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Astrophysics papers — page 85

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CNO driven winds of hot first stars
During the evolution of first stars, the CNO elements may emerge on their surfaces due to the mixing processes. Consequently, these stars may have winds driven purely by CNO elements. We study the…
Jiri Krticka, Jiri KubatOct 16, 2008
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Deceleration of arbitrarily magnetized GRB ejecta: the complete evolution
(Abridged) We aim to quantitatively understand the dynamical effect and observational signatures of magnetization of the GRB ejecta on the onset of the afterglow. We perform ultrahigh-resolution…
P. Mimica, D. Giannios, M. A. AloyOct 16, 2008
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Prompt GeV Emission from Residual Collisions in GRB Outflows: Evidence from Fermi Observations of GRB 080916c
The gamma-rays from gamma-ray bursts (GRBs) are believed to be produced by internal shocks driven by small timescale, ~1 ms, variation in the GRB outflows, and a pair-production spectral cutoff is…
Zhuo LiOct 16, 2008
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Testing Inflation: A Bootstrap Approach
We note that the essential idea of inflation, that the universe underwent a brief period of accelerated expansion followed by a long period of decelerated expansion, can be encapsulated in a…
Latham Boyle, Paul J. SteinhardtOct 16, 2008
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Galactic and Extragalactic Magnetic Fields
The strength of the total magnetic field in our Milky Way from radio Zeeman and synchrotron measurements is about 6 muG near the Sun and several mG in dense clouds, pulsar wind nebulae, and filaments…
Rainer BeckOct 16, 2008
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Dust Extinction in High-z Galaxies with GRB Afterglow Spectroscopy - The 2175Å Feature at z=2.45
We report the clear detection of the 2175A dust absorption feature in the optical afterglow spectrum of the gamma-ray burst (GRB) GRB070802 at a redshift of z=2.45. This is the highest redshift for a…
Á. Elíasdóttir, J. P. U. Fynbo, J. Hjorth et al.Oct 16, 2008
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Gamma-ray burst afterglows : luminosity clustering at infrared wavelengths?
Clustering in the luminosity of the afterglows of gamma-ray burst has been reported in the optical and X-ray. We investigate the possibility that a clustering in the luminosity of the afterglows of…
B. Gendre, S. Pelisson, M. Boer et al.Oct 16, 2008
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Discovery of a very highly extinguished supernova in a luminous infrared galaxy
We report the discovery of a confirmed supernova (SN) and a supernova-candidate in near-infrared images from the ALTAIR/NIRI adaptive optics system on the Gemini-North Telescope and NICMOS on the…
E. Kankare, S. Mattila, S. Ryder et al.Oct 16, 2008
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Forbush decreases and turbulence levels at CME fronts
We seek to estimate the average level of MHD turbulence near coronal mass ejection (CME) fronts as they propagate from the Sun to the Earth. We examine the cosmic ray data from the GRAPES-3 tracking…
Prasad Subramanian, H. M. Antia, S. R. Dugad et al.Oct 16, 2008
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Influence of Dark Matter on Light Propagation in Solar System
We investigated the influence of dark matter on light propagation in the solar system. We assumed the spherical symmetry of spacetime and derived the approximate solution of the Einstein equation,…
Hideyoshi ArakidaOct 16, 2008
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Spitzer Spectral Mapping of Supernova Remnant Cassiopeia A
We present the global distribution of fine structure infrared line emission in the Cassiopeia A supernova remnant using data from the Spitzer Space Telescope's Infrared Spectrograph. We identify…
J. D. T. Smith, Lawrence Rudnick, Tracey Delaney et al.Oct 16, 2008
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A Universal Central Engine Hypothesis for Short and Long GRBs
It is noted that X-ray tails (XRTs) of short, hard γ-ray bursts (SHBs) are similar to X-ray flashes (XRFs). We suggest a universal central engine hypothesis, as a way of accounting for this…
David Eichler, Dafne Guetta, Hadar ManisOct 16, 2008
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Spectroscopic Constraints on (pseudo-)Scalar Particles from Compact Astrophysical Objects
We propose a new method to search for light (pseudo-)scalar particles in the spectra of compact astrophysical objects such as magnetars, pulsars, and quasars. On accounts of compact astrophysical…
Doron Chelouche, Raul Rabadan, Sergey Pavlov et al.Oct 16, 2008
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Compact groups in theory and practice - II. Comparing the observed and predicted nature of galaxies in compact groups
We examine the properties of galaxies in compact groups identified in a mock galaxy catalogue based upon the Millennium Run simulation. The overall properties of groups identified in projection are…
Crystal M. Brasseur, Alan W. McConnachie, Sara L. Ellison et al.Oct 16, 2008
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Spectral Lags Explained as Scattering from Accelerated Scatterers
A quantitative theory of spectral lags for γ-ray bursts (GRBs) is given. The underlying hypothesis is that GRB subpulses are photons that are scattered into our line of sight by local…
David Eichler, Hadar ManisOct 16, 2008
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First Results from the Lick AGN Monitoring Project: The Mass of the Black Hole in Arp 151
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 13 nearby (z < 0.05)…
Misty C. Bentz, Jonelle L. Walsh, Aaron J. Barth et al.Oct 16, 2008
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Cosmic Analogues of the Stern-Gerlach Experiment and the Detection of Light Bosons
We show that, by studying the arrival times of radio pulses from highly-magnetized pulsars, it may be possible to detect light spin-0 bosons (such as axions and axion-like particles) with a much…
Doron Chelouche, Eduardo I. GuendelmanOct 16, 2008
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Testing Mass Loss in Large Magellanic Cloud Cepheids using Infrared and Optical Observations
It has been claimed that Period-Luminosity relations derived from infrared observations of Large Magellanic Cloud (LMC) Cepheids are less dependent on the metallicity of the Cepheids. In this work,…
Hilding R. Neilson, Chow-Choong Ngeow, Shashi M. Kanbur et al.Oct 16, 2008
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On Flare Driven Global Waves
We recently presented evidence of a strong correlation between the energy in the high-frequency part of the acoustic spectrum of the Sun and the solar X-ray flux Karoff & Kjeldsen (2008). The…
C. KaroffOct 16, 2008
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High-resolution molecular line observations of active galaxies
The study of the content, distribution and kinematics of interstellar gas is a key to understand the origin and maintenance of both starburst and nuclear (AGN) activity in galaxies. The processes…
S. Garcia-Burillo, F. Combes, A. Usero et al.Oct 16, 2008
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Prospects for Studies of Stellar Evolution and Stellar Death in the JWST Era
I review the prospects for studies of the advanced evolutionary stages of low-, intermediate- and high-mass stars by the JWST and concurrent facilities, with particular emphasis on how they may help…
Michael J. BarlowOct 16, 2008
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High variability in Vela X-1: giant flares and off states
We investigate the spectral and temporal behavior of the high mass X-ray binary Vela X-1 during a phase of high activity, with special focus on the observed giant flares and off states. INTEGRAL…
Ingo Kreykenbohm, Joern Wilms, Peter Kretschmar et al.Oct 16, 2008
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Pair-Starved Pulsar Magnetospheres
We propose a simple analytic model for the innermost (within the light cylinder of canonical radius) structure of open-magnetic-field lines of a rotating neutron star (NS) with relativistic outflow…
Alex G. Muslimov, Alice K. HardingOct 16, 2008
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The Elemental Composition of High-Energy Cosmic Rays: Measurements with TRACER
TRACER ('Transition Radiation Array for Cosmic Energetic Radiation') is a balloon borne instrument that has been developed to directly measure the composition and energy spectra of individual…
P. J. BoyleOct 16, 2008
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Revisiting the theoretical DBV (V777 Her) instability strip: the MLT theory of convection
We reexamine the theoretical instability domain of pulsating DB white dwarfs (DBV or V777 Her variables). We performed an extensive g-mode nonadiabatic pulsation analysis of DB evolutionary models…
A. H. Córsico, L. G. Althaus, M. M. Miller Bertolami et al.Oct 16, 2008
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