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 …
Development And Test Of A Vlf-Receiver For Monitoring Solar Flares,
2012
University of Alabama in Huntsville
Development And Test Of A Vlf-Receiver For Monitoring Solar Flares, Liz Klar, Chris Phillips, Akito D. Kawamura, Eric Zirnstein
Von Braun Symposium Student Posters
No abstract provided.
Long-Lived Electron Spins In A Modulation Doped (100) Gaas Quantum Well,
2012
Brigham Young University
Long-Lived Electron Spins In A Modulation Doped (100) Gaas Quantum Well, John S. Colton, D. Meyer, K Clark, D. Craft, J. Cutler, T. Park, P. White
Faculty Publications
We have measured T1 spin lifetimes of a 14 nm modulation-doped (100) GaAs quantum well using a time-resolved pump-probe Kerr rotation technique. The quantum well was selected by tuning the wavelength of the probe laser. T1 lifetimes in excess of 1 Us were measured at 1.5 K and 5.5 T, exceeding the typical T2 lifetimes that have been measured in GaAs and II-VI quantum wells by orders of magnitude. We observed effects from nuclear polarization, which were largely removable by simultaneous nuclear magnetic resonance, along with two distinct lifetimes under some conditions that likely result from probing two differently localized …
A Method For Localizing Energy Dissipation In Blazars Using Fermi Variability,
2012
University of Maryland - Baltimore County
A Method For Localizing Energy Dissipation In Blazars Using Fermi Variability, Amanda Dotson, Markos Georganopoulos, Demosthenes Kazanas, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
The distance of a Fermi-detected blazar γ-ray emission site from a supermassive black hole is a matter of active debate. Here we present a method for testing if the GeV emission of powerful blazars is produced within the subparsec-scale broad-line region (BLR) or farther out in the parsec-scale molecular torus (MT) environment If the GeV emission takes place within the BLR, the inverse Compton (IC) scattering of the BLR ultraviolet (UV) seed photons that produces the γ-rays takes place at the onset of the Klein–Nishina regime. This causes the electron cooling time to become practically energy-independent and the variation of …
Collisionless Reconnection: Magnetic Field Line Interaction,
2012
Dartmouth College
Collisionless Reconnection: Magnetic Field Line Interaction, R A. Treumann, W Baumjohann, W. D. Gonzalez
Dartmouth Scholarship
Magneticfieldlinesarequantumobjectscarrying onequantum0=2πh ̄/eofmagneticfluxandhavefinite radius λm. Here we argue that they possess a very specific dynamicalinteraction.Parallelfieldlinesrejecteachother. When confined to a certain area they form two-dimensional lattices of hexagonal structure. We estimate the filling factor of such an area. Anti-parallel field lines, on the other hand, at- tract each other. We identify the physical mechanism as being due to the action of the gauge potential field, which we de- termine quantum mechanically for two parallel and two anti- parallel field lines. The distortion of the quantum electrody- namic vacuum causes a cloud of virtual pairs. We calculate the virtual pair production rate …
Cyclic Universe With An Inflationary Phase From A Cosmological Model With Real Gas Quintessence,
2012
Technological University Dublin
Cyclic Universe With An Inflationary Phase From A Cosmological Model With Real Gas Quintessence, Rossen Ivanov, Emil Prodanov
Articles
Phase-plane stability analysis of a dynamical system describing the Universe as a two-fraction uid containing baryonic dust and real virial gas quintessence is presented. Existence of a stable periodic solution experiencing in ationary periods is shown. A van der Waals quintessence model is revisited and cyclic Universe solution again found.
Phys 260,
2012
University of Nebraska - Lincoln
Radiation From Accelerated Particles In Relativistic Jets With Shocks, Shear-Flow, And Reconnection,
2012
University of Alabama in Huntsville
Radiation From Accelerated Particles In Relativistic Jets With Shocks, Shear-Flow, And Reconnection, K.-I. Nishikawa, P. Hardee, Y. Mizuno, I. Dutan, B. Zhang, M. Medvedev, E. J. Chor, K. W. Min, J. Niemiec, Y Mizuno, A Nordlund, J T. Frederiksen, H Sol, M Pohl, Dieter H. Hartmann
Publications
We have investigated particle acceleration and shock structure associated with an unmagnetized rel-ativistic jet propagating into an unmagnetized plasma for electron-positron and electron-ion plasmas. Strong magnetic fields generated in the trailing jet shock lead to transverse deflection and acceleration of the electrons. We have self-consistently calculated the radiation from the electrons accelerated in the turbulent magnetic fields for different jet Lorentz factors. We find that the synthetic spectra depend on the bulk Lorentz factor of the jet, the jet temperature, and the strength of the magnetic fields generated in the shock. We have investigated the generation of magnetic fields associated …
Constraints On Cosmic Rays, Magnetic Fields, And Dark Matter From Gamma-Ray Observations Of The Coma Cluster Of Galaxies With Veritas And Fermi,
2012
Cork Institute of Technology
Constraints On Cosmic Rays, Magnetic Fields, And Dark Matter From Gamma-Ray Observations Of The Coma Cluster Of Galaxies With Veritas And Fermi, P. T. Reynolds, Et. Al.
Physical Sciences Publications
Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E > 100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order …
Self-Consistent Model Of The Interstellar Pickup Protons, Alfvenic Turbulence, And Core Solar Wind In The Outer Heliosphere,
2012
Florida Institute of Technology
Self-Consistent Model Of The Interstellar Pickup Protons, Alfvenic Turbulence, And Core Solar Wind In The Outer Heliosphere, Konstantin V. Gamayunov, Ming Zhang, Nikolai V. Pogorelov, Jacob Heerikhuisen, Hamid K. Rassoul
Aerospace, Physics, and Space Science Faculty Publications
A self-consistent model of the interstellar pickup protons, the slab component of the Alfvenic turbulence, and core solar wind (SW) protons is presented for r {>=} 1 along with the initial results of and comparison with the Voyager 2 (V2) observations. Two kinetic equations are used for the pickup proton distribution and Alfvenic power spectral density, and a third equation governs SW temperature including source due to the Alfven wave energy dissipation. A fraction of the pickup proton free energy, f{sub D} , which is actually released in the waveform during isotropization, is taken from the quasi-linear consideration without …
Self-Consistent Model Of The Interstellar Pickup Protons, Alfvenic Turbulence, And Core Solar Wind In The Outer Heliosphere,
2012
Florida Institute of Technology
Self-Consistent Model Of The Interstellar Pickup Protons, Alfvenic Turbulence, And Core Solar Wind In The Outer Heliosphere, Konstantin V. Gamayunov, Ming Zhang, Hamid K. Rassoul, Nikolai V. Pogorelov, Jacob Heerikhuisen
Aerospace, Physics, and Space Science Faculty Publications
A self-consistent model of the interstellar pickup protons, the slab component of the Alfvenic turbulence, and core solar wind (SW) protons is presented for r {>=} 1 along with the initial results of and comparison with the Voyager 2 (V2) observations. Two kinetic equations are used for the pickup proton distribution and Alfvenic power spectral density, and a third equation governs SW temperature including source due to the Alfven wave energy dissipation. A fraction of the pickup proton free energy, f{sub D} , which is actually released in the waveform during isotropization, is taken from the quasi-linear consideration without …
Four Highly Dispersed Millisecond Pulsars Discovered In The Arecibo Palfa Galactic Plane Survey,
2012
The University of Texas Rio Grande Valley
Four Highly Dispersed Millisecond Pulsars Discovered In The Arecibo Palfa Galactic Plane Survey, F. Crawford, Kevin Stovall, A. G. Lyne, B. W. Stappers, D. J. Nice, I. Stairs, P. Lazarus, J. W.T. Hessels, P. Freire, Fredrick Jenet
Physics & Astronomy Faculty Publications
We present the discovery and phase-coherent timing of four highly dispersed millisecond pulsars (MSPs) from the Arecibo PALFA Galactic plane survey: PSRs J1844+0115, J1850+0124, J1900+0308, and J1944+2236. Three of the four pulsars are in binary systems with low-mass companions, which are most likely white dwarfs, and which have orbital periods on the order of days. The fourth pulsar is isolated. All four pulsars have large dispersion measures (DM >100 pccm-3), are distant (≳ 3.4kpc), faint at 1.4GHz (≲ 0.2mJy), and are fully recycled (with spin periods P between 3.5 and 4.9ms). The three binaries also have very small orbital eccentricities, …
Two Millisecond Pulsars Discovered By The Palfa Survey And A Shapiro Delay Measurement,
2012
The University of Texas Rio Grande Valley
Two Millisecond Pulsars Discovered By The Palfa Survey And A Shapiro Delay Measurement, J. S. Deneva, P. C.C. Freire, J. M. Cordes, A. G. Lyne, S. M. Ransom, I. Cognard, F. Camilo, D. J. Nice, Fredrick A. Jenet, Kevin Stovall
Physics & Astronomy Faculty Publications
We present two millisecond pulsar discoveries from the PALFA survey of the Galactic plane with the Arecibo telescope. PSR J1955+2527 is an isolated pulsar with a period of 4.87ms, and PSR J1949+3106 has a period of 13.14ms and is in a 1.9day binary system with a massive companion. Their timing solutions, based on 4years of timing measurements with the Arecibo, Green Bank, Nançay, and Jodrell Bank telescopes, allow precise determination of spin and astrometric parameters, including precise determinations of their proper motions. For PSR J1949+3106, we can clearly detect the Shapiro delay. From this we measure the pulsar mass to …
Contribution Of The Accretion Disk, Hot Corona, And Obscuring Torus To The Luminosity Of Seyfert Galaxies: Integral And Spitzer Observations,
2012
Russian Academy of Sciences
Contribution Of The Accretion Disk, Hot Corona, And Obscuring Torus To The Luminosity Of Seyfert Galaxies: Integral And Spitzer Observations, S. Sazonov, S. P. Willner, A. D. Goulding, R. C. Hickox
Dartmouth Scholarship
We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spitzer mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei (AGNs) from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal-to-noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L 15 μm∝L0.74 ± 0.06 HX. Assuming that the observed MIR emission is radiation …
