Astrophysics and Astronomy Commons^™

Coherent Network Analysis For Continuous Gravitational Wave Signals In A Pulsar Timing Array: Pulsar Phases As Extrinsic Parameters, Yan Wang, Soumya D. Mohanty, F. A. Jenet

Physics & Astronomy Faculty Publications

Supermassive black hole binaries are one of the primary targets of gravitational wave (GW) searches using pulsar timing arrays (PTAs). GW signals from such systems are well represented by parameterized models, allowing the standard Generalized Likelihood Ratio Test (GLRT) to be used for their detection and estimation. However, there is a dichotomy in how the GLRT can be implemented for PTAs: there are two possible ways in which one can split the set of signal parameters for semi-analytical and numerical extremization. The straightforward extension of the method used for continuous signals in ground-based GW searches, where the so-called pulsar phase …

Di-Hadron Correlations With Identified Leading Hadrons In 200 Gev Au + Au And D + Au Collisions At Star, James K. Adkins, Renee H. Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, X. Bai

Physics and Astronomy Faculty Publications

The STAR Collaborationpresents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au+Au and minimum-bias d+Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au + Au data with respect to the d + Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. …

On Calculating The Current-Voltage Characteristic Of Multi-Diode Models For Organic Solar Cells, Ken Roberts, Sree Ram Valluri

Physics and Astronomy Publications

We provide an alternative formulation of the exact calculation of the current-voltage characteristic of solar cells which have been modeled with a lumped parameters equivalent circuit with one or two diodes. Such models, for instance, are suitable for describing organic solar cells whose current-voltage characteristic curve has an inflection point, also known as an S-shaped anomaly. Our formulation avoids the risk of numerical overflow in the calculation. It is suitable for implementation in Fortran, C or on micro-controllers.

The Young Solar Analogs Project. I. Spectroscopic And Photometric Methods And Multi-Year Timescale Spectroscopic Results, R. O. Gray, Jon M. Saken, C. J. Corbally, M. M. Briley, R. A. Lambert, I. M. Newsome, M. F. Seeds, Y. Kahvaz

Physics Faculty Research

This is the first in a series of papers presenting methods and results from the Young Solar Analogs Project, which began in 2007. This project monitors both spectroscopically and photometrically a set of 31 young (300–1500 Myr) solar-type stars with the goal of gaining insight into the space environment of the Earth during the period when life first appeared. From our spectroscopic observations we derive the Mount Wilson S chromospheric activity index (SMW), and describe the method we use to transform our instrumental indices to SMW without the need for a color term. We introduce three photospheric …

Gamma-Rays From The Quasar Pks 1441+25: Story Of An Escape, P. T. Reynolds, Et Al

Physical Sciences Publications

Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the universe. The detection of significant emission above 100 GeV from a distant quasar would show that some of the radiated gamma-rays escape pair-production interactions with low-energy photons, be it the extragalactic background light (EBL), or the radiation near the supermassive black hole lying at the jet's base. VERITAS detected gamma-ray emission up to ~200 GeV from PKS 1441+25 (z = 0.939) during 2015 April, a period of high activity across all wavelengths. This observation of …

From JEff=1/2 Insulator To P-Wave Superconductor In Single-Crystal Sr2Ir1−XRuXO4 (0≤X≤1), Shujuan Yuan, Saicharan Aswartham, Jsaminka Terzic, H. Zheng, H. D. Zhao, P. Schlottmann, Gang Cao

Physics and Astronomy Faculty Publications

Sr₂IrO₄ is a magnetic insulator assisted by strong spin-orbit coupling (SOC) whereas Sr₂RuO₄ is a p-wave superconductor. The contrasting ground states have been shown to result from the critical role of the strong SOC in the iridate. Our investigation of structural, transport, and magnetic properties reveals that substituting 4dRu⁴⁺(4d⁴) ions for 5dIr⁴⁺(5d⁵) ions in Sr₂IrO₄ directly adds holes to the t_2g bands, reduces the SOC, and thus rebalances the competing energies in single-crystal Sr …

Supermassive Black Hole Seed Formation At High Redshifts: Long-Term Evolution Of The Direct Collapse, Isaac Shlosman, Jun-Hwan Choi, Mitchell C. Begelman, Kentaro Nagamine

Physics and Astronomy Faculty Publications

We use cosmological adaptive mesh refinement code enzo zoom-in simulations to study the long-term evolution of the collapsing gas within dark matter haloes at z. This direct collapse process is a leading candidate for rapid formation of supermassive black hole (SMBH) seeds. To circumvent the Courant condition at small radii, we apply the sink particle method, focusing on evolution on scales ∼0.01–10 pc. The collapse proceeds in two stages, with the secondary runaway happening within the central 10 pc. The sink particles form when the collapsing gas requires additional refinement of the grid size at the highest refinement level. …

A Continuum From Clear To Cloudy Hot-Jupiter Exoplanets Without Primordial Water Depletion, David K. Sing, Jonathan J. Fortney, Nikolay Nikolov, Hannah R. Wakeford, Tiffany Kataria, Thomas M. Evans, Suzanne Aigrain, Gilda E. Ballester, Adam Burrows, Drake Deming, Jean-Michel Désert, Neale P. Gibson, Gregory W. Henry, Catherine M. Huitson, Heather A. Knutson, Alain Lecavelier Des Etangs, Frederic Pont, Adam P. Showman, Alfred Vidal-Madjar, Michael H. Williamson, Paul A. Wilson

Information Systems and Engineering Management Research Publications

Thousands of transiting exoplanets have been discovered, but spectral analysis of their atmospheres has so far been dominated by a small number of exoplanets and data spanning relatively narrow wavelength ranges (such as 1.1–1.7 micrometres). Recent studies show that some hot-Jupiter exoplanets have much weaker water absorption features in their near-infrared spectra than predicted. The low amplitude of water signatures could be explained by very low water abundances, which may be a sign that water was depleted in the protoplanetary disk at the planet’s formation location, but it is unclear whether this level of depletion can actually occur. Alternatively, these …

Observation Of Transverse Spin-Dependent Azimuthal Correlations Of Charged Pion Pairs In P↑+P At √S=200  Gev, James K. Adkins, Renee H. Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev

Physics and Astronomy Faculty Publications

We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in p^↑+p collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of 5 standard deviations at high transverse momenta, at high pseudorapidities η>0.5, and for pair masses around the mass of the ρ meson. This is the first direct transversity measurement in p+p collisions.

The Mimes Survey Of Magnetism In Massive Stars: Introduction And Overview, G. A. Wade, C. Neiner, E. Alecian, H. H. Grunhunt, V. Petit, B. Batz, D. A. Bohlender, D. H. Cohen, H. F. Henrichs, O. Kochukhov, J. D. Landstreet, N. Manset, F. Martins, S. Mathis, M. E. Oksala, S. P. Owocki, Th. Rivinius, M. E. Schultz, J. O. Sundqvist, R. H.D. Townsend, A. Doula, J. C. Bouret, J. Braithwaite, M. Briquet, A. C. Carciofi, A. David-Uraz, C. P. Folsom, A. W. Fullerton, B. Leroy, W. L.F. Marcolino, A. F.J. Moffat, Y. Naze, N. St Louis, M. Auriere, S. Bagnulo, J. D. Bailey, R. H. Barba, A. Blazere, T. Bohm, C. Catala, J-F Donati, L. Ferrario, D. Harrington, I. D. Howarth, Richard Ignace, L. Kaper, T. Luftinger, R. Prinja, J. S. Vink, W. W. Weiss, I. Yakunin

ETSU Faculty Works

The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in 2008 and completed in 2013, the project was supported by three Large Program allocations, as well as various programmes initiated by independent principal investigators, and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada–France–Hawaii Telescope, Narval at the Télescope Bernard Lyot and HARPSpol at the European Southern Observatory La Silla 3.6 m …

The Nustar Extragalactic Survey: First Direct Measurements Of The Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At Z > 0.1, J. Aird, D. M. Alexander, D. R. Ballantyne, R. C. Hickox, A. Del-Moro, R. C. Hickox, G. B. Lansbury, J. R. Mullaney, F. E. Bauer, W. N. Brandt

Dartmouth Scholarship

We present the first direct measurements of the rest-frame 10–40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1 < z < 3, selected at 8–24 keV energies from sources in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of …

On The Stellar Companion To The Exoplanet Hosting Star 30 Arietis B, S. R. Kane, T. Barclay, M. Hartmann, A. P. Hatzes, Eric L. N. Jensen, D. R. Ciardi, D. Huber, J. T. Wright, E. V. Quintana

Physics & Astronomy Faculty Works

A crucial aspect of understanding planet formation is determining the binarity of the host stars. Results from radial velocity (RV) surveys and the follow-up of Kepler exoplanet candidates have demonstrated that stellar binarity certainly does not exclude the presence of planets in stable orbits and the configuration may in fact be relatively common. Here we present new results for the 30 Arietis system which confirms that the B component hosts both planetary and stellar companions. Keck AO imaging provides direct detection of the stellar companion and additional RV data are consistent with an orbiting star. We present a revised orbit …

Relative Proper Motions In The Rho Ophiuchi Cluster, Bruce Wilking, Frederick Vrba, Timothy Sullivan

Physics Faculty Works

Near-infrared images optimized for astrometry have been obtained for four fields in the high-density L 1688 cloud core over a 12 year period. The targeted regions include deeply embedded young stellar objects (YSOs) and very low luminosity objects too faint and/or heavily veiled for spectroscopy. Relative proper motions in R.A. and decl. were computed for 111 sources and again for a subset of 65 YSOs, resulting in a mean proper motion of (0,0) for each field. Assuming each field has the same mean proper motion, YSOs in the four fields were combined to yield estimates of the velocity dispersions in …

An Organic Mixed Ion-Electron Conductor For Power Electronics, Abdellah Malti, Jesper Edberg, Hjalmar Granberg, Zia Ullah Khan, Jens W. Andreasen, Xianjie Liu, Dan Zhao, Hao Zhang, Yulong Yao, Joseph W. Brill, Isak Engquist, Mats Fahlman, Lars Wågberg, Xavier Crispin, Magnus Berggren

Physics and Astronomy Faculty Publications

A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting nanopaper are exploited in devices which exhibit record values for the charge storage capacitance (1F) in supercapacitors and transconductance (1S) in electrochemical transistors.

Observation Of Transverse Spin-Dependent Azimuthal Correlations Of Charged Pion Pairs In P + P At Sqrt(S) = 200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration

Physics and Astronomy Faculty Publications

No abstract provided.

Differentialgeometry In Brno, Ian M. Anderson

Presentations

This page will provide files supporting Ian Anderson's presentations in Brno, December 2015. The files can be found and downloaded from "Additional Files", below.

The files include:

(1) DifferentialGeometryUSU.mla: This is the Maple Library Archive file which provides all the DifferentialGeometry functionality. Here are Installation Instructions.

(2) DifferentialGeometry.help : this is the latest version of the DifferentialGeometry documentation. Copy this file to the same directory used for DifferentialGeometryUSU.mla (from step (1)).

Using Protoplanetary Disks To Weigh The Youngest Stars And Constrain The Earliest Stages Of Stellar Evolution, I. Czekala, S. Andrews, Eric L. N. Jensen, K. Stassun, D. W. Latham, D. Wilner, G. Torres

Physics & Astronomy Faculty Works

Mass is the fundamental property that determines the fate of a star. In particular, the masses of young stars are of great relevance to many astrophysical problems, including star and planet formation. We have developed a novel approach that combines spatially resolved sub-millimeter spectral line imaging and optical/near-infrared high resolution spectroscopy to derive the fundamental properties of a young star: mass, temperature, and radius. By applying our technique to a sample of pre-main sequence stars, we are mapping out a dynamically-calibrated Hertzsprung-Russell diagram for the express purpose of evaluating pre-main sequence evolutionary models. Looking forward, ALMA is poised to deliver …

Electronic Structure And Insulating Gap In Epitaxial Vo2 Polymorphs, Shinbuhm Lee, Tricia L. Meyer, Changhee Sohn, Donghwa Lee, John Nichols, Dongkyu Lee, Sung S. Ambrose Seo, John W. Freeland, Tae Won Noh, Ho Nyung Lee

Physics and Astronomy Faculty Publications

Determining the origin of the insulating gap in the monoclinic VO₂(M1) is a long-standing issue. The difficulty of this study arises from the simultaneous occurrence of structural and electronic transitions upon thermal cycling. Here, we compare the electronic structure of the M1 phase with that of single crystalline insulating VO₂(A) and VO₂(B) thin films to better understand the insulating phase of VO₂. As these A and B phases do not undergo a structural transition upon thermal cycling, we comparatively study the origin of the gap opening in the insulating VO₂ phases. …

Scalable Synthesis And Energy Applications Of Defect Engineered Nano Materials, Mehmet Karakaya

All Dissertations

Nanomaterials and nanotechnologies have attracted a great deal of attention in a few decades due to their novel physical properties such as, high aspect ratio, surface morphology, impurities, etc. which lead to unique chemical, optical and electronic properties. The awareness of importance of nanomaterials has motivated researchers to develop nanomaterial growth techniques to further control nanostructures properties such as, size, surface morphology, etc. that may alter their fundamental behavior. Carbon nanotubes (CNTs) are one of the most promising materials with their rigidity, strength, elasticity and electric conductivity for future applications. Despite their excellent properties explored by the abundant research works, …

Quiet-Sun Network Bright Point Phenomena With Sigmoidal Signatures, David L. Chesney, Hakeem M. Oluşeyi, Norton Brice Orange, Patrick R. Champey

Aerospace, Physics, and Space Science Faculty Publications

Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quietSun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions …