Hydrogen Two-Photon Continuum Emission From The Horseshoe Filament In Ngc 1275,
2012
University of Cambridge, UK
Hydrogen Two-Photon Continuum Emission From The Horseshoe Filament In Ngc 1275, R. M. Johnstone, R. E.A. Canning, A. C. Fabian, Gary J. Ferland, Matt Lykins, R. L. Porter, P. A.M. Vanhoof, R. J.R. Williams
Physics and Astronomy Faculty Publications
Far-ultraviolet emission has been detected from a knot of Hα emission in the Horseshoe filament, far out in the NGC 1275 nebula. The flux detected relative to the brightness of the Hα line in the same spatial region is very close to that expected from hydrogen two-photon continuum emission in the particle heating model of Ferland et al. if reddening internal to the filaments is taken into account. We find no need to invoke other sources of far-ultraviolet emission such as hot stars or emission lines from C IV in intermediate-temperature gas to explain these data.
Intervening Broad-Line Region Clouds' Effects On The Optical/Ultraviolet Spectrum,
2012
University of Kentucky
Intervening Broad-Line Region Clouds' Effects On The Optical/Ultraviolet Spectrum, Ye Wang, Gary J. Ferland, Chen Hu, Jian-Min Wang, Pu Du
Physics and Astronomy Faculty Publications
Recent X-ray observations of Mrk 766 suggest that broad emission-line region clouds cross our line of sight and produce variable X-ray absorption. Here we investigate what optical/ultraviolet (UV) spectroscopic features would be produced by such ‘intervening broad-line region (BLR) clouds' (IBC) crossing our line of sight to the accretion disc, the source of the optical/UV continuum. Although the emission spectrum produced by intervening clouds is identical to the standard BLR model, they may produce absorption features on the optical or UV continuum. Single clouds will have little effect on the optical/UV spectrum because BLR clouds are likely to be much …
New Methods For The Discovery And Characterization Of Lunar Lava Tubes Using Lunar Reconnaissance Orbiter Data,
2012
University of Texas at El Paso
New Methods For The Discovery And Characterization Of Lunar Lava Tubes Using Lunar Reconnaissance Orbiter Data, Jonathan Arthur Meyer
Open Access Theses & Dissertations
Lava tubes have the potential to serve as a sustainable solution to long-term lunar habitation by providing protection from radiation and micrometeorite bombardment while potentially providing resources in the form of trapped water ice. They also pose compelling science targets in their own right. While the potential benefits of utilizing lunar lava tubes is clear, their discovery is less straightforward. Formation processes for lava tubes do not always result in a surface expression, making their discovery using remotely sensed imagery difficult. Furthermore, there is the potential for lava tubes to be covered by secondary lava flows, impact ejecta, or other …
High-Speed Acousto-Optic Shutter With No Optical Frequency Shift,
2012
Bucknell University
High-Speed Acousto-Optic Shutter With No Optical Frequency Shift, W J. Schwenger, James M. Higbie
Faculty Journal Articles
Acousto-optic modulators are widely used for rapid switching and shuttering of laser beams. In many applications, the concomitant frequency shift is undesirable and must be compensated for elsewhere in the system. Here we present a simple method of achieving rapid laser power switching without an accompanying laser frequency shift. The demonstrated acousto-optic shutter achieves a switching time of around 25 ns, an extinction ratio of 46 dB, and efficiency comparable to a conventional double-pass acousto-optical modulator configuration. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4746292]
Isometries And Spontaneous Lorentz Violation In General Relativity,
2012
Colby College
Isometries And Spontaneous Lorentz Violation In General Relativity, Greg Merritt
Honors Theses
General Relativity, or GR, is a theory which describes gravity as a manifestation of the curvature of space and time. While the other three fundamental forces in nature are represented as field theories, GR is a geometric theory. In the search for a way to reconcile the field theories for the electromagnetic, strong, and weak forces with the gravitational force, a logical place to start is by re-expressing GR as a field theory. In doing so, we find that the theory contains a number of symmetries. When we solve the equations in GR, we find that by choosing certain solutions …
The Late-Time Afterglow Of The Extremely Energetic Short Burst Grb 090510 Revisited,
2012
Roger Williams University
The Late-Time Afterglow Of The Extremely Energetic Short Burst Grb 090510 Revisited, A. Nicuesa Guelbenzu, S. Klose, T. Krühler, J. Greiner, A. Rossi, D.A. Kann, F. Olivares, A. Rau, P.M.J. Afonso, J. Elliott, R. Filgas, A. Küpcü Yoldas, S. Mcbreen, M. Nardini, P. Schady, S. Schmidl, V. Sudilovsky, Adria Updike, A. Yoldas
Arts & Sciences Faculty Publications
No abstract provided.
The Fast Evolution Of Sn 2010bh Associated With Xrf 100316d,
2012
Roger Williams University
The Fast Evolution Of Sn 2010bh Associated With Xrf 100316d, F. Olivares E., J. Greiner, P. Schady, A. Rau, S. Klose, T. Krühler, P.M.J. Afonso, Adria Updike, M. Nardini, R. Filgas, A. Nicuesa Guelbenzu, C. Clemens, J. Elliott, D.A. Kann, A. Rossi, V. Sudilovsky
Arts & Sciences Faculty Publications
No abstract provided.
Bl Lacertae Objects Beyond Redshift 1.3 – Uv-To-Nir Photometry And Photometric Redshift For Fermi/Lat Blazars,
2012
Roger Williams University
Bl Lacertae Objects Beyond Redshift 1.3 – Uv-To-Nir Photometry And Photometric Redshift For Fermi/Lat Blazars, A. Rau, P. Schady, J. Greiner, M. Salvato, M. Ajello, E. Bottacini, N. Gehrels, P.M.J. Afonso, J. Elliott, R. Filgas, D.A. Kann, S. Klose, T. Krühler, M. Nardini, A. Nicuesa Guelbenzu, F. Olivares E., A. Rossi, V. Sudilovsky, Adria Updike, D.H. Hartmann
Arts & Sciences Faculty Publications
Context. Observations of the γ-ray sky with Fermi led to significant advances towards understanding blazars, the most extreme class of active galactic nuclei. A large fraction of the population detected by Fermi is formed by BL Lacertae (BL Lac) objects, whose sample has always suffered from a severe redshift incompleteness due to the quasi-featureless optical spectra. Aims. Our goal is to provide a significant increase of the number of confirmed high-redshift BL Lac objects contained in the 2 LAC Fermi/LAT cataloge.Methods. For 103 Fermi/LAT blazars, photometric redshifts using spectral energy distribution fitting have been obtained.The photometry includes 13 broad-band filters …
Phase Estimation With Two-Mode Squeezed Vacuum And Parity Detection: Bayesian Analysis,
2012
Louisiana State University
Phase Estimation With Two-Mode Squeezed Vacuum And Parity Detection: Bayesian Analysis, Keith Motes
Honors Capstones
No abstract provided.
H2 Temperatures In The Crab Nebula,
2012
Michigan State University
H2 Temperatures In The Crab Nebula, E. D. Loh, J. A. Baldwin, Gary J. Ferland, Z. K. Curtis, C. T. Richardson, A. C. Fabian, P. Salomé
Physics and Astronomy Faculty Publications
We used K-band spectra to measure the H2 excitation temperatures in six molecular knots associated with the filaments in the Crab Nebula. The temperatures are quite high – in the range T∼ 2000–3000 K, just below the H2 dissociation temperature. This is the temperature range over which the H2 1–0 S(1) line at λ2.121 μm has its maximum emissivity per unit mass, so there may be many additional H2 cores with lower temperatures that are too faint to detect. We also measured the electron density in adjacent ionized gas, which on the assumption of …
Near Infrared Hydrogen Emission Line Ratios As Diagnostics Of The Broad Emission Line Region,
2012
University of Melbourne, Australia
Near Infrared Hydrogen Emission Line Ratios As Diagnostics Of The Broad Emission Line Region, Andrea J. Ruff, David J. E. Floyd, Kirk T. Korista, Rachel L. Webster, Ryan Lucian Porter, Gary J. Ferland
Physics and Astronomy Faculty Publications
Broad emission line flux ratios are a powerful diagnostic of the physical conditions of the broad-line region gas in Active Galactic Nuclei. With recent advances in infrared spectroscopy, previously unstudied emission lines provide a new means to investigate the physical nature of the BELR gas. The hydrogen emission lines are particularly sensitive to the upper limits of both the radius from the central ionising source and the number density of the gas. Using an existing subset of near-infrared quasar spectra from the Glikman et al. (2006) sample [1] together with Cloudy photoionization simulations, we confirm the Locally Optimally emitting Cloud …
Forty-Year Calibrated Record Of Earth-Reflected Radiance From Landsat: A Review,
2012
National Aeronautics and Space Administration, Biospheric Sciences Laboratory
Forty-Year Calibrated Record Of Earth-Reflected Radiance From Landsat: A Review, Brian L. Markham, Dennis L. Helder
United States National Aeronautics and Space Administration: Publications
Sensors on Landsat satellites have been collecting images of the Earth's surface for nearly 40 years. These images have been invaluable for characterizing and detecting changes in the land cover and land use of the world. Although initially conceived as primarily picture generating sensors, even the early sensors were radiometrically calibrated and spectrally characterized prior to launch and incorporated some capabilities to monitor their radiometric calibration once on orbit. Recently, as the focus of studies has shifted to monitoring Earth surface parameters over significant periods of time, serious attention has been focused toward bringing the data from all these sensors …
The Venus "Shell-Over-Star" Hieroglyph And Maya Warfare: An Examination Of The Interpretation Of A Mayan Symbol,
2012
Wayne State University
The Venus "Shell-Over-Star" Hieroglyph And Maya Warfare: An Examination Of The Interpretation Of A Mayan Symbol, Claudia Ann Voit
Wayne State University Theses
For decades, Maya scholars have associated the Mayan ―Shell-Star‖ (also referred to as ―Star-War‖) hieroglyph with Maya warfare. Put forward by scholars such as Floyd Lounsbury and David Kelley, and later advanced by Linda Schele, David Freidel, Ian Graham, Peter Matthews, Anthony Aveni and others, there are now dozens of published articles and chapters relating the hieroglyph to Venus and warfare. Venus is one of the most notable celestial objects outside of the Sun and Moon and was highly visible to the inhabitants of the Maya world. The Dresden Codex (an astronomical almanac) contains important information about the planet Venus, …
Screen-Printing Of Ferrite Magnetic Nanoparticles Produced By Carbon Combustion Synthesis Of Oxides,
2012
The University of Texas Rio Grande Valley
Screen-Printing Of Ferrite Magnetic Nanoparticles Produced By Carbon Combustion Synthesis Of Oxides, Karen S. Martirosyan, Gamage Dannangoda, Eduard Galstyan, Dmitri Litvinov
Physics & Astronomy Faculty Publications
The feasibility of screen-printing process of hard ferrite magnetic nanoparticles produced by carbon combustion synthesis of oxides (CCSO) is investigated. In CCSO, the exothermic oxidation of carbon generates a smolder thermal reaction wave that propagates through the solid reactant mixture converting it to the desired oxides. The complete conversion of hexaferrites occurs using reactant mixtures containing 11 wt. % of carbon. The BaFe12O19 and SrFe12O19 hexaferrites had hard magnetic properties with coercivity of 3 and 4.5 kOe, respectively. It was shown that the synthesized nanoparticles could be used to fabricate permanent magnet structures by consolidating them using screen-printing techniques.
Thermal Effects In The Input Optics Of The Enhanced Laser Interferometer Gravitational-Wave Observatory Interferometers,
2012
The University of Texas Rio Grande Valley
Thermal Effects In The Input Optics Of The Enhanced Laser Interferometer Gravitational-Wave Observatory Interferometers, K. L. Dooley, M. A. Arain, D. Fieldbaum, Volker Quetschke
Physics & Astronomy Faculty Publications
We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The …
The Influence Of Soft Spectral Components On The Structure And Stability Of Warm Absorbers In Active Galactic Nuclei,
2012
IUCAA, India
The Influence Of Soft Spectral Components On The Structure And Stability Of Warm Absorbers In Active Galactic Nuclei, Susmita Chakravorty, Ranjeev Misra, Martin Elvis, Ajit K. Kembhavi, Gary J. Ferland
Physics and Astronomy Faculty Publications
The radiation from the central regions of active galactic nuclei, including that from the accretion disc surrounding the black hole, is likely to peak in the extreme-ultraviolet ∼13–100 eV. However, due to Galactic absorption, we are limited to constrain the physical properties, i.e. the black hole mass and the accretion rate, from what observations we have below ∼10 eV or above ∼100 eV. In this paper, we predict the thermal and ionization states of warm absorbers as a function of the shape of the unobservable continuum. In particular we model an accretion disc at kTin∼ 10 eV and …
Herschel Observations Of Extended Atomic Gas In The Core Of The Perseus Cluster,
2012
Rochester Institute of Technology
Herschel Observations Of Extended Atomic Gas In The Core Of The Perseus Cluster, R. Mittal, J. B. R. Oonk, Gary J. Ferland, A. C. Edge, C. P. O'Dea, S. A. Baum, J. T. Whelan, R. M. Johnstone, F. Combes, P. Salomé, A. C. Fabian, G. R. Tremblay, M. Donahue, Russell H. H.
Physics and Astronomy Faculty Publications
We present Herschel observations of the core of the Perseus cluster of galaxies. Especially intriguing is the network of filaments that surround the brightest cluster galaxy, NGC 1275, previously imaged extensively in Hα and CO. In this work, we report detections of far-infrared (FIR) lines, in particular, [C II] 158, [O I] 63, [N II] 122, [O IB] 145 and [O III] 88 μm, withHerschel. All lines are spatially extended, except [O III], with the [C II] line emission extending up to 25 kpc from the core. [C II] emission is found to be co-spatial with Hα and …
Multiphase Signatures Of Active Galactic Nucleus Feedback In Abell 2597,
2012
European Southern Observatory, Germany
Multiphase Signatures Of Active Galactic Nucleus Feedback In Abell 2597, G. R. Tremblay, C. P. O'Dea, S. A. Baum, T. E. Clarke, C. L. Sarazin, J. N. Bregman, F. Combes, M. Donahue, A. C. Edge, A. C. Fabian, Gary J. Ferland, B. R. Mcnamara, R. Mittal, J. B. R. Oonk, A. C. Quillen, H. R. Russell, J. S. Sanders, P. Salomé, G. M. Voit, R. J. Wilman, M. W. Wise
Physics and Astronomy Faculty Publications
We present new Chandra X-ray observations of the brightest cluster galaxy (BCG) in the cool-core cluster Abell 2597 (z= 0.0821). The data reveal an extensive kpc-scale X-ray cavity network as well as a 15-kpc filament of soft-excess gas exhibiting strong spatial correlation with archival Very Large Array radio data. In addition to several possible scenarios, multiwavelength evidence may suggest that the filament is associated with multiphase (103–107 K) gas that has been entrained and dredged-up by the propagating radio source. Stemming from a full spectral analysis, we also present profiles and 2D spectral maps of …
Table Of Contents,
2012
University of South Carolina
Table Of Contents
Journal of the South Carolina Academy of Science
No abstract provided.
Scas Officers And Council Members 2011 - 2012,
2012
University of South Carolina
Scas Officers And Council Members 2011 - 2012
Journal of the South Carolina Academy of Science
No abstract provided.
