Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- University of Kentucky (10)
- Brigham Young University (5)
- University of Texas Rio Grande Valley (5)
- San Jose State University (4)
- Dartmouth College (3)
-
- Old Dominion University (3)
- University of Missouri, St. Louis (2)
- University of Tennessee, Knoxville (2)
- Valparaiso University (2)
- Western University (2)
- Bowling Green State University (1)
- Embry-Riddle Aeronautical University (1)
- Georgia Southern University (1)
- Kennesaw State University (1)
- Merrimack College (1)
- Utah State University (1)
- Wilfrid Laurier University (1)
- Keyword
-
- Circumstellar matter (3)
- Be (2)
- CD (2)
- Clusters (2)
- Elliptical and lenticular (2)
-
- Galaxies (2)
- Galaxies: Seyfert (2)
- Intracluster medium (2)
- Outflows (2)
- Publications (2)
- Quantum (2)
- Quantum physics (2)
- Stars: variables: general (2)
- Stars: winds (2)
- Structure maps (2)
- Accretion (1)
- Accretion disks (1)
- Amplitudes (1)
- Analytical solution (1)
- Astronomy (1)
- Black hole mass (1)
- Black hole physics (1)
- Boost-invariance (1)
- CLUSTER satellite (1)
- Carbon nanotubes (1)
- Carter Constant (1)
- Champ magnétique (1)
- Charge balance function (1)
- Circular Orbits (1)
- Cluster expansions (1)
- Publication
-
- Physics and Astronomy Faculty Publications (12)
- Faculty Publications (9)
- Physics and Astronomy Faculty Publications and Presentations (5)
- Physics Faculty Publications (4)
- Dartmouth Scholarship (3)
-
- Cross Sections (2)
- Physics Faculty Works (2)
- Physics and Astronomy Publications (2)
- All Physics Faculty Publications (1)
- Department of Physics and Astronomy Faculty Publications (1)
- Faculty and Research Publications (1)
- Physics and Astronomy Faculty Presentations (1)
- Physics and Computer Science Faculty Publications (1)
- Publications (1)
Articles 1 - 30 of 45
Full-Text Articles in Physics
Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis
Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis
Faculty and Research Publications
I present results for top quark production in hadronic collisions at LHC and Tevatron energies. The soft-gluon corrections to the differential cross section are resummed at next-to-next-to-leading-logarithm accuracy via the two-loop soft anomalous dimension matrices. Approximate next-to-next-to-leading-order differential and total cross sections are calculated. Detailed theoretical predictions are shown for the t (t) over bar cross section and the top quark p(T) distribution at the Tevatron and the LHC.
D-Dimensional Bose Gases And The Lambert W Function, Sree Ram Valluri, J Tanguay, M Gil, D J. Jeffrey
D-Dimensional Bose Gases And The Lambert W Function, Sree Ram Valluri, J Tanguay, M Gil, D J. Jeffrey
Physics and Astronomy Publications
The applications of the Lambert W function (also known as the W function) to D-dimensional Bose gases are presented. We introduce two sets of families of logarithmic transcendental equations that occur frequently in thermodynamics and statistical mechanics and present their solution in terms of the W function. The low temperature T behavior of free ideal Bose gases is considered in three and four dimensions. It is shown that near condensation in four dimensions, the chemical potential μ and pressure P can be expressed in terms of T through the W function. The low T behavior of one- and two-dimensional ideal …
Source Attribution Of Ozone In Southeast Texas Before And After The Deepwater Horizon Accident Using Satellite, Sonde, Surface Monitor, And Air Mass Trajectory Data, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Marc Taylor, Mark R. Schoeberl
Source Attribution Of Ozone In Southeast Texas Before And After The Deepwater Horizon Accident Using Satellite, Sonde, Surface Monitor, And Air Mass Trajectory Data, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Marc Taylor, Mark R. Schoeberl
Physics and Astronomy Faculty Presentations
Since the summer of 2004, over 300 ozonesondes have been launched from Rice University (29.7 N, 95.4 W) or the University of Houston (29.7 N, 95.3 W), each < 5 km from downtown Houston. The Texas Commission on Environmental Quality maintains a large database of hourly surface ozone observations in Southeast Texas. In this study, we identify the contributions to surface ozone pollution levels from natural and anthropogenic sources, both local and remote in nature. This source identification is performed two ways: 1) through an analysis of sonde data, including ozone concentrations, wind speed and direction, and relative humidity data, and 2) through an analysis that combines trajectory calculations with surface monitor data. We also examine regional changes in Ozone Monitoring Instrument (OMI) measurements of formaldehyde and ozone from 2004 – 2010. In particular, we compare the 2010 sonde, surface monitor, and satellite data after the Deepwater Horizon accident with data from previous years to determine the impact, if any, of the large source of hydrocarbons in the Gulf of Mexico on air quality in Southeast Texas.
The Carter Constant For Inclined Orbits About A Massive Kerr Black Hole: I. Circular Orbits, Peter G. Komorowski, Sree Ram Valluri, Martin Houde
The Carter Constant For Inclined Orbits About A Massive Kerr Black Hole: I. Circular Orbits, Peter G. Komorowski, Sree Ram Valluri, Martin Houde
Physics and Astronomy Publications
In an extreme binary black hole system, an orbit will increase its angle of inclination (ι) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar orbits, and develop an analysis that is independent of and complements radiation-reactionmodels. For a Schwarzschild black hole, the polar orbits represent the abutment between the prograde and retrograde orbits at whichQis at its maximum value for given values of the latus rectum (˜l ) and the eccentricity (e). The introduction of spin (S˜ = |J|/M2) to themassive black hole causes this boundary, or abutment, …
Structure And Feedback In 30 Doradus. I. Observations, E. W. Pellegrini, J. A. Baldwin, Gary J. Ferland
Structure And Feedback In 30 Doradus. I. Observations, E. W. Pellegrini, J. A. Baldwin, Gary J. Ferland
Physics and Astronomy Faculty Publications
We have completed a new optical imaging and spectrophotometric survey of a 140 × 80 pc2 region of 30 Doradus centered on R136, covering key optical diagnostic emission lines including Hα, Hβ, Hγ, [O III] λλ4363, 4959, 5007, [N II] λλ6548, 6584, [SII] λλ6717, 6731 [S III] λ6312, and in some locations [S III] λ9069. We present maps of fluxes and intensity ratios for these lines, and catalogs of isolated ionizing stars, elephant-trunk pillars, and edge-on ionization fronts. The final science-quality spectroscopic data products are available to the public. Our analysis of the new data finds that, while stellar …
Tuning The Morphology Of Au/Cds Nanocomposites Through Temperature-Controlled Reduction Of Gold-Oleate Complexes, Elena Khon, Nishshanka N. Hewa-Kasakarage, Ian Nemitz, Krishna Acharya, Mikhail Zamkov
Tuning The Morphology Of Au/Cds Nanocomposites Through Temperature-Controlled Reduction Of Gold-Oleate Complexes, Elena Khon, Nishshanka N. Hewa-Kasakarage, Ian Nemitz, Krishna Acharya, Mikhail Zamkov
Physics and Astronomy Faculty Publications
A general synthetic strategy for controlling the shape of gold domains grown onto CdS semiconductor nanocrystals is presented. The colloidal growth of Au nanoparticles is based on the temperature-controlled reduction of Au-oleate complexes on the surface of CdS and allows for precise tuning of nanoparticle diameters from 2.5 to 16 nm simply by adjusting the temperature of the growth solution, whereas the shape of Au/CdS nanocomposites can be controllably switched between matchsticks and barbells via the reaction rate. Depending on the exact morphology of Au and CdS domains, fabricated nanocomposites can undergo evaporation-induced self-assembly on a substrate either through end-to-end …
Ultra-Compact Dwarfs In The Core Of The Coma Cluster, Juan P. Madrid, Alister W. Graham, William E. Harris, Paul Goudfrooij, Duncan A. Forbes, David Carter, John P. Blakeslee, Lee R. Spitler, Henry C. Ferguson
Ultra-Compact Dwarfs In The Core Of The Coma Cluster, Juan P. Madrid, Alister W. Graham, William E. Harris, Paul Goudfrooij, Duncan A. Forbes, David Carter, John P. Blakeslee, Lee R. Spitler, Henry C. Ferguson
Physics and Astronomy Faculty Publications and Presentations
We have discovered both a red and a blue subpopulation of ultra-compact dwarf (UCD) galaxy candidates in the Coma galaxy cluster. We analyzed deep F475W (Sloan g) and F814W (I) Hubble Space Telescope images obtained with the Advanced Camera for Surveys Wide Field Channel as part of the Coma Cluster Treasury Survey and have fitted the light profiles of similar to 5000 point-like sources in the vicinity of NGC 4874, one of the two central dominant galaxies of the Coma Cluster. Although almost all of these sources are globular clusters that remain unresolved, we found that 52 objects have effective …
Cross Sections Fall 2010, Department Of Physics And Astronomy
Cross Sections Fall 2010, Department Of Physics And Astronomy
Cross Sections
No abstract provided.
New Tests Of General Relativity, Quentin Bailey
New Tests Of General Relativity, Quentin Bailey
Publications
The last decade has seen a rapid increase in the number of precision tests of relativity. This research has been motivated by the intriguing possibility that tiny deviations from relativity might arise in the underlying theory that is widely believed to successfully mesh General Relativity (GR) with quantum physics. Many of these tests have been analyzed within an effective field theory framework which generically describes possible deviations from exact relativity and contains some traditional test frameworks as limiting cases. One part of the activity has been a resurgence of interest in tests of relativity in the Minkowski-spacetime context, where Lorentz …
The Trilinear Hamiltonian: A Zero-Dimensional Model Of Hawking Radiation From A Quantized Source, Paul D. Nation, Miles P. Blencowe
The Trilinear Hamiltonian: A Zero-Dimensional Model Of Hawking Radiation From A Quantized Source, Paul D. Nation, Miles P. Blencowe
Dartmouth Scholarship
We investigate a quantum parametric amplifier with dynamical pump mode, viewed as a zero-dimensional model of Hawking radiation from an evaporating black hole. We derive the conditions under which the spectrum of particles generated from vacuum fluctuations deviates from the thermal spectrum predicted for the conventional parametric amplifier. We find that significant deviations arise when the pump mode (black hole) has emitted nearly half of its initial energy into the signal (Hawking radiation) and idler (in-falling particle) modes. As a model of black hole dynamics, this finding lends support to the view that late-time Hawking radiation contains information about the …
On The Disappearance Of The Broad-Line Region In Low-Luminosity Active Galactic Nuclei, Moshe Elitzur, Luis C. Ho
On The Disappearance Of The Broad-Line Region In Low-Luminosity Active Galactic Nuclei, Moshe Elitzur, Luis C. Ho
Physics and Astronomy Faculty Publications
The disk-wind scenario for the broad-line region (BLR) and toroidal obscuration in active galactic nuclei (AGNs) predicts the disappearance of the BLR at low luminosities. In accordance with the model predictions, data from a nearly complete sample of nearby AGNs show that the BLR disappears at luminosities lower than 5 × 1039(M/107 M⊙)2/3 erg s-1, where M is the black hole mass. The radiative efficiency of accretion onto the black hole is ≲10-3 for these sources, indicating that their accretion is advection-dominated.
Long-Lived Time-Dependent Remnants During Cosmological Symmetry Breaking: From Inflation To The Electroweak Scale, Marcelo Gleiser, Noah Graham, Nikitas Stamatopoulos
Long-Lived Time-Dependent Remnants During Cosmological Symmetry Breaking: From Inflation To The Electroweak Scale, Marcelo Gleiser, Noah Graham, Nikitas Stamatopoulos
Dartmouth Scholarship
Through a detailed numerical investigation in three spatial dimensions, we demonstrate that long-lived time-dependent field configurations emerge dynamically during symmetry breaking in an expanding de Sitter spacetime. We investigate two situations: a single scalar field with a double-well potential and an SU(2) non-Abelian Higgs model. For the single scalar, we show that large-amplitude oscillon configurations emerge spontaneously and persist to contribute about 1.2% of the energy density of the Universe. We also show that for a range of parameters, oscillon lifetimes are enhanced by the expansion and that this effect is a result of parametric resonance. For the SU(2) case, …
Mutation Size Optimizes Speciation In An Evolutionary Model, Nathan Dees, Sonya Bahar
Mutation Size Optimizes Speciation In An Evolutionary Model, Nathan Dees, Sonya Bahar
Physics Faculty Works
The role of mutation rate in optimizing key features of evolutionary dynamics has recently been investigated in various computational models. Here, we address the related question of how maximum mutation size affects the formation of species in a simple computational evolutionary model. We find that the number of species is maximized for intermediate values of a mutation size parameter μ; the result is observed for evolving organisms on a randomly changing landscape as well as in a version of the model where negative feedback exists between the local population size and the fitness provided by the landscape. The same result …
Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller
Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller
Department of Physics and Astronomy Faculty Publications
We conduct numerical experiments by evolving gaseous/stellar disks embedded in live dark matter halos aiming at quantifying the effect of gas spatial resolution and gas content on the bar evolution. Three model sequences have been constructed using different resolutions, and the gas fraction has been varied along each sequence within the range of f g = 0%-50%, but keeping the disk and halo properties unchanged. We find that the spatial resolution becomes important with an increase in the gas content. For the higher resolution model sequences, we observe a bimodal behavior in the bar evolution with respect to the gas …
Herschel Photometry Of Brightest Cluster Galaxies In Cooling Flow Clusters, A. C. Edge, J. B. R. Oonk, R. Mittal, S. W. Allen, S. A. Baum, H. Böhringer, J. N. Bregman, M. N. Bremer, F. Combes, C. S. Crawford, M. Donahue, E. Egami, A. C. Fabian, Gary J. Ferland, S. L. Hamer, N. A. Hatch, W. Jaffe, R. M. Johnstone, B. R. Mcnamara, C. P. O'Dea, P. Popesso, A. C. Quillen, P. Salomé, C. L. Sarazin, G. M. Voit, R. J. Wilman, M. W. Wise
Herschel Photometry Of Brightest Cluster Galaxies In Cooling Flow Clusters, A. C. Edge, J. B. R. Oonk, R. Mittal, S. W. Allen, S. A. Baum, H. Böhringer, J. N. Bregman, M. N. Bremer, F. Combes, C. S. Crawford, M. Donahue, E. Egami, A. C. Fabian, Gary J. Ferland, S. L. Hamer, N. A. Hatch, W. Jaffe, R. M. Johnstone, B. R. Mcnamara, C. P. O'Dea, P. Popesso, A. C. Quillen, P. Salomé, C. L. Sarazin, G. M. Voit, R. J. Wilman, M. W. Wise
Physics and Astronomy Faculty Publications
The dust destruction timescales in the cores of clusters of galaxies are relatively short given their high central gas densities. However, substantial mid-infrared and sub-mm emission has been detected in many brightest cluster galaxies. In this letter we present Herschel PACS and SPIRE photometry of the brightest cluster galaxy in three strong cooling flow clusters, A1068, A2597 and Zw3146. This photometry indicates that a substantial mass of cold dust is present (> 3×107 M⊙) at temperatures significantly lower (20–28 K) than previously thought based on limited MIR and/or sub-mm results. The mass and temperature of the dust appear …
A Sea Change In Eta Carinae, Andrea Mehner, Kris Davidson, Roberta M. Humphreys, John C. Martin, Kazunori Ishibashi, Gary J. Ferland, Nolan R. Walborn
A Sea Change In Eta Carinae, Andrea Mehner, Kris Davidson, Roberta M. Humphreys, John C. Martin, Kazunori Ishibashi, Gary J. Ferland, Nolan R. Walborn
Physics and Astronomy Faculty Publications
Major stellar-wind emission features in the spectrum of η Car have recently decreased by factors of order 2 relative to the continuum. This is unprecedented in the modern observational record. The simplest, but unproven, explanation is a rapid decrease in the wind density.
Herschel Observations Of Fir Emission Lines In Brightest Cluster Galaxies, A. C. Edge, J. B. R. Oonk, R. Mittal, S. W. Allen, S. A. Baum, H. Böhringer, J. N. Bregman, M. N. Bremer, F. Combes, C. S. Crawford, M. Donahue, E. Egami, A. C. Fabian, Gary J. Ferland, S. L. Hamer, N. A. Hatch, W. Jaffe, R. M. Johnstone, B. R. Mcnamara, C. P. O'Dea, P. Popesso, A. C. Quillen, P. Salomé, C. L. Sarazin, G. M. Voit, R. J. Wilman, M. W. Wise
Herschel Observations Of Fir Emission Lines In Brightest Cluster Galaxies, A. C. Edge, J. B. R. Oonk, R. Mittal, S. W. Allen, S. A. Baum, H. Böhringer, J. N. Bregman, M. N. Bremer, F. Combes, C. S. Crawford, M. Donahue, E. Egami, A. C. Fabian, Gary J. Ferland, S. L. Hamer, N. A. Hatch, W. Jaffe, R. M. Johnstone, B. R. Mcnamara, C. P. O'Dea, P. Popesso, A. C. Quillen, P. Salomé, C. L. Sarazin, G. M. Voit, R. J. Wilman, M. W. Wise
Physics and Astronomy Faculty Publications
The question of how much gas cools in the cores of clusters of galaxies has been the focus of many, multiwavelength studies in the past 30 years. In this letter we present the first detections of the strongest atomic cooling lines, [Cii], [Oi] and [Nii] in two strong cooling flow clusters, A1068 and A2597, using Herschel-PACS. These spectra indicate that the substantial mass of cold molecular gas (> 109 M⊙) known to be present in these systems is being irradiated by intense UV radiation, most probably from young stars. The line widths of these FIR lines …
Herschel Images Of Ngc 6720: H2 Formation On Dust Grain, P. A. M. Van Hoof, G. C. Van De Steene, M. J. Barlow, K. M. Exter, B. Sibthorpe, T. Ueta, V. Peris, M. A. T. Groenewegen, J. A. D. L. Blommaert, M. Cohen, W. De Meester, Gary J. Ferland, W. K. Gear, H. L. Gomez, P. C. Hargrave, E. Huygen, R. J. Ivison, C. Jean, S. J. Leeks, T. L. Lim, G. Olofsson, E. T. Polehampton, S. Regibo, P. Royer, B. M. Swinyard, B. Vandenbussche, H. Van Winckel, C. Waelkens, H. J. Walker, R. Wesson
Herschel Images Of Ngc 6720: H2 Formation On Dust Grain, P. A. M. Van Hoof, G. C. Van De Steene, M. J. Barlow, K. M. Exter, B. Sibthorpe, T. Ueta, V. Peris, M. A. T. Groenewegen, J. A. D. L. Blommaert, M. Cohen, W. De Meester, Gary J. Ferland, W. K. Gear, H. L. Gomez, P. C. Hargrave, E. Huygen, R. J. Ivison, C. Jean, S. J. Leeks, T. L. Lim, G. Olofsson, E. T. Polehampton, S. Regibo, P. Royer, B. M. Swinyard, B. Vandenbussche, H. Van Winckel, C. Waelkens, H. J. Walker, R. Wesson
Physics and Astronomy Faculty Publications
Herschel PACS and SPIRE images have been obtained of NGC 6720 (the Ring nebula). This is an evolved planetary nebula with a central star that is currently on the cooling track, due to which the outer parts of the nebula are recombining. From the PACS and SPIRE images we conclude that there is a striking resemblance between the dust distribution and the H2 emission, which appears to be observational evidence that H2 forms on grain surfaces. We have developed a photoionization model of the nebula with the Cloudy code which we used to determine the physical conditions of …
Diode Properties Of Nanotube Networks, David D. Allred, Bryan Hicks, Stephanie Getty
Diode Properties Of Nanotube Networks, David D. Allred, Bryan Hicks, Stephanie Getty
Faculty Publications
Single-walled carbon nanotubes (SWCNT) were prepared using iron catalysts deposited by indirect evaporation on silicon substrate covered with 500 nm-thick thermal oxide. Diode SWCNT devices have been fabricated using Au and Al, as the asymmetric metal contacts, and a random network of metallic and semiconducting nanotubes as the device channel. No effort was made to align the SWCNTs or to eliminate metallic nanotubes in our devices. Asymmetric voltage-current behavior was seen. Current rectification was observed in the source-drain bias range of -3 V to +3 V. Rectification was somewhat surprising since, although metallic tubes are in the minority (~ 1/3), …
A Bright Molecular Core In A Crab Nebula Filament, E. D. Loh, J. A. Baldwin, Gary J. Ferland
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 ≥ …
On Arc-Polarized Structures In The Solar Wind, B U. Sonnerup, S E. Haaland, G Paschmann
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 …
A Bare Molecular Cloud At Z ~ 0.45*, Therese M. Jones, Toru Misawa, Jane C. Charlton, Andrew C. Mshar, Gary J. Ferland
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 …
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
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 …
Exotic Smoothness In Four Dimensions And Euclidean Quantum Gravity, Christopher L. Duston
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.
Structure Maps For Hcp Metals From First-Principles Calculations, Gus L. W. Hart, Ohad Levy, Stefano Curtarolo
Structure Maps For Hcp Metals From First-Principles Calculations, Gus L. W. Hart, Ohad Levy, Stefano Curtarolo
Faculty Publications
The ability to predict the existence and crystal type of ordered structures of materials from their components is a major challenge of current materials research. Empirical methods use experimental data to construct structure maps and make predictions based on clustering of simple physical parameters. Their usefulness depends on the availability of reliable data over the entire parameter space. Recent development of high-throughput methods opens the possibility to enhance these empirical structure maps by ab initio calculations in regions of the parameter space where the experimental evidence is lacking or not well characterized. In this paper we construct enhanced maps for …
Co And H3 + Toward Mwc 1080, Mwc 349, And Lkhα 101, Erika Gibb, S. Brittain, T Rettig, M Troutman, Theodore Simon, C Kulesa
Co And H3 + Toward Mwc 1080, Mwc 349, And Lkhα 101, Erika Gibb, S. Brittain, T Rettig, M Troutman, Theodore Simon, C Kulesa
Physics Faculty Works
We present high-resolution, near-infrared NIRSPEC observations of the fundamental rovibrational CO and H+ 3 R(1,0), R(1,1) u , and Q(1,0) transitions toward three early-type young stars: MWC 1080, MWC 349, and LkHα 101. These observations were performed for the purpose of constraining the physical characteristics of the interstellar material along each line of sight. Toward MWC 1080, we detected strong CO absorption and determined a column density upper limit of 1.4 × 1014 cm–2 for H+ 3. We infer that there is very little diffuse material along the line of sight toward MWC 1080 and that the CO absorption is …
Satellite Motion In A Non-Singular Gravitational Potential, Ioannis Haranas, Spiros Pagiatakis
Satellite Motion In A Non-Singular Gravitational Potential, Ioannis Haranas, Spiros Pagiatakis
Physics and Computer Science Faculty Publications
We study the effects of a non-singular gravitational potential on satellite orbits by deriving the corresponding time rates of change of its orbital elements. This is achieved by expanding the non-singular potential into power series up to second order. This series contains three terms, the first been the Newtonian potential and the other two, here R1 (first order term) and R2 (second order term), express deviations of the singular potential from the Newtonian. These deviations from the Newtonian potential are taken as disturbing potential terms in the Lagrange planetary equations that provide the time rates of change of …
Cluster Solver For Dynamical Mean-Field Theory With Linear Scaling In Inverse Temperature, Ehsan Khatami, C. Lee, Z. Bai, R. Scalettar, M. Jarrell
Cluster Solver For Dynamical Mean-Field Theory With Linear Scaling In Inverse Temperature, Ehsan Khatami, C. Lee, Z. Bai, R. Scalettar, M. Jarrell
Faculty Publications
Dynamical mean-field theory and its cluster extensions provide a very useful approach for examining phase transitions in model Hamiltonians and, in combination with electronic structure theory, constitute powerful methods to treat strongly correlated materials. The key advantage to the technique is that, unlike competing real-space methods, the sign problem is well controlled in the Hirsch-Fye (HF) quantum Monte Carlo used as an exact cluster solver. However, an important computational bottleneck remains; the HF method scales as the cube of the inverse temperature, β. This often makes simulations at low temperatures extremely challenging. We present here a method based on determinant …
Quantum Criticality Due To Incipient Phase Separation In The Two-Dimensional Hubbard Model, Ehsan Khatami, K. Mikelsons, D. Galanakis, A. Macridin, J. Moreno, R. Scalettar, M. Jarrell
Quantum Criticality Due To Incipient Phase Separation In The Two-Dimensional Hubbard Model, Ehsan Khatami, K. Mikelsons, D. Galanakis, A. Macridin, J. Moreno, R. Scalettar, M. Jarrell
Faculty Publications
We investigate the two-dimensional Hubbard model with next-nearest-neighbor hopping, t′, using the dynamical cluster approximation. We confirm the existence of a first-order phase-separation transition terminating at a second-order critical point at filling nc(t′) and temperature Tps(t′). We find that as t′ approaches zero, Tps(t′) vanishes and nc(t′) approaches the filling associated with the quantum critical point separating the Fermi liquid from the pseudogap phase. We propose that the quantum critical point under the superconducting dome is the zero-temperature limit of the line of second-order critical points.
Cross Sections Spring 2010, Department Of Physics And Astronomy
Cross Sections Spring 2010, Department Of Physics And Astronomy
Cross Sections
No abstract provided.