Search For Gravitational Waves Associated With Gamma-Ray Bursts During Ligo Science Run 6 And Virgo Science Runs 2 And 3,
2012
The University of Texas Rio Grande Valley
Search For Gravitational Waves Associated With Gamma-Ray Bursts During Ligo Science Run 6 And Virgo Science Runs 2 And 3, J. Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya D. Mohanty, Volker Quetschke, Joseph D. Romano
Physics & Astronomy Faculty Publications
We present the results of a search for gravitational waves associated with 154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments in 2009-2010, during the sixth LIGO science run and the second and third Virgo science runs. We perform two distinct searches: a modeled search for coalescences of either two neutron stars or a neutron star and black hole, and a search for generic, unmodeled gravitational-wave bursts. We find no evidence for gravitational-wave counterparts, either with any individual GRB in this sample or with the population as a whole. For all GRBs we place lower bounds on the …
Raman Spectroscopy Of Isotactic Polypropylene-Halloysite Nanocomposites,
2012
The University of Texas Rio Grande Valley
Raman Spectroscopy Of Isotactic Polypropylene-Halloysite Nanocomposites, Elamin E. Ibrahim, Dorina M. Chipara, Ram Thapa, Karen Lozano, Mircea Chipara
Physics & Astronomy Faculty Publications
Raman spectroscopy investigations on nanocomposites obtained by dispersing halloysite within isotactic polypropylene are reported. A detailed analysis of the modifications of the regularity band associated to the polymeric matrix is presented. The Raman lines assigned to the polymeric matrix are broadened and weakened as the loading with halloysite is increased. The analysis of Raman lines indicates that the polymeric matrix becomes less crystalline upon the loading with halloysite and that the nanofiller is experiencing a weak dehydration upon dispersion within the polymeric matrix, probably due to the related thermal processing used to achieve the dispersion of halloysite. © 2012 Elamin …
Two-Component Structure Of The HΒ Broad-Line Region In Quasars. I. Evidence From Spectral Principal Component Analysis,
2012
Chinese Academy of Sciences, China
Two-Component Structure Of The HΒ Broad-Line Region In Quasars. I. Evidence From Spectral Principal Component Analysis, Chen Hu, Jian-Min Wang, Luis C. Ho, Gary J. Ferland, Jack A. Baldwin, Ye Wang
Physics and Astronomy Faculty Publications
We report on a spectral principal component analysis (SPCA) of a sample of 816 quasars, selected to have small Fe II velocity shifts with spectral coverage in the rest wavelength range 3500-5500 Å. The sample is explicitly designed to mitigate spurious effects on SPCA induced by Fe II velocity shifts. We improve the algorithm of SPCA in the literature and introduce a new quantity, the fractional-contribution spectrum, that effectively identifies the emission features encoded in each eigenspectrum. The first eigenspectrum clearly records the power-law continuum and very broad Balmer emission lines. Narrow emission lines dominate the second eigenspectrum. The …
Breaks In Thin And Thick Disks Of Edge-On Galaxies Imaged In The Spitzer Survey Of Stellar Structure In Galaxies (S4g),
2012
University of Oulu
Breaks In Thin And Thick Disks Of Edge-On Galaxies Imaged In The Spitzer Survey Of Stellar Structure In Galaxies (S4g), Sébastien Comerón, Trisha Mizusawa
Aerospace, Physics, and Space Science Faculty Publications
Breaks in the radial luminosity profiles of galaxies have until now been mostly studied averaged over disks. Here, we study separately breaks in thin and thick disks in 70 edge-on galaxies using imaging from the Spitzer Survey of Stellar Structure in Galaxies. We built luminosity profiles of the thin and thick disks parallel to midplanes and we found that thin disks often truncate (77%). Thick disks truncate less often (31%), but when they do, their break radius is comparable with that in the thin disk. This suggests either two different truncation mechanisms—one of dynamical origin affecting both disks simultaneously and …
Photocatalytic Activity Of Core/Shell Semiconductor Nanocrystals Featuring Spatial Separation Of Charges,
2012
Bowling Green State University
Photocatalytic Activity Of Core/Shell Semiconductor Nanocrystals Featuring Spatial Separation Of Charges, Dimuthu Perera, Ryan Lorek, Rony S. Khnayzer, Pavel Moroz, Timothy O’Connor, Dmitry Khon, Geoffrey Diederich, Erich Kinder, Scott Lambright, Felix N. Castellano, Mikhail Zamkov
Physics and Astronomy Faculty Publications
The present study investigates the photocatalytic activity of ZnSe/CdS core/shell semiconductor nanocrystals. These nanoparticles exhibit a spatial separation of photoinduced charges between the core and the shell domains, which makes them potentially viable for photocatalytic applications. Unfortunately, one of the excited charges remains inside the core semiconductor and thus cannot efficiently react with the external environment. Here, we explore this issue by investigating the mechanisms of hole extraction from the ZnSe core to the surface of the CdS shell. In particular, the effect of shell thickness in ZnSe/CdS core/shell nanocrystals on the ability of core-localized charges to perform oxidative reactions …
The Disk-Wind-Jet Connection In The Black Hole H 1743-322,
2012
University of Michigan
The Disk-Wind-Jet Connection In The Black Hole H 1743-322, J. M. Miller, J. Raymond, A. C. Fabian, C. S. Reynolds, A. L. King, T. R. Kallman, E. M. Cackett, M. Van Der Klis, D. T. H. Steeghs
Physics and Astronomy Faculty Research Publications
X-ray disk winds are detected in spectrally soft, disk-dominated phases of stellar-mass black hole outbursts. In contrast, compact, steady, relativistic jets are detected in spectrally hard states that are dominated by non-thermal X-ray emission. Although these distinctive outflows appear to be almost mutually exclusive, it is possible that a disk wind persists in hard states but cannot be detected via X-ray absorption lines owing to very high ionization. Here, we present an analysis of a deep, 60 ks Chandra/HETGS observation of the black hole candidate H 1743-322 in the low/hard state. The spectrum shows no evidence of a disk wind, …
Supernova Resonance-Scattering Line Profiles In The Absence Of A Photosphere,
2012
University of Oklahoma
Supernova Resonance-Scattering Line Profiles In The Absence Of A Photosphere, Brian Friesen, E. Baron, David Branch, Bin Chen, Jerod T. Parrent, R. C. Thomas
Dartmouth Scholarship
In supernova (SN) spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of SNe assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists that suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the SN explosion. To explore this possibility, we present a geometrical approach to SN spectrum formation based on the "Elementary Supernova" model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while …
Trajectories And Distribution Of Interstellar Dust Grains In The Heliosphere,
2012
Harvard-Smithsonian Center for Astrophysics
Trajectories And Distribution Of Interstellar Dust Grains In The Heliosphere, Jonathan D. Slavin, Priscilla C. Frisch, Hans-Reinhard Müller, Jacob Heerikhuisen
Dartmouth Scholarship
The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dust density distributions that result. We include up-to-date grain charging calculations using a realistic UV radiation field and full three-dimensional magnetohydrodynamic fluid + kinetic models for the heliosphere. Models with two different (constant) polarities for the solar wind magnetic field (SWMF) are used, with the grain trajectory calculations done …
Exploring The Effects Of Stellar Rotation And Wind Clearing: Debris Disks Around F Stars,
2012
Florida Institute of Technology
Exploring The Effects Of Stellar Rotation And Wind Clearing: Debris Disks Around F Stars, Trisha F. Mizusawa, Luisa M. Rebull, John R. Stauffer, Geoffrey Bryden, Michael Meyer, Inseok Song
Aerospace, Physics, and Space Science Faculty Publications
We have conducted a study of debris disks around F stars in order to explore correlations between rotation, stellar winds, and circumstellar disks. We obtained new 24 {mu}m photometry from the Multiband Imaging Photometer for Spitzer (MIPS) camera for a sample of 188 relatively nearby F dwarfs with various rotation rates and optical colors, and combined it with archival MIPS data for 66 more F stars, as well as Wide-field Infrared Survey Explorer data for the entire sample, plus 9 more F stars. Based on the objects' K{sub s} - [24] and [3.4] - [22] colors, we identify 22 stars …
Breaks In Thin And Thick Disks Of Edge-On Galaxies Imaged In The Spitzer Survey Of Stellar Structure In Galaxies (S4g).,
2012
University of Oulu
Breaks In Thin And Thick Disks Of Edge-On Galaxies Imaged In The Spitzer Survey Of Stellar Structure In Galaxies (S4g)., Sebastien Comeron, Bruce G. Elmegreen, Heikki Salo, Eija Laurikainen, E. Athanassoula, Albert Bosma, Johan H. Knapen, Dimitri A. Gadotti, Kartik Sheth, Joannah L. Hinz, Michael W. Regan, Armando Gil De Paz, Juan Carlos Munoz-Mateos, Karin Menendez-Delmestre, Mark Seibert, Taehyun Kim, Trisha Mizusawa, Jarkko Laine, Luis C. Ho, Benne W. Holwerda
Faculty and Staff Scholarship
Breaks in the radial luminosity profiles of galaxies have until now been mostly studied averaged over disks. Here, we study separately breaks in thin and thick disks in 70 edge-on galaxies using imaging from the Spitzer Survey of Stellar Structure in Galaxies. We built luminosity profiles of the thin and thick disks parallel to midplanes and we found that thin disks often truncate (77%). Thick disks truncate less often (31%), but when they do, their break radius is comparable with that in the thin disk. This suggests either two different truncation mechanisms—one of dynamical origin affecting both disks simultaneously and …
Rotational And Cyclical Variability In Γ Cassiopeiae. Ii. Fifteen Seasons,
2012
Tennessee State University
Rotational And Cyclical Variability In Γ Cassiopeiae. Ii. Fifteen Seasons, Gregory W. Henry, Myron A. Smith
Information Systems and Engineering Management Research Publications
The B0.5 IVe star γ Cas is of great interest because it is the prototype of a small group of classical Be stars having hard X-ray emission of unknown origin. We discuss results from ongoing B and V observations of the γ Cas star–disk system acquired with an Automated Photometric Telescope during the observing seasons 1997–2011. In an earlier study, Smith, Henry, & Vishniac showed that light variations in γ Cas are dominated by a series of comparatively prominent cycles with amplitudes of 0.02–0.03 mag and lengths of 2–3 months, superimposed on a 1.21 day periodic signal some five times …
Modeling Spiral Galaxy Luminosity Profiles,
2012
Utah State University
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 …
Characterizing Sky Variability For Multi-Messenger Astronomy,
2012
Utah State University
Characterizing Sky Variability For Multi-Messenger Astronomy, Rachel Nydegger, Katie Breivik, Shane L. Larson
Browse All Undergraduate research
Multi-messenger astronomy employs both electromagnetic and gravitational wave detectors to paint a richer picture of celestial objects, providing more depth and in formation. Localizing sources with gravitational wave interferometers on the sky is difficult, with resolution of many square degrees. To have simultaneous electromagnetic observations (localized typically to 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 problematic aspect of this observing paradigm is distinguishing …
Non-Detection Of Previously Reported Transits Of Hd 97658b With Most* Photometry,
2012
University of British Columbia
Non-Detection Of Previously Reported Transits Of Hd 97658b With Most* Photometry, Diana Dragomir, Jaymie M. Matthews, Andrew W. Howard, Victoria Antoci, Gregory W. Henry, David B. Guenther, John A. Johnson, Rainer Kuschnig, Geoffrey W. Marcy, Anthony F. J. Moffat, Jason F. Rowe, Slavek M. Rucinski, Dimitar Sasselov, Werner W. Weiss
Information Systems and Engineering Management Research Publications
The radial velocity-discovered exoplanet HD 97658b was recently announced to transit, with a derived planetary radius of 2.93 ± 0.28 R⊕. As a transiting super-Earth orbiting a bright star, this planet would make an attractive candidate for additional observations, including studies of its atmospheric properties. We present and analyze follow-up photometric observations of the HD 97658 system acquired with the Microvariability and Oscillations of STars space telescope. Our results show no transit with the depth and ephemeris reported in the announcement paper. For the same ephemeris, we rule out transits for a planet with radius larger than 2.09 R⊕, corresponding …
Veritas Observations Of Six Bright, Hard-Spectrum Fermi-Lat Blazars,
2012
Department of Applied Physics and Instrumentation, Cork Institute of Technology, Bishopstown, Cork, Ireland
Veritas Observations Of Six Bright, Hard-Spectrum Fermi-Lat Blazars, P. T. Reynolds, Et Al
Physical Sciences Publications
We report on VERITAS very high energy (VHE; E ≥ 100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey spectroscopic data. No VHE emission is detected during the observations of the six sources described here. Corresponding TeV …
Black Holes In The Conical Ensemble,
2012
Loyola University Chicago
Black Holes In The Conical Ensemble, Robert A. Mcnees Iv, Daniel Grumiller
Physics: Faculty Publications and Other Works
We consider black holes in an “unsuitable box”: a finite cavity coupled to a thermal reservoir at a temperature different than the black hole’s Hawking temperature. These black holes are described by metrics that are continuous but not differentiable due to a conical singularity at the horizon. We include them in the Euclidean path integral sum over configurations, and analyze the effect this has on black hole thermodynamics in the canonical ensemble. Black holes with a small deficit (or surplus) angle may have a smaller internal energy or larger density of states than the nearby smooth black hole, but they …
Self-Consistent Magnetic Stellar Evolution Models Of The Detached, Solar-Type Eclipsing Binary Ef Aquarii,
2012
Dartmouth College
Self-Consistent Magnetic Stellar Evolution Models Of The Detached, Solar-Type Eclipsing Binary Ef Aquarii, Gregory A. Feiden, Brian Chaboyer
Dartmouth Scholarship
We introduce a new one-dimensional stellar evolution code, based on the existing Dartmouth code, that self-consistently accounts for the presence of a globally pervasive magnetic field. The methods involved in perturbing the equations of stellar structure, the equation of state, and the mixing-length theory of convection are presented and discussed. As a first test of the code's viability, stellar evolution models are computed for the components of a solar-type, detached eclipsing binary (DEB) system, EF Aquarii, shown to exhibit large disagreements with stellar models. The addition of the magnetic perturbation corrects the radius and effective temperature discrepancies observed in EF …
Energetic Galaxy-Wide Outflows In High-Redshift Ultraluminous Infrared Galaxies Hosting Agn Activity,
2012
Durham University
Energetic Galaxy-Wide Outflows In High-Redshift Ultraluminous Infrared Galaxies Hosting Agn Activity, C. M. Harrison, D. M. Alexander, A. M. Swinbank, Ian Smail, S. Alaghband-Zadeh, F. E. Bauer, S. C. Chapman, A. Del Moro, R. C. Hickox
Dartmouth Scholarship
We present integral field spectroscopy observations, covering the [O III]4959,5007 emission-line doublet of eight high-redshift (z=1.4-3.4) ultra-luminous infrared galaxies (ULIRGs) that host Active Galactic Nuclei (AGN) activity, including known sub-millimetre luminous galaxies (SMGs). The targets have moderate radio luminosities that are typical of high-redshift ULIRGs (L(1.4GHz)=10^(24)-10^(25)W/Hz) and therefore are not radio-loud AGN. We de-couple kinematic components due to the galaxy dynamics and mergers from those due to outflows. We find evidence in the four most luminous systems (L([O III])>~10^(43)erg/s) for the signatures of large-scale energetic outflows: extremely broad [O III] emission (FWHM ~ 700-1400km/s) across ~4-15kpc, with high velocity …
Periodic Structure In The Megaparsec-Scale Jet Of Pks 0637-752,
2012
Curtin University
Periodic Structure In The Megaparsec-Scale Jet Of Pks 0637-752, L. E.H. Godfrey, E. S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present 18 GHz Australia Telescope Compact Array imaging of the megaparsec-scale quasar jet PKS 0637–752 with angular resolution ~0farcs58. We draw attention to a spectacular train of quasi-periodic knots along the inner 11'' of the jet, with average separation ~1.1 arcsec (7.6 kpc projected). We consider two classes of model to explain the periodic knots: those that involve a static pattern through which the jet plasma travels (e.g., stationary shocks) and those that involve modulation of the jet engine. Interpreting the knots as re-confinement shocks implies the jet kinetic power Q jet ~ 1046 erg s–1, but the constant …
An Imaging Neutron/Gamma-Ray Spectrometer,
2012
University of New Hampshire
An Imaging Neutron/Gamma-Ray Spectrometer, James M. Ryan, Chris Bancroft, Peter F. Bloser, Dominique Fourguette, Liane Larocque, Jason S. Legere, Amanda C. Madden, Mark L. Mcconnell, Jane Pavlich, Greg Ritter, Greg Wassick, Marissa Rouseau
Space Science Center
We present the design and development of a dual-species, neutron/γ-ray imaging spectrometer for the identification and location of radioactive and special nuclear materials (SNM). Real-time detection and identification is important for locating fissile materials. These materials, specifically uranium and plutonium, emit neutrons and γ rays via spontaneous or induced fission. Co-located neutron and γ-ray emissions are a sure sign of fissile material, requiring very few spatially correlated events for a significant detection. Our instrument design detects neutrons and γ rays from all sources in its field of view, constructs images of the emission pattern, and reports the spectra for both …
