Black Holes: Myths, Legends And Truths,
2010
Utah State University
Black Holes: Myths, Legends And Truths, Shane L. Larson
Public Talks
No abstract provided.
Stirring Up The Pot: Can Cooling Flows In Galaxy Clusters Be Quenched By Gas Sloshing?,
2010
Harvard-Smithsonian Center for Astrophysics
Stirring Up The Pot: Can Cooling Flows In Galaxy Clusters Be Quenched By Gas Sloshing?, J. A. A. Zuhone, M. Markevitch, R. E. Johnson
Dartmouth Scholarship
X-ray observations of clusters of galaxies reveal the presence of edges in surface brightness and temperature, known as "cold fronts." In relaxed clusters with cool cores, these commonly observed edges have been interpreted as evidence for the "sloshing" of the core gas in the cluster's gravitational potential. Such sloshing may provide a source of heat to the cluster core by mixing hot gas from the cluster outskirts with the cool-core gas. Using high-resolution N-body/Eulerian hydrodynamic simulations, we model gas sloshing in galaxy clusters initiated by mergers with subclusters. The simulations include merger scenarios with gas-filled and gasless subclusters. The …
Comparing The Dark Matter Halos Of Spiral, Low Surface Brightness, And Dwarf Spheroidal Galaxies,
2010
Case Western Reserve University
Comparing The Dark Matter Halos Of Spiral, Low Surface Brightness, And Dwarf Spheroidal Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
We consider dark masses measured from kinematic tracers at discrete radii in galaxies for which baryonic contributions to overall potentials are either subtracted or negligible. Recent work indicates that rotation curves due to dark matter (DM) halos at intermediate radii in spiral galaxies are remarkably similar, with a mean rotation curve given by log10(V c,DM/(km s-1)) = 1.47+0.15-0.19 + 0.5log10(r/kpc). Independent studies show that while estimates of the dark mass of a given dwarf spheroidal (dSph) galaxy are robust only near the half-light radius, data from the Milky Way's (MW's) dSph satellites are consistent with a narrow range of mass …
A Bright Molecular Core In A Crab Nebula Filament,
2010
Michigan State University
A Bright Molecular Core In A Crab Nebula Filament, E. D. Loh, J. A. Baldwin, Gary J. Ferland
Physics and Astronomy Faculty Publications
In a sub-arcsec near-infrared survey of the Crab Nebula using the new Spartan Infrared Camera, we have found several knots with high surface brightness in the H2 2.12 μm line and a very large H2 2.12 μm to Brγ ratio. The brightest of these knots has an intensity ratio I(H2 2.12 μm)/I(Brγ) = 18 ± 9, which we show sets a lower limit on the ratio of masses in the molecular and recombination (i.e., ionized) zones M mol/M rec ≥ 0.9, and a total molecular mass within this single knot M mol ≥ …
Veritas 2008-2009 Monitoring Of The Variable Gamma-Ray Source M 87,
2010
Cork Institute of Technology
Veritas 2008-2009 Monitoring Of The Variable Gamma-Ray Source M 87, P. T. Reynolds, Et. Al.
Physical Sciences Publications
M 87 is a nearby radio galaxy that is detected at energies ranging from radio to very high energy (VHE) gamma rays. Its proximity and its jet, misaligned from our line of sight, enable detailed morphological studies and extensive modeling at radio, optical, and X-ray energies. Flaring activity was observed at all energies, and multi-wavelength correlations would help clarify the origin of the VHE emission. In this paper, we describe a detailed temporal and spectral analysis of the VERITAS VHE gamma-ray observations of M 87 in 2008 and 2009. In the 2008 observing season, VERITAS detected an excess with a …
Testing General Relativity With Current Cosmological Data,
2010
Ewha Womans University
Testing General Relativity With Current Cosmological Data, Scott F. Daniel, Eric V. Linder, Tristan L. Smith, Robert R. Caldwell
Dartmouth Scholarship
Deviations from general relativity, such as could be responsible for the cosmic acceleration, would influence the growth of large-scale structure and the deflection of light by that structure. We clarify the relations between several different model-independent approaches to deviations from general relativity appearing in the literature, devising a translation table. We examine current constraints on such deviations, using weak gravitational lensing data of the CFHTLS and COSMOS surveys, cosmic microwave background radiation data of WMAP5, and supernova distance data of Union2. A Markov chain Monte Carlo likelihood analysis of the parameters over various redshift ranges yields consistency with general relativity …
On Arc-Polarized Structures In The Solar Wind,
2010
Dartmouth College
On Arc-Polarized Structures In The Solar Wind, B U. Sonnerup, S E. Haaland, G Paschmann
Dartmouth Scholarship
A theoretical model is proposed to account for some of the behavior of arc-polarized magnetic structures seen in the solar wind. To this end, an exact analytical solu- tion is developed that describes infinite plane wave trains of arbitrary amplitude in a plasma governed by ideal Hall MHD. The main focus is on intermediate-mode wave trains, which display double-branched magnetic hodogram signatures sim- ilar to those seen in the solar wind. The theoretically derived hodograms have field rotation in the ion-polarized sense at a slightly depressed field magnitude on one branch and an electron-polarized rotation at a slightly enhanced field …
Determining Pulsation Period For An Rr Lyrae Star,
2010
Physics BS
Determining Pulsation Period For An Rr Lyrae Star, Leah M. Fabrizio
Physics
No abstract provided.
A New Technique For Detecting Cosmic Strings In The Cosmos Survey Using Shapelet Decomposition,
2010
California Polytechnic State University, San Luis Obispo
A New Technique For Detecting Cosmic Strings In The Cosmos Survey Using Shapelet Decomposition, Kevin A. James
Physics
The Hubble Space Telescope Treasury Program images collected as part of the Cosmic Evolution Survey were used to develop a new technique for identifying gravitational lensing events resulting from a less-massive cosmic string. By employing Monte Carlo simulations of cosmic strings embedded within the survey, galaxies were decomposed using Hermite Polynomial shapelets, and compared with the unaltered survey. An efficient set of cuts were determined for identifying a cosmic string in shapelet space. The sensitivity of the new methodology was found to be superior at detecting low-mass cosmic strings than previous methods.
Survey Of Meteorite Samples For 92nb, 98tc, And 60fe Using Gamma Ray Spectroscopy,
2010
California Polytechnic State University - San Luis Obispo
Survey Of Meteorite Samples For 92nb, 98tc, And 60fe Using Gamma Ray Spectroscopy, Robert Maxwell
Physics
The focus of this senior project was the use of gamma ray spectroscopy to survey meteorite samples for 92Nb, 98Tc, and 60Fe. The presence of measurable amounts of 26Al (half-life 717,000 years) in meteorites leads astrophysists to believe that 92Nb, 98Tc, and 60Fe should also be present in detectable amounts, though they have not yet been conclusively found. Since the isotopes that were looked for in this senior project are not long lived in comparison to the age of the solar system, their presumed presence indicates that they are continuously being made in outer space and deposited on space objects.
Study Of Accretion Effects Of Transients In Lmxb System,
2010
California Polytechnic State University, San Luis Obispo
Study Of Accretion Effects Of Transients In Lmxb System, Quentin Lamicq
Physics
Neutron stars are intriguing stellar laboratories that are very exciting to study due to the presence of matter in an extreme state. The luminosity of some neutron star transients in low mass X-ray binary (LMXB) systems is known to have quiescent intervals that may be affected by the rate and duration of accretion from the companion star onto the neutron star. We refined a model of the luminosity of the neutron star to allow for possibility that the accretion rate declines at a steady rate until it reaches zero. After a neutron star goes through an outburst, the quiescent period …
Luminosity-Variation Independent Location Of The Circum-Nuclear, Hot Dust In Ngc 4151,
2010
Max-Planck-Institut für Astronomie, Germany
Luminosity-Variation Independent Location Of The Circum-Nuclear, Hot Dust In Ngc 4151, Jorg-Uwe Pott, Matt A. Malkan, Moshe Elitzur, Andrea M. Ghez, Tom M. Herbst, Rainer Schödel, Julien Woillez
Physics and Astronomy Faculty Publications
After recent sensitivity upgrades at the Keck Interferometer (KI), systematic interferometric 2 μm studies of the innermost dust in nearby Seyfert nuclei are within observational reach. Here, we present the analysis of new interferometric data of NGC 4151, discussed in context of the results from recent dust reverberation, spectro-photometric, and interferometric campaigns. The complete data set gives a complex picture, in particular the measured visibilities from now three different nights appear to be rather insensitive to the variation of the nuclear luminosity. KI data alone indicate two scenarios: the K-band emission is either dominated to ~90% by size …
A Bare Molecular Cloud At Z ~ 0.45*,
2010
University of California - Berkeley
A Bare Molecular Cloud At Z ~ 0.45*, Therese M. Jones, Toru Misawa, Jane C. Charlton, Andrew C. Mshar, Gary J. Ferland
Physics and Astronomy Faculty Publications
Several neutral species (Mg I, Si I, Ca I, Fe I) have been detected in a weak Mg II absorption line system (Wr (2796) ~ 0.15 Å) at z ~ 0.45 along the sightline toward HE0001-2340. These observations require extreme physical conditions, as noted in D'Odorico. We place further constraints on the properties of this system by running a wide grid of photoionization models, determining that the absorbing cloud that produces the neutral absorption is extremely dense (~100-1000 cm-3), cold (< 100 K), and has significant molecular content (~72%-94%). Structures of this size and temperature have been detected in Milky Way CO surveys and have been predicted in hydrodynamic simulations of turbulent gas. In order to explain the observed line profiles in all neutral and singly ionized chemical transitions, the lines must suffer from unresolved saturation and/or the absorber must partially cover the broad emission line region of the background quasar. In addition to this highly unusual cloud, three other ordinary weak Mg II clouds (within densities of ~0.005 cm-3 and temperatures of ~10, 000 K) lie within 500 km s-1 along the …
Analysis Of The Blazar 1es1218+30.4,
2010
California Polytechnic State University - San Luis Obispo
Analysis Of The Blazar 1es1218+30.4, Timothy Wolf
Physics
I analyzed the Blazar 1ES1218+30.4 in the high energy spectrum with VERITAS telescope data. The analysis used improved the energy spectrum obtained for the blazar from a maximum of 2.49 TeV to 3.85 TeV. The flux for this point is greater than the previous fit equation predicts, indicating a possible shoulder in the EBL, or Extragalactic Background Light.
Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run,
2010
The University of Texas Rio Grande Valley
Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run, J. Abadie, B. P. Abbott, R. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Malik Rakhmanov, Joseph D. Romano
Physics & Astronomy Faculty Publications
Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [ - 5, + 1)s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U-test, we find no …
Inhomogeneity-Induced Spin Current In Atomic And Condensed Matter Systems,
2010
Brigham Young University - Provo
Inhomogeneity-Induced Spin Current In Atomic And Condensed Matter Systems, Bailey Hsu
Theses and Dissertations
I derive and apply quantum propagator techniques to atomic and condensed matter systems. I observe many interesting features by following the evolution of a wavepacket. In atomic systems, I revisit the Stern-Gerlach effect and study the spin dynamics inside an inhomogeneous magnetic field. The results I obtained are not exactly the same as the textbook description of the effect which is usually a manifestation of a perfect space and spin entanglement. This discovery can provide insight on more reliable quantum computation device designs. In condensed matter systems, the doping concentration inhomogeneity leads to the Rashba spin-orbit interaction. This makes it …
Exotic Smoothness In Four Dimensions And Euclidean Quantum Gravity,
2010
Merrimack
Exotic Smoothness In Four Dimensions And Euclidean Quantum Gravity, Christopher L. Duston
Physics Faculty Publications
In this paper we calculate the effect of the inclusion of exotic smooth structures on typical observables in Euclidean quantum gravity. We do this in the semiclassical regime for several gravitational free-field actions and find that the results are similar, independent of the particular action that is chosen. These are the first results of their kind in dimension four, which we extend to include one-loop contributions as well. We find these topological features can have physically significant results without the need for additional exotic physics.
Dissecting Galaxy Formation. Ii. Comparing Substructure In Pure Dark Matter And Baryonic Models,
2010
Argelander Institute for Astronomy
Dissecting Galaxy Formation. Ii. Comparing Substructure In Pure Dark Matter And Baryonic Models, Emilio Romano-Diaz, Isaac Shlosman, Clayton Heller, Yehuda Hoffman
Physics & Astronomy: Faculty Publications
We compare the substructure evolution in pure dark matter (DM) halos with those in the presence of baryons, hereafter PDM and BDM models, respectively. The prime halos have been analyzed in the previous work. Models have been evolved from identical initial conditions which have been constructed by means of the constrained realization method. The BDM model includes star formation and feedback from stellar evolution onto the gas. A comprehensive catalog of subhalo populations has been compiled and individual and statistical properties of subhalos analyzed, including their orbital differences. We find that subhalo population mass functions in PDM and BDM are …
Visitors From The Halo: 11 Gyr Old White Dwarfs In The Solar Neighborhood,
2010
Smithsonian Astrophysical Observatory
Visitors From The Halo: 11 Gyr Old White Dwarfs In The Solar Neighborhood, Mukremin Kilic, Ted Von Hippel, Et Al.
Publications
We report the discovery of three nearby old halo white dwarf (WD) candidates in the Sloan Digital Sky Survey (SDSS), including two stars in a common proper motion binary system. These candidates are selected from our 2800deg2 proper motion survey on the Bok and U.S. Naval Observatory Flagstaff Station 1.3 m telescopes, and they display proper motions of 0˝.4-0˝.5 yr¯1. Follow-up MMT spectroscopy and near-infrared photometry demonstrate that all three objects are hydrogen-dominated atmosphere WDs with T eff ≈ 3700-4100 K. For average mass WDs, these temperature estimates correspond to cooling ages of 9-10 Gyr, distances of 70-80 pc, and …
Retired A Stars And Their Companions. Iv. Seven Jovian Exoplanets From Keck Observatory,
2010
California Institute of Technology
Retired A Stars And Their Companions. Iv. Seven Jovian Exoplanets From Keck Observatory, John Asher Johnson, Andrew W. Howard, Brendan P. Bowler, Gregory W. Henry, Geoffrey W. Marcy, Jason T. Wright, Debra A. Fischer, Howard Isaacson
Information Systems and Engineering Management Research Publications
We report precise Doppler measurements of seven subgiants from Keck Observatory. All seven stars show variability in their radial velocities consistent with planet-mass companions in Keplerian orbits. The host stars have masses ranging from 1.1 ≤ M⋆/M⊙ ≤ 1.9, radii 3.4 ≤ R⋆/R⊙ ≤ 6.1, and metallicities -0.21 ≤ [Fe/H] ≤ +0.26. The planets are all more massive than Jupiter (MP sin i > 1 MJup) and have semimajor axes a > 1 AU. We present millimagnitude photometry from the T3 0.4 m APT at Fairborn Observatory for five of the targets. Our monitoring shows these stars to be photometrically stable, further …
