1970G, 1980K, and 1993J are included as part of the study. Blueshifted line emissions in oxygen and/or hydrogen with conspicuous line substructure are a common and long-lasting phenomenon in the late-time spectra. Followed through multiple epochs, changes in the relative strengths and velocity widths of the emission lines are consistent with expectations for emissions produced by interaction between SN ejecta and …

Parker Winds Revisited: An Extension To Disk Winds, Timothy Waters

UNLV Theses, Dissertations, Professional Papers, and Capstones

A simple 1D dynamical model of thermally driven disk winds is proposed, based on the results of recent, 2.5D axi-symmetric simulations. Our formulation of the disk wind problem is in the spirit of the original Parker (1958) and Bondi (1952) problems, namely we assume an elementary flow configuration consisting of an outflow following pre-defined trajectories in the presence of a central gravitating point mass. Viscosity and heat conduction are neglected. We consider two different streamline geometries, both comprised of straight lines in the (x,z)-plane: (i) streamlines that converge to a geometric point located at (x,z)=(0,-d) and (ii) streamlines that emerge …

Synthesis And Upconversion Spectroscopy Of Yb Er Doped M2o2s (M = La, Gd, Y) Phosphors, G. A. Kumar, Madhab Pokhrel, Dhiraj K. Sardar, Alejandrina Martinez

Physics & Astronomy Faculty Publications

Yb and Er doped M2O2S (M = Y, Gd, La) phosphor was synthesized by solid state flux fusion method and their up conversion spectral properties were studied as a function different Yb concentrations. The solid state flux fusion results in well crystallized hexagonal shaped phosphor particles of average size 4–6 μm. Upconversion spectral studies shows that all the compositions are stronger in green emission with the green emission intensity 1.7 times than the red in composition Gd2O2S:Yb(8)Er(1), Y2O2S:Yb(9)Er(1), La2O2S:Yb(3)Er(7) (All mol%). The internal upconversion efficiency for the green emission bands was calculated to be 74, 62, 100% respectively in …

Exploring The Possibility Of Floating Orbits For Extreme Mass Ratio Binary Black Holes, Shasvath Jagat Kapadia

Graduate Theses and Dissertations

A binary black hole system, where each black hole orbits the system's center of mass, loses energy by emission of gravitational waves. This causes both black holes to spiral in towards each other. However, if the binary were to, by some mechanism, gain orbital energy at the same rate that it radiates away this energy, a non-decaying or “floating” orbit would result. The thesis uses superradiant scattering and tidal friction, which are two equivalent ways of looking at a process by which the system can gain orbital energy from the spin energy of either black hole, to determine the possibility …

Modeling Water Stability And Transport On Mars And Iapetus: Exploring Their Effects On Geomorphic And Atmospheric Processes, Edgard Giovanni Rivera-Valentin

Graduate Theses and Dissertations

The stability and transport of water on solid planetary surfaces strongly affects both atmospheric and surfaces processes. In this work, two bodies are specifically investigated where transport of water is relevant: Iapetus and Mars. Iapetus, an icy Kronian satellite, has a drastic albedo contrast on its surface and one of the darkest surfaces in the solar system. This extreme brightness contrast is suggested to occur via the transport of water ice from the leading hemisphere to the trailing hemisphere and the poles. Here a global heat and mass transfer model is developed for Iapetus in order to study the current …

Experimental Simulations Of Dark Slope Streaks On Mars, Kelly Howe

Graduate Theses and Dissertations

Martian slope streaks were first observed in Viking images but their formation still remains ambiguous. Martian slope streaks are currently occurring geological phenomenon on Mars, which requires any formation theory to be in agreement with Mar's current temperature and pressure conditions. Planar morphology of martian slope streaks suggest a potential fluvial formation, but current conditions on Mars are not conducive to water remaining liquid long enough to erode the surface. Debris flows, fluid stains and dry dust avalanches have all been previously cited as a potential formation mechanism for martian slope streaks. Recent experimental simulations indicate that a fluvial source …

Book Review: Astronomy At The Frontiers Of Science, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Astronomy at the Frontiers of Science, edited by Jean-Pierre Lasota, Springer, 2011. 357p, 9789400716575 $179.00.

Herschel/Spire Observations Of The Dusty Disk Of Ngc 4244., Benne W. Holwerda, S. Bianchi, T. Boker, D. Radburn-Smith, R. S. De Jong, M. Baes, P. C. Van Der Kruit, M. Xilouris, K. D. Gordon, J. J. Dalcanton

Faculty and Staff Scholarship

We present Herschel/SPIRE images at 250, 350, and 500 μm of NGC 4244, a typical low-mass, disk-only and edge-on spiral galaxy. The dust disk is clumpy and shows signs of truncation at the break radius of the stellar disk. This disk coincides with the densest part of the Hi disk. We compare the spectral energy distribution (SED), including the new SPIRE fluxes, to 3D radiative transfer models; a smooth model disk and a clumpy model with embedded heating. Each model requires a very high value for the dust scale-length (hd = 2−5 h∗), higher dust masses than previous models of …

Absolute Properties Of The Eclipsing Binary Star Bf Draconis, Claud H. Sandberg Lacy, Guillermo Torres, Francis C. Fekel, Jeffrey A. Sabby, Antonio Claret

Information Systems and Engineering Management Research Publications

BF Dra is now known to be an eccentric double-lined F6+F6 binary star with relatively deep (0.7 mag) partial eclipses. Previous studies of the system are improved with 7494 differential photometric observations from the URSA WebScope and 9700 from the NFO WebScope, 106 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope and the 1 m coudé-feed spectrometer at Kitt Peak National Observatory, and 31 accurate radial velocities from the CfA. Very accurate (better than 0.6%) masses and radii are determined from analysis of the two new light curves and four radial velocity curves. Theoretical models …

Hadamard Renormalization Of The Stress Energy Tensor In A Spherically Symmetric Black Hole Space-Time With An Application To Lukewarm Black Holes, Cormac Breen, Adrian Ottewill

Articles

We consider a quantum field which is in a Hartle-Hawking state propagating in a spherically symmetric black hole space-time. We calculate the components of the stress tensor, renormalized using the Hadamard form of the Green's function, in the exterior region of this space-time. We then specialize these results to the case of the `lukewarm' Riessner-Nordstrom-de Sitter black hole.

Search For Gravitational Waves From Low Mass Compact Binary Coalescence In Ligo’S Sixth Science Run And Virgo’S Science Runs 2 And 3, J. Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, R. Adhikari, C. Affeldt, M. Agathos, P. Ajith, B. Allen, G. S. Allen, E. Amador Ceron, D. Amariutei, R. S. Amin, S. B. Anderson, W. G. Anderson, K. Arai, M. A. Arain, M. C. Araya, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, S. Babak, P. Baker, G. Ballardin, Tiffany Z. Summerscales

Faculty Publications

We report on a search for gravitational waves from coalescing compact binaries using LIGO and Virgo observations between July 7, 2009, and October 20, 2010. We searched for signals from binaries with total mass between 2 and 25M this includes binary neutron stars, binary black holes, and binaries consisting of a black hole and neutron star. The detectors were sensitive to systems up to 40 Mpc distant for binary neutron stars, and further for higher mass systems. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass, including …

Probing The Haze In The Atmosphere Of Hd 189733b With Hubble Space Telescope/Wfc3 Transmission Spectroscopy, Neale P. Gibson, Suzanne Aigrain, Frederic Pont, David K. Sing, Jean-Michel Désert, Thomas M. Evans, Gregory W. Henry, Nawal Husnoo, Heather Knutson

Information Systems and Engineering Management Research Publications

We present Hubble Space Telescope near-infrared transmission spectroscopy of the transiting exoplanet HD 189733b, using the Wide Field Camera 3 (WFC3). This consists of time series spectra of two transits, used to measure the wavelength dependence of the planetary radius. These observations aim to test whether the Rayleigh scattering haze detected at optical wavelengths extends into the near-infrared, or if it becomes transparent leaving molecular features to dominate the transmission spectrum. Due to saturation and non-linearity affecting the brightest (central) pixels of the spectrum, light curves were extracted from the blue and red ends of the spectra only, corresponding to …

The Final Journey Of The Saturn V, Andrew R. Thomas, Paul N. Thomarios

University of Akron Press Publications

The Saturn V rocket carried men to the moon, and its history reflects the US space program's rise, success, and demise. In 1961, John F. Kennedy challenged America to put a man on the moon and win the space race. Neil Armstrong set foot on the moon in 1969 in the culmination of a concerted scientific and technological effort.

A little over a decade later, the Saturn rocket was tossed aside to rot in a field near the Kennedy Space Center in Florida. The rocket's carcass became the home to flora and fauna. Like the space program itself, the rocket …

In An Expanding Universe, What Doesn’T Expand?, Richard H. Price, Joseph D. Romano

Physics & Astronomy Faculty Publications

The expansion of the universe is often viewed as a uniform stretching of space that would affect compact objects such as atoms and stars, as well as the separation of galaxies. One usually hears that bound systems do not take part in the general expansion, but a much more subtle question is whether bound systems expand partially. In this paper, a definitive answer is given for a very simple system: a classical “atom” bound by electrical attraction. With a mathematical description appropriate for undergraduate physics majors, we show that this bound system either completely follows the cosmological expansion, or, after …

Spitzer Imaging And Spectral Mapping Of The Oxygen-Rich Supernova Remnant G292.0+1.8, Parviz Ghavamian, Knox S. Long, William P. Blair, Sangwook Park, Robert Fesen

Dartmouth Scholarship

We present mid-infrared continuum and emission line images of the Galactic oxygen-rich supernova remnant (SNR) G292.0+1.8, acquired using the MIPS and IRS instruments on the Spitzer Space Telescope. The MIPS 24 μm and 70 μm images of G292.0+1.8 are dominated by continuum emission from a network of filaments encircling the SNR. The morphology of the SNR, as seen in the mid-infrared, resembles that seen in X-rays with the Chandra X-Ray Observatory. Most of the mid-infrared emission in the MIPS images is produced by circumstellar dust heated in the non-radiative shocks around G292.0+1.8, confirming the results of earlier mid-IR …

Observations Of Ellipsoidal Variations In The Lmxb V1727 Cygni, Alex Price^, Edward L. Robinson, Paul A. Mason*

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Optical Photometry Of The Black Hole Candidate Swift J1753.4-0126, Aurelio Paez^, Edward L. Robinson, Amanda J. Bayless, Paul A. Mason*

COURI Symposium Abstracts, Spring 2012

No abstract provided.