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Articles 1321 - 1350 of 2945

Full-Text Articles in Astrophysics and Astronomy

Stellar Mass–Gas-Phase Metallicity Relation At 0.5 ≤ Z ≤ 0.7: A Power Law With Increasing Scatter Toward The Low-Mass Regime, Yicheng Guo, David C. Koo, Yu Lu, John C. Forbes, Marc Rafelski, Jonathan R. Trump, Ricardo Amorín, Guillermo Barro, Romeel Davé, S. M. Faber, Nimish P. Hathi, Hassen Yesuf, Michael C. Cooper, Avishai Dekel, Puragra Guhathakurta, Evan N. Kirby, Anton M. Koekemoer, Pablo G. Pérez-González, Lihwai Lin, Jeffery A. Newman, Joel R. Primack, David J. Rosario, Christopher N. A. Willmer, Renbin Yan May 2016

Stellar Mass–Gas-Phase Metallicity Relation At 0.5 ≤ Z ≤ 0.7: A Power Law With Increasing Scatter Toward The Low-Mass Regime, Yicheng Guo, David C. Koo, Yu Lu, John C. Forbes, Marc Rafelski, Jonathan R. Trump, Ricardo Amorín, Guillermo Barro, Romeel Davé, S. M. Faber, Nimish P. Hathi, Hassen Yesuf, Michael C. Cooper, Avishai Dekel, Puragra Guhathakurta, Evan N. Kirby, Anton M. Koekemoer, Pablo G. Pérez-González, Lihwai Lin, Jeffery A. Newman, Joel R. Primack, David J. Rosario, Christopher N. A. Willmer, Renbin Yan

Physics and Astronomy Faculty Publications

We present the stellar mass (M*)–gas-phase metallicity relation (MZR) and its scatter at intermediate redshifts (0.5 ≤ z ≤ 0.7) for for 1381 field galaxies collected from deep spectroscopic surveys. The star formation rate (SFR) and color at a given M* of this magnitude-limited (R ≲ 24 AB) sample are representative of normal star-forming galaxies. For masses below 109 M☉ our sample of 237 galaxies is ~10 times larger than those in previous studies beyond the local universe. This huge gain in sample size enables superior constraints on the MZR and its scatter …

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Star Formation In Ring Galaxies, Susan C. Olmsted May 2016

Star Formation In Ring Galaxies, Susan C. Olmsted

Undergraduate Honors Theses

Ring galaxies are specific types of interacting galaxies in which a smaller galaxy has passed through the center of the disk of another larger galaxy. The intrusion of the smaller galaxy causes the structure of the larger galaxy to compress as the smaller galaxy falls through, and to recoil back after the smaller galaxy passes through, hence the ring-like shape. In our research, we studied the star-forming regions of a sample of ring galaxies and compared to those of other interacting galaxies and normal galaxies. Using UV, optical, and IR archived images in twelve wavelengths from three telescopes, we analyzed …

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An Apparatus For Studying Electrical Breakdown In Liquid Helium At 0.4 K And Testing Electrode Materials For The Neutron Electric Dipole Moment Experiment At The Spallation Neutron Source, T. M. Ito, J. C. Ramsey, W. Yao, D. H. Beck, V. Cianciolo, S. M. Clayton, Christopher B. Crawford, S. A. Currie, B. W. Filippone, W. C. Griffith, M. Makela, R. Schmid, G. M. Seidel, Z. Tang, D. Wagner, W. Wei, S. E. Williamson Apr 2016

An Apparatus For Studying Electrical Breakdown In Liquid Helium At 0.4 K And Testing Electrode Materials For The Neutron Electric Dipole Moment Experiment At The Spallation Neutron Source, T. M. Ito, J. C. Ramsey, W. Yao, D. H. Beck, V. Cianciolo, S. M. Clayton, Christopher B. Crawford, S. A. Currie, B. W. Filippone, W. C. Griffith, M. Makela, R. Schmid, G. M. Seidel, Z. Tang, D. Wagner, W. Wei, S. E. Williamson

Physics and Astronomy Faculty Publications

We have constructed an apparatus to study DC electrical breakdown in liquid helium at temperatures as low as 0.4 K and at pressures between the saturated vapor pressure and ∼600 Torr. The apparatus can house a set of electrodes that are 12 cm in diameter with a gap of 1–2 cm between them, and a potential up to ±50 kV can be applied to each electrode. Initial results demonstrated that it is possible to apply fields exceeding 100 kV/cm in a 1 cm gap between two electropolished stainless steel electrodes 12 cm in diameter for a wide range of pressures …

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Hallmarks Of The Mott-Metal Crossover In The Hole-Doped Pseudospin-1/2 Mott Insulator Sr2Iro4, Yue Cao, Qiang Wang, Justin A. Waugh, Theodore J. Reber, Haoxiang Li, Xiaoqing Zhou, Stephen Parham, S. -R. Park, Nicholas C. Plumb, Eli Rotenberg, Aaron Bostwick, Jonathan D. Denlinger, Tongfei Qi, Michael A. Hermele, Gang Cao, Daniel S. Dessau Apr 2016

Hallmarks Of The Mott-Metal Crossover In The Hole-Doped Pseudospin-1/2 Mott Insulator Sr2Iro4, Yue Cao, Qiang Wang, Justin A. Waugh, Theodore J. Reber, Haoxiang Li, Xiaoqing Zhou, Stephen Parham, S. -R. Park, Nicholas C. Plumb, Eli Rotenberg, Aaron Bostwick, Jonathan D. Denlinger, Tongfei Qi, Michael A. Hermele, Gang Cao, Daniel S. Dessau

Physics and Astronomy Faculty Publications

The physics of doped Mott insulators remains controversial after decades of active research, hindered by the interplay among competing orders and fluctuations. It is thus highly desired to distinguish the intrinsic characters of the Mott-metal crossover from those of other origins. Here we investigate the evolution of electronic structure and dynamics of the hole-doped pseudospin-1/2 Mott insulator Sr2IrO4. The effective hole doping is achieved by replacing Ir with Rh atoms, with the chemical potential immediately jumping to or near the top of the lower Hubbard band. The doped iridates exhibit multiple iconic low-energy features previously observed …

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H, He-Like Recombination Spectra – I. L-Changing Collisions For Hydrogen, Francisco Guzmán, N. R. Badnell, R. J. R. Williams, P. A. M. Van Hoof, Marios Chatzikos, Gary J. Ferland Apr 2016

H, He-Like Recombination Spectra – I. L-Changing Collisions For Hydrogen, Francisco Guzmán, N. R. Badnell, R. J. R. Williams, P. A. M. Van Hoof, Marios Chatzikos, Gary J. Ferland

Physics and Astronomy Faculty Publications

Hydrogen and helium emission lines in nebulae form by radiative recombination. This is a simple process which, in principle, can be described to very high precision. Ratios of He I and H I emission lines can be used to measure the He+/H+ abundance ratio to the same precision as the recombination rate coefficients. This paper investigates the controversy over the correct theory to describe dipole l-changing collisions (nl → nl′ = l ± 1) between energy-degenerate states within an n-shell. The work of Pengelly & Seaton has, for half-a-century, been considered the definitive …

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Nuclear Effects In The Deuteron And Global Pdf Fits, S. I. Alekhin, S. A. Kulagin, Roberto Petti Apr 2016

Nuclear Effects In The Deuteron And Global Pdf Fits, S. I. Alekhin, S. A. Kulagin, Roberto Petti

Faculty Publications

We present a detailed study of nuclear corrections in the deuteron (D) from an analysis of data from charged-lepton deep-inelastic scattering (DIS) off proton and D, as well as from dimuon pair production in pp and pD collisions and W± and the Z boson production at pp (p¯p) colliders. In particular, we discuss the determination of the off-shell function describing the modification of parton distributions (PDF) in bound nucleons in the context of global PDF fits. Our results are consistent with the ones obtained earlier from the study of the ratios of DIS structure functions A 2 / F …

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Ion Transport Through Macrocapillaries – Oscillations Due To Charge Patch Formation, Dhruva Kulkarni, L.A.M. Lyle, Chad E. Sosolik Apr 2016

Ion Transport Through Macrocapillaries – Oscillations Due To Charge Patch Formation, Dhruva Kulkarni, L.A.M. Lyle, Chad E. Sosolik

Publications

We present results on ion transport through large bore capillaries (macrocapillaries) that probe both the geometric and ion-guided aspects of this ion delivery mechanism. We have demonstrated that guiding in macrocapillaries exhibits position- and angle-dependent transmission properties which are directly related to the capillary material (either metal or insulator) and geometry. Specifically, we have passed 1 keV Rb+ ions through glass and metal macrocapillaries, and have observed oscillations for the transmitted ion current passing through the insulating capillaries. Straightforward calculations show that these oscillations can be attributed to beam deflections from charge patches that form on the interior walls …

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Section Abstracts: Astronomy, Mathematics And Physics Apr 2016

Section Abstracts: Astronomy, Mathematics And Physics

Virginia Journal of Science

Abstracts of the Astronomy, Mathematics, and Physics Section for the 94th Annual Virginia Academy of Science Meeting, May 18-20, 2016, at University of Mary Washington, Fredericksburg, VA.

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Nucleon Pdf Separation With The Collider And Fixed-Target Data, Sergey Alekhin, Johannes Blümlein, Kristin Lohwasser, Lea Michaela Caminada, Katerina Lipka, Ringaile Plačakytė, Sven-Olaf Moch, Roberto Petti Apr 2016

Nucleon Pdf Separation With The Collider And Fixed-Target Data, Sergey Alekhin, Johannes Blümlein, Kristin Lohwasser, Lea Michaela Caminada, Katerina Lipka, Ringaile Plačakytė, Sven-Olaf Moch, Roberto Petti

Faculty Publications

We consider the impact of the recent data obtained by the LHC, Tevatron, and fixed-target experiments on the nucleon quark distributions with a particular focus on disentangling different quark species. An improved determination of the poorly known strange sea distribution is obtained due to including data from the neutrino-induced deep-inelastic scattering experiments NOMAD and CHORUS. The impact of the associated (W + c) production data by CMS and ATLAS on the strange sea determination is also studied and a comparison with earlier results based on the collider data is discussed. Finally, the recent LHC and Tevatron data on …

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Conducting Laalo3/Srtio3 Heterointerfaces On Atomically-Flat Substrates Prepared By Deionized-Water, John G. Connell, J. Nichols, John H. Gruenewald, D. -W. Kim, Sung S. Ambrose Seo Apr 2016

Conducting Laalo3/Srtio3 Heterointerfaces On Atomically-Flat Substrates Prepared By Deionized-Water, John G. Connell, J. Nichols, John H. Gruenewald, D. -W. Kim, Sung S. Ambrose Seo

Physics and Astronomy Faculty Publications

We have investigated how the recently-developed water-leaching method for atomically-flat SrTiO3 (STO) substrates affects the transport properties of LaAlO3 (LAO) and STO heterointerfaces. Using pulsed laser deposition at identical growth conditions, we have synthesized epitaxial LAO thin-films on two different STO substrates, which are prepared by water-leaching and buffered hydrofluoric acid (BHF) etching methods. The structural, transport, and optical properties of LAO/STO heterostructures grown on water-leached substrates show the same high-quality as the samples grown on BHF-etched substrates. These results indicate that the water-leaching method can be used to grow complex oxide heterostructures with atomically well-defined heterointerfaces without …

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Direct Collapse To Supermassive Black Hole Seeds: Comparing The Amr And Sph Approaches, Yang Luo, Kentaro Nagamine, Isaac Shlosman Mar 2016

Direct Collapse To Supermassive Black Hole Seeds: Comparing The Amr And Sph Approaches, Yang Luo, Kentaro Nagamine, Isaac Shlosman

Physics and Astronomy Faculty Publications

We provide detailed comparison between the adaptive mesh refinement (AMR) code ENZO-2.4 and the smoothed particle hydrodynamics (SPH)/N-body code GADGET-3 in the context of isolated or cosmological direct baryonic collapse within dark matter (DM) haloes to form supermassive black holes. Gas flow is examined by following evolution of basic parameters of accretion flows. Both codes show an overall agreement in the general features of the collapse; however, many subtle differences exist. For isolated models, the codes increase their spatial and mass resolutions at different pace, which leads to substantially earlier collapse in SPH than in AMR cases due …

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Disc Outflows And High-Luminosity True Type 2 Agn, Moshe Elitzur, Hagai Netzer Mar 2016

Disc Outflows And High-Luminosity True Type 2 Agn, Moshe Elitzur, Hagai Netzer

Physics and Astronomy Faculty Publications

The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such ‘true type 2 AGN’ are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and …

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En Route To Destruction: The Evolution In Composition Of Ices In Comet D/2012 S1 (Ison) Between 1.2 And 0.34 Au From The Sun As Revealed At Infrared Wavelengths, M. Disanti, B. Bonev, E. Gibb, L. Paganini, G. Villanueva, M. Mumma, J. Keane, G. Blake, N. Russo, K. Meech, R. Vervack, A. Mckay Mar 2016

En Route To Destruction: The Evolution In Composition Of Ices In Comet D/2012 S1 (Ison) Between 1.2 And 0.34 Au From The Sun As Revealed At Infrared Wavelengths, M. Disanti, B. Bonev, E. Gibb, L. Paganini, G. Villanueva, M. Mumma, J. Keane, G. Blake, N. Russo, K. Meech, R. Vervack, A. Mckay

Physics Faculty Works

We report production rates for H2O and eight trace molecules (CO, C2H6, CH4, CH3OH, NH3, H2CO, HCN, C2H2) in the dynamically new, Sun-grazing Comet C/2012 S1 (ISON), using high-resolution spectroscopy at Keck II and the NASA IRTF on 10 pre-perihelion dates encompassing heliocentric distances Rh = 1.21–0.34 AU. Measured water production rates spanned two orders of magnitude, consistent with a long-term heliocentric power law Q(H2O) ${\rm{\propto }}{R}_{{\rm{h}}}^{(-3.1\pm 0.1)}$. Abundance ratios for CO, C2H6, and CH4 with respect to H2O remained constant with Rh and below their corresponding mean values measured among a dominant sample of Oort Cloud comets. CH3OH was …

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Interpreting The Ionization Sequence In Star-Forming Galaxy Emission-Line Spectra, Chris T. Richardson, James T. Allen, Jack A. Baldwin, Paul C. Hewett, Gary J. Ferland, Anthony Crider, Helen Meskhidze Mar 2016

Interpreting The Ionization Sequence In Star-Forming Galaxy Emission-Line Spectra, Chris T. Richardson, James T. Allen, Jack A. Baldwin, Paul C. Hewett, Gary J. Ferland, Anthony Crider, Helen Meskhidze

Physics and Astronomy Faculty Publications

High-ionization star-forming (SF) galaxies are easily identified with strong emission-line techniques such as the BPT diagram, and form an obvious ionization sequence on such diagrams. We use a locally optimally emitting cloud model to fit emission-line ratios that constrain the excitation mechanism, spectral energy distribution, abundances and physical conditions along the star formation ionization sequence. Our analysis takes advantage of the identification of a sample of pure SF galaxies, to define the ionization sequence, via mean field independent component analysis. Previous work has suggested that the major parameter controlling the ionization level in SF galaxies is the metallicity. Here we …

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Trapping Penguins With Entangled B Mesons, Ryan Dadisman, Susan Gardner, Xinshuai Yan Mar 2016

Trapping Penguins With Entangled B Mesons, Ryan Dadisman, Susan Gardner, Xinshuai Yan

Physics and Astronomy Faculty Publications

The first direct observation of time-reversal (T) violation in the system has been reported by the BaBar Collaboration, employing the method of Bañuls and Bernabéu. Given this, we generalize their analysis of the time-dependent T-violating asymmetry (AT) to consider different choices of CP tags for which the dominant amplitudes have the same weak phase. As one application, we find that it is possible to measure departures from the universality of sin⁡(2β) directly. If sin⁡(2β) is universal, as in the Standard Model, the method permits the direct determination of penguin effects in these channels. …

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Orion's Veil. Iv. H2 Excitation And Geometry, N. P. Abel, Gary J. Ferland, C. R. O'Dell, Thomas H. Troland Mar 2016

Orion's Veil. Iv. H2 Excitation And Geometry, N. P. Abel, Gary J. Ferland, C. R. O'Dell, Thomas H. Troland

Physics and Astronomy Faculty Publications

The foreground Veil of material that lies in front of the Orion Nebula is the best studied sample of the interstellar medium because we know where it is located, how it is illuminated, and the balance of thermal and magnetic energy. In this work, we present high-resolution STIS observations toward the Trapezium, with the goal of better understanding the chemistry and geometry of the two primary Veil layers, along with ionized gas along the line of sight. The most complete characterization of the rotational/vibrational column densities of H2 in the almost purely atomic components of the Veil are presented, …

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The Search For Dark Matter Annihilation In Galaxy Clusters At Veritas, James V. Tucci Mar 2016

The Search For Dark Matter Annihilation In Galaxy Clusters At Veritas, James V. Tucci

Open Access Dissertations

Recent data and cosmological models point to a significant fraction of the Universe being comprised of Cold Dark Matter (DM), though little is known about it directly as it does not interact electromagnetically. The most likely explanation for DM is a Weakly Interacting Massive Particle (WIMP) having a mass as low as ∼10 GeV to as high as ∼10 TeV. WIMPs are believed to be their own antiparticles and self-annihilate into a variety of lighter particles including γ-rays. Many direct detection, indirect detection, and direct production schemes have been proposed to search for the elusive WIMP. Galaxy clusters, consisting of …

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Development, Evaluation, And Validation Of A High-Resolution Directivity Measurement System For Played Musical Instruments, K Joshua Bodon Mar 2016

Development, Evaluation, And Validation Of A High-Resolution Directivity Measurement System For Played Musical Instruments, K Joshua Bodon

Theses and Dissertations

A high-resolution directivity measurement system at Brigham Young University has been renovated and upgraded. Acoustical treatments have been installed on the microphone array, professional-grade audio hardware and cabling have been utilized, and user-friendly MATLAB processing and plotting codes have been developed. The directivities of 16 played musical instruments and several loudspeakers have been measured by the system, processed, and plotted. Using loudspeakers as simulated musicians, a comprehensive analysis was completed to validate the system and understand its error bounds. A comparison and evaluation of repeated-capture to single-capture spherical systems was made to demonstrate the high level of detail provided by …

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Improvements To The Two-Point In Situ Method For Measurement Of The Room Constant And Sound Power In Semi-Reverberant Rooms, Zachary R. Jensen Mar 2016

Improvements To The Two-Point In Situ Method For Measurement Of The Room Constant And Sound Power In Semi-Reverberant Rooms, Zachary R. Jensen

Theses and Dissertations

The two-point in situ method is a technique for measuring the room constant of a semi-reverberant room and the sound power of a source in that room simultaneously using two measurement positions. Using a reference directivity source, where the directivity factor along any given axis of the source has been measured, one is able to use the Hopkins-Stryker equation to measure both the room constant and the sound power level of another source rather simply. Using both numerical and experimental data, it was found that by using generalized energy density (GED) as a measurement quantity, the results were more accurate …

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Scale Invariant Jet Suppression Across The Black Hole Mass Scale, David Garofalo, Chandra B. Singh Mar 2016

Scale Invariant Jet Suppression Across The Black Hole Mass Scale, David Garofalo, Chandra B. Singh

Faculty Articles

We provide a schematic framework for understanding observations of jet suppression in soft state black hole X-ray binaries based on the Blandford-Payne process and the net magnetic flux threading the black hole. Due to the geometrical thinness of soft state disks, mass-loading of field lines is ineffective compared to both geometrically thick disks as well as thin disks with greater black hole threading flux, a simple physical picture that allows us to understand the weakness of jets in radiatively efficient thin disks accreting in the prograde direction around high-spinning black holes. Despite a simplicity that forbids insights into the complexity …

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On R - W1 As A Diagnostic To Discover Obscured Active Galactic Nuclei In Wide-Area X-Ray Surveys, Stephanie M. Lamassa, Francesca Civano, Marcella Brusa, Daniel Stern, Eilat Glikman, Sarah Gallagher, C. Meg Urry, Sabrina Cales, Nico Cappelluti, Carolin Cardamone, Andrea Comastri, Duncan Farrah, Jenny E. Greene, S. Komossa, Andrea Merloni, Tony Mroczkowski, Priyamvada Natarajan, Gordon Richards, Mara Salvato, Kevin Schawinski, Ezequiel Treister Feb 2016

On R - W1 As A Diagnostic To Discover Obscured Active Galactic Nuclei In Wide-Area X-Ray Surveys, Stephanie M. Lamassa, Francesca Civano, Marcella Brusa, Daniel Stern, Eilat Glikman, Sarah Gallagher, C. Meg Urry, Sabrina Cales, Nico Cappelluti, Carolin Cardamone, Andrea Comastri, Duncan Farrah, Jenny E. Greene, S. Komossa, Andrea Merloni, Tony Mroczkowski, Priyamvada Natarajan, Gordon Richards, Mara Salvato, Kevin Schawinski, Ezequiel Treister

Physics and Astronomy Publications

Capitalizing on the all-sky coverage of WISE and the 35% and 50% sky coverage from Sloan Digital Sky Survey and Pan-STARRS, respectively, we explore the efficacy of mR (optical) - (mid-infrared), hereafter , as a color diagnostic to identify obscured supermassive black hole accretion in wide-area X-ray surveys. We use the ∼16.5 deg2 Stripe 82 X-ray survey data as a test bed to compare with R - K, an oft-used obscured active galactic nucleus (AGN) selection criterion, and examine where different classes of objects lie in this parameter space. Most stars follow a well-defined path in R - K versus …

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Optically Detected Magnetic Resonance Of Silicon Vacancies In Sic: Predicting Resonance Of Cylindrical Cavities, Kyle Miller, John Colton Feb 2016

Optically Detected Magnetic Resonance Of Silicon Vacancies In Sic: Predicting Resonance Of Cylindrical Cavities, Kyle Miller, John Colton

Journal of Undergraduate Research

Optically Detected Magnetic Resonance is one method of performing Electron Spin Resonance (ESR) on a material. ESR is used to determine the electron spin lifetime of a material, an important parameter for use in quantum computing. Resonant cavities are conducting containers that are frequently used in ESR to create a strong magnetic field near the sample. As such it is valuable to design a resonant cavity and predict its resonant frequency. Cylindrical cavities modified with dielectric resonators (DRs) are viable for such experiments.

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Exploring The Weak Mach Reflection Regime, Kevin Leete, Dr. Kent Gee Feb 2016

Exploring The Weak Mach Reflection Regime, Kevin Leete, Dr. Kent Gee

Journal of Undergraduate Research

When a shock wave reflects off a rigid surface with certain combinations of incident shock strength and angle, a Mach reflection can occur. This is when portions of the incident and reflected waves merge to create a stronger shock called a Mach stem that travels parallel to the reflecting surface. This phenomenon has been studied extensively for two extreme cases: large outdoor explosions and small, laboratory experiments of weak shocks. The purpose of this project was to design and execute an outdoor experiment where this phenomenon could be observed by microphones as well as high speed video imaging to detect …

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Evaluating The Efficacy Of Gravitational Wave Games In Arousing Interest And Promoting Understanding Of Gravitational Wave Research, Jonathan Wheeler Feb 2016

Evaluating The Efficacy Of Gravitational Wave Games In Arousing Interest And Promoting Understanding Of Gravitational Wave Research, Jonathan Wheeler

Posters, Presentations, and Papers

The LIGO Scientific Collaboration’s Education and Public Outreach Group seeks to ameliorate the lack of public understanding of gravitational wave physics. I present the results of a set of pre-tests and post-tests from a public high school which measures Black Hole Pong’s effectiveness in teaching the concepts and benefits of gravitational wave astronomy. Results of this test can be used in the development of other outreach games, such as Black Hole Master and Chickens in Space.

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Growth Control Of Oxygen Stoichiometry In Homoepitaxial Srtio3 Films By Pulsed Laser Epitaxy In High Vacuum, Ho Nyung Lee, Sung S. Ambrose Seo, Woo Seok Choi, Christopher M. Rouleau Jan 2016

Growth Control Of Oxygen Stoichiometry In Homoepitaxial Srtio3 Films By Pulsed Laser Epitaxy In High Vacuum, Ho Nyung Lee, Sung S. Ambrose Seo, Woo Seok Choi, Christopher M. Rouleau

Physics and Astronomy Faculty Publications

In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on …

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Reconciling Ag-Star Formation, The Soltan Argument, And Meier's Paradox, David Garofalo, Matthew I. Kim, Damian J. Christian, Emily Hollingworth Jan 2016

Reconciling Ag-Star Formation, The Soltan Argument, And Meier's Paradox, David Garofalo, Matthew I. Kim, Damian J. Christian, Emily Hollingworth

Faculty Articles

We provide a theoretical context for understanding the recent work of Kalfountzou et al. showing that star formation is enhanced at lower optical luminosity in radio-loud quasars. Our proposal for coupling the assumption of collimated FRII quasar-jet-induced star formation with lower accretion optical luminosity also explains the observed jet power peak in active galaxies at higher redshift compared to the peak in accretion power, doing so in a way that predicts the existence of a family of radio-quiet active galactic nuclei associated with rapidly spinning supermassive black holes at low redshift, as mounting observations suggest. The relevance of this work …

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The Jcmt Nearby Galaxies Legacy Survey – X. Environmental Effects On The Molecular Gas And Star Formation Properties Of Spiral Galaxies, Angus Mok, C. D. Wilson, J. Golding, B. E. Warren, F. P. Israel, S. Serjeant, J. H. Knapen, José R. Sánchez-Gallego, P. Barmby, G. J. Bendo, E. Rosolowsky, P. Van Der Werf Jan 2016

The Jcmt Nearby Galaxies Legacy Survey – X. Environmental Effects On The Molecular Gas And Star Formation Properties Of Spiral Galaxies, Angus Mok, C. D. Wilson, J. Golding, B. E. Warren, F. P. Israel, S. Serjeant, J. H. Knapen, José R. Sánchez-Gallego, P. Barmby, G. J. Bendo, E. Rosolowsky, P. Van Der Werf

Physics and Astronomy Faculty Publications

We present a study of the molecular gas properties in a sample of 98 H I – flux selected spiral galaxies within ∼25 Mpc, using the CO J = 3 − 2 line observed with the James Clerk Maxwell Telescope. We use the technique of survival analysis to incorporate galaxies with CO upper limits into our results. Comparing the group and Virgo samples, we find a larger mean H2 mass in the Virgo galaxies, despite their lower mean H I mass. This leads to a significantly higher H2 to H I ratio for Virgo galaxies. Combining our data …

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How Uncertainty In The Neutral Wind Limits The Accuracy Of Ionospheric Modeling And Forecasting, Michael David, Jan J. Sojka, Robert W. Schunk Jan 2016

How Uncertainty In The Neutral Wind Limits The Accuracy Of Ionospheric Modeling And Forecasting, Michael David, Jan J. Sojka, Robert W. Schunk

Publications

One of the most important input fields for an ionospheric model is the horizontal neutral wind. The primary mechanism by which the neutral wind affects ionospheric densities is the inducement of an upward or downward ion drift along the magnetic field lines; this affects the rate at which ions are lost through recombination. The magnitude of this effect depends upon the dip angle of the magnetic field; for this reason, the impact of the neutral wind is somewhat less in polar regions than at mid-latitudes. It is unfortunate that observations of the neutral wind are relatively scarce, as compared for …

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Robert Gowdy On Ripples In Space-Time, Dan Gaitanis Jan 2016

Robert Gowdy On Ripples In Space-Time, Dan Gaitanis

AUCTUS: The Journal of Undergraduate Research and Creative Scholarship

In February, a team of scientists announced that they had detected the sound of two black holes, some billion light years away, and that it confirmed the last part of Albert Einstein’s “Theory of Relativity.” It was a very faint sound, picked up by two detectors in the United States.

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An Automated System To Measure The Quantum Efficiency Of Ccds For Astronomy, Rebecca Ann Coles Jan 2016

An Automated System To Measure The Quantum Efficiency Of Ccds For Astronomy, Rebecca Ann Coles

Wayne State University Dissertations

We describe a system to measure the Quantum Efficiency in the wavelength range of 300nm to 1100nm of 40x40 mm n-channel CCD sensors for the construction of the 3.2 gigapixel LSST focal plane. The technique uses a series of instruments to create a very uniform flux of photons of controllable intensity in the wavelength range of interest across the face the sensor. This allows the absolute Quantum Efficiency to be measured with an accuracy in the 1% range. This system will be part of a production facility at Brookhaven National Lab for the basic component of the LSST camera.

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