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2018

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Articles 151 - 180 of 440

Full-Text Articles in Astrophysics and Astronomy

Three-Dimensional Hybrid Simulation Of Viscous-Like Processes At Saturn's Magnetosphere Boundary, P. A. Delamere, B. Burkholder, X. Ma Aug 2018

Three-Dimensional Hybrid Simulation Of Viscous-Like Processes At Saturn's Magnetosphere Boundary, P. A. Delamere, B. Burkholder, X. Ma

Publications

Saturn's magnetosheath flows exhibit significant dawn/dusk asymmetry. The dawnside flows are reduced from expectation, suggesting significant momentum transport through the magnetopause boundary where the flow shear is maximized. It has been suggested that the solar wind interaction with the giant magnetospheres is, in fact, dominated by a viscous‐like interaction governed by the Kelvin‐Helmholtz instability. In three dimensions, the Kelvin‐Helmholtz instability can generate small‐scale and intermittent magnetic reconnection due, in part, to a twisted magnetic field topology. The net result is a field line threading of the magnetopause boundary and the generation of Maxwell shear stresses. Here we present three‐dimensional hybrid …

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Astromimetics: The Dawn Of A New Era For (Bio)Materials Science?, Vuk Uskoković, Victoria M. Wu Aug 2018

Astromimetics: The Dawn Of A New Era For (Bio)Materials Science?, Vuk Uskoković, Victoria M. Wu

Pharmacy Faculty Articles and Research

Composite, multifunctional fine particles are likely to be at the frontier of materials science in the foreseeable future. Here we present a submicron composite particle that mimics the stratified structure of the Earth by having a zero-valent iron core, a silicate/silicide mantle, and a thin carbonaceous crust resembling the biosphere and its biotic deposits. Particles were formulated in a stable colloidal form and made to interact with various types of healthy and cancer cells in vitro. A selective anticancer activity was observed, promising from the point of view of the intended use of the particles for tumor targeting across the …

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Ttv-Determined Masses For Warm Jupiters And Their Close Planetary Companions, Dong-Hong Wu, Songhu Wang, Ji-Lin Zhou, Jason H. Steffen, Gregory Laughlin Aug 2018

Ttv-Determined Masses For Warm Jupiters And Their Close Planetary Companions, Dong-Hong Wu, Songhu Wang, Ji-Lin Zhou, Jason H. Steffen, Gregory Laughlin

Physics & Astronomy Faculty Research

Although the formation and the properties of hot Jupiters (with orbital periods P < 10 days) have attracted a great deal of attention, the origins of warm Jupiters (10 < P < 100 days) are less well studied. Using a transit timing analysis, we present the orbital parameters of five planetary systems containing warm Jupiters, Kepler 30, Kepler 117, Kepler 302, Kepler 487, and Kepler 418. Three of them, Kepler-30 c(M p = 549.4 ± 5.6 M ⊕), Kepler-117 c(M p = 702 ± 63 M ⊕), and Kepler 302 c(M p = 933 ± 527 M ⊕), are confirmed to be real warm Jupiters based on their mass. Insights drawn from the radius–temperature relationship lead to the inference that hot Jupiters and warm Jupiters can be roughly separated by T eff,c = 1123.7 ± 3.3 K. Also, T eff,c provides a good separation for Jupiters with companion fraction consistent with zero (T eff > T eff,c) and those with companion fraction significantly different from zero (T eff < T eff,c).

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A Deficit Of Dark Matter From Jeans Modeling Of The Ultra-Diffuse Galaxy Ngc 1052-Df2, Asher Wasserman, Aaron Romanowsky, Jean Brodie, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Yotam Cohen, Shany Danieli Aug 2018

A Deficit Of Dark Matter From Jeans Modeling Of The Ultra-Diffuse Galaxy Ngc 1052-Df2, Asher Wasserman, Aaron Romanowsky, Jean Brodie, Pieter Van Dokkum, Charlie Conroy, Roberto Abraham, Yotam Cohen, Shany Danieli

Faculty Publications

The discovery of the ultra-diffuse galaxy NGC 1052-DF2 and its peculiar population of star clusters has raised new questions about the connections between galaxies and dark matter (DM) halos at the extremes of galaxy formation. In light of debates over the measured velocity dispersion of its star clusters and the associated mass estimate, we constrain mass models of DF2 using its observed kinematics with a range of priors on the halo mass. Models in which the galaxy obeys a standard stellar-halo mass relation are in tension with the data and also require a large central density core. Better fits are …

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A Search For Possible Long Range Spin Dependent Interactions Of The Neutron From Exotic Vector Boson Exchange, C. Haddock, J. Amadio, E. Anderson, L. Barrón-Palos, B. Crawford, Christopher B. Crawford, D. Esposito, W. Fox, I. Francis, J. Fry, H. Gardiner, A. Holley, K. Korsak, J. Lieffers, S. Magers, M. Maldonado-Velázquez, D. Mayorov, J. S. Nico, T. Okudaira, C. Paudel, S. Santra, M. Sarsour, H. M. Shimizu, W. M. Snow, Aaron P. Sprow, K. Steffen, H. E. Swanson, F. Tovesson, J. Vanderwerp, P. A. Yergeau Aug 2018

A Search For Possible Long Range Spin Dependent Interactions Of The Neutron From Exotic Vector Boson Exchange, C. Haddock, J. Amadio, E. Anderson, L. Barrón-Palos, B. Crawford, Christopher B. Crawford, D. Esposito, W. Fox, I. Francis, J. Fry, H. Gardiner, A. Holley, K. Korsak, J. Lieffers, S. Magers, M. Maldonado-Velázquez, D. Mayorov, J. S. Nico, T. Okudaira, C. Paudel, S. Santra, M. Sarsour, H. M. Shimizu, W. M. Snow, Aaron P. Sprow, K. Steffen, H. E. Swanson, F. Tovesson, J. Vanderwerp, P. A. Yergeau

Physics and Astronomy Faculty Publications

We present a search for possible spin dependent interactions of the neutron with matter through exchange of spin 1 bosons with axial vector couplings as envisioned in possible extensions of the Standard Model. This was sought using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that interactions would tilt the plane of polarization and develop a component along the neutron momentum. The result for the rotation angle, ϕ′=[2.8±4.6(stat.)±4.0(sys.)]×10−5 rad/m is consistent with zero. This result improves the upper bounds on the neutron-matter coupling g2A …

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Correlation Measurements Between Flow Harmonics In Au + Au Collisions At Rhic, J. Adam, L. Adamczyk, J. R. Adams, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, F. Atetalla, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. J. Bassill, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, Renee H. Fatemi, Suvarna Ramachandran Aug 2018

Correlation Measurements Between Flow Harmonics In Au + Au Collisions At Rhic, J. Adam, L. Adamczyk, J. R. Adams, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, F. Atetalla, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. J. Bassill, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

Flow harmonics (vn) in the Fourier expansion of the azimuthal distribution of particles are widely used to quantify the anisotropy in particle emission in high-energy heavy-ion collisions. The symmetric cumulants, SC(m,n), are used to measure the correlations between different orders of flow harmonics. These correlations are used to constrain the initial conditions and the transport properties of the medium in theoretical models. In this Letter, we present the first measurements of the four-particle symmetric cumulants in Au+Au collisions at √sNN=39 and 200 GeV from data collected by the …

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Circumbinary Discs Around Merging Stellar-Mass Black Holes, Rebecca G. Martin, Chris Nixon, Fu-Guo Xie, Andrew King Aug 2018

Circumbinary Discs Around Merging Stellar-Mass Black Holes, Rebecca G. Martin, Chris Nixon, Fu-Guo Xie, Andrew King

Physics & Astronomy Faculty Research

A circumbinary disc around a pair of merging stellar-mass black holes may be shocked and heated during the recoil of the merged hole, causing a near-simultaneous electromagnetic counterpart to the gravitational wave event. The shocks occur around the recoil radius, where the disc orbital velocity is equal to the recoil velocity. The amount of mass present near this radius at the time of the merger is critical in determining how much radiation is released. We explore the evolution of a circumbinary disc in two limits. First, we consider an accretion disc that feels no torque from the binary. The disc …

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Fourier Transform Spectroscopy Of The C³Δ-X³Δ Transition Of Tio In Support Of Exoplanet Spectroscopy, James N. Hodges, Peter Bernath Aug 2018

Fourier Transform Spectroscopy Of The C³Δ-X³Δ Transition Of Tio In Support Of Exoplanet Spectroscopy, James N. Hodges, Peter Bernath

Chemistry & Biochemistry Faculty Publications

Recent limitations in the TiO line list used in cross-correlation detection schemes have made the detection and quantification of TiO in exoplanetary atmospheres challenging. The quality of the line list appears to degrade at wavelengths shorter than 630 nm. The C3Δ-X3Δ electronic transition has strong rovibronic bands near 500 nm. In an effort to improve the line list, a spectrum of TiO in a furnace at 1950 K is analyzed, and the assigned lines of the C3Δ-X3Δ transition are fit with the N2 Hamiltonian in the molecular spectrum fitting software, PGOPHER …

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Shocks Or Photoionization: Direct Temperature Measurements Of The Low-Ionization Gas In Quiescent Galaxies, Renbin Yan Aug 2018

Shocks Or Photoionization: Direct Temperature Measurements Of The Low-Ionization Gas In Quiescent Galaxies, Renbin Yan

Physics and Astronomy Faculty Publications

The ionization mechanism of the low-ionization gas in quiescent red-sequence galaxies has been a long-standing puzzle. Direct temperature measurements would put strong constraints on this issue. We carefully selected a sample of quiescent red-sequence galaxies from Sloan Digital Sky Survey. We bin them into three bins with different [N II]/H α and [N II]/[O II] ratios, and we measure the temperature-sensitive [O III] λ4363, [N II] λ5755, [S II] λλ4068, 4076, and [O II] λλ7320, 7330 lines in the stacked spectra. The [S II] doublet ratios indicate the line-emitting gas is in the low-density regime (∼10–200 cm−3). We …

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Characteristics Of Two-Episode Emission Patterns In Fermi Long Gamma-Ray Bursts, Lin Lan, Hou-Jun Lü, Shu-Qing Zhong, Hai-Ming Zhang, Jared Rice, Ji-Gui Cheng, Shen-Shi Du, Long Li, Jie Lin, Rui-Jing Lu, En-Wei Liang Aug 2018

Characteristics Of Two-Episode Emission Patterns In Fermi Long Gamma-Ray Bursts, Lin Lan, Hou-Jun Lü, Shu-Qing Zhong, Hai-Ming Zhang, Jared Rice, Ji-Gui Cheng, Shen-Shi Du, Long Li, Jie Lin, Rui-Jing Lu, En-Wei Liang

Physics & Astronomy Faculty Research

Two-episode emission components separated by quiescent gaps in the prompt emission of gamma-ray bursts (GRBs) have been observed in the Swift era, but there is a lack of spectral information due to the narrow energy band of the Swift/Burst Alert Telescope. In this paper, a systematic analysis of the spectral and temporal properties of the prompt emission of 101 Fermi/Gamma-ray Burst Monitor detected long GRBs show the existence of two-episode emission components in the light curves, with quiescent times of up to hundreds of seconds. We focus on investigating the differences of those two emission episodes. We find that the …

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Polarized Bow Shock Nebulae Reveal Features Of The Winds And Environments Of Massive Stars, Manisha Shrestha Aug 2018

Polarized Bow Shock Nebulae Reveal Features Of The Winds And Environments Of Massive Stars, Manisha Shrestha

Electronic Theses and Dissertations

Massive stars strongly affect their surroundings through their energetic stellar winds during their lifetime and through their energetic deaths as supernovae. When a stellar wind interacts with the local interstellar medium (ISM), if the relative velocity between wind and ISM is supersonic, then a stellar wind bow shock is formed. Bow shocks and related density enhancements produced by the winds of massive stars moving through the interstellar medium provide important information regarding the motions of the stars, the properties of their stellar winds, and the characteristics of the local medium. Since bow shock nebulae are aspherical structures, light scattering within …

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Fluctuating Hydrodynamics Of Reactive Liquid Mixtures, Changho Kim, Andy. Nonaka, John Bell, Alejandro Garcia, Aleksandar Donev Aug 2018

Fluctuating Hydrodynamics Of Reactive Liquid Mixtures, Changho Kim, Andy. Nonaka, John Bell, Alejandro Garcia, Aleksandar Donev

Faculty Publications

Fluctuating hydrodynamics (FHD) provides a framework for modeling microscopic fluctuations in a manner consistent with statistical mechanics and nonequilibrium thermodynamics. This paper presents an FHD formulation for isothermal reactive incompressible liquid mixtures with stochastic chemistry. Fluctuating multispecies mass diffusion is formulated using a Maxwell–Stefan description without assuming a dilute solution, and momentum dynamics is described by a stochastic Navier–Stokes equation for the fluid velocity. We consider a thermodynamically consistent generalization for the law of mass action for non-dilute mixtures and use it in the chemical master equation (CME) to model reactions as a Poisson process. The FHD approach provides remarkable …

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Rossby Vortices In Thin Magnetized Accretion Discs, L. Matilsky, Sergei Dyda, R. V. E. Lovelace, P. S. Lii Aug 2018

Rossby Vortices In Thin Magnetized Accretion Discs, L. Matilsky, Sergei Dyda, R. V. E. Lovelace, P. S. Lii

Physics & Astronomy Faculty Research

We study the Rossby wave instability (RWI) in a thin accretion disc threaded by an initially toroidal magnetic field using the magnetohydrodynamics (MHD) code PLUTO... See full text for full abstract.

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Direct Imaging Of The Hd 35841 Debris Disk: A Polarized Dust Ring From Gemini Planet Imager And An Outer Halo From Hst/Stis, Thomas M. Esposito, Gaspard Duchne, Paul Kalas, Malena Rice, Ilodie Choquet, Bin Ren, Marshall D. Perrin, Christine H. Chen, Pauline Arriaga, Eugene Chiang, Eric L. Nielsen, James R. Graham, Jason J. Wang, Robert J.De Rosa, Katherine B. Follette, S. Mark Ammons, Megan Ansdell, Vanessa P. Bailey, Travis Barman, Juan Sebastián Bruzzone, Joanna Bulger, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Michael P. Fitzgerald, Stephen J. Goodsell, Alexandra Z. Greenbaum, Pascale Hibon, Li Wei Hung, Patrick Ingraham, Quinn Konopacky, James E. Larkin, Kimberly Ward-Duong, Et Al Aug 2018

Direct Imaging Of The Hd 35841 Debris Disk: A Polarized Dust Ring From Gemini Planet Imager And An Outer Halo From Hst/Stis, Thomas M. Esposito, Gaspard Duchne, Paul Kalas, Malena Rice, Ilodie Choquet, Bin Ren, Marshall D. Perrin, Christine H. Chen, Pauline Arriaga, Eugene Chiang, Eric L. Nielsen, James R. Graham, Jason J. Wang, Robert J.De Rosa, Katherine B. Follette, S. Mark Ammons, Megan Ansdell, Vanessa P. Bailey, Travis Barman, Juan Sebastián Bruzzone, Joanna Bulger, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Michael P. Fitzgerald, Stephen J. Goodsell, Alexandra Z. Greenbaum, Pascale Hibon, Li Wei Hung, Patrick Ingraham, Quinn Konopacky, James E. Larkin, Kimberly Ward-Duong, Et Al

Astronomy: Faculty Publications

We present new high resolution imaging of a light-scattering dust ring and halo around the young star HD 35841. Using spectroscopic and polarimetric data from the Gemini Planet Imager in H-band (1.6 μm), we detect the highly inclined (i = 85°) ring of debris down to a projected separation of ∼12 au (∼0.″12) for the first time. Optical imaging from HST/STIS shows a smooth dust halo extending outward from the ring to >140 au (>1.″4). We measure the ring's scattering phase function and polarization fraction over scattering angles of 22°-125°, showing a preference for forward scattering and a polarization …

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Force Multiplier Calculations For X-Ray Binaries And Active Galactic Nuclei, Randall Cody Dannen Aug 2018

Force Multiplier Calculations For X-Ray Binaries And Active Galactic Nuclei, Randall Cody Dannen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Motivated by the work done to explore the winds from hot stars (Lamers & Cassinelli 1999), we develop a method for self consistently calculating force multipliers for Type 1 and Type 2 active galactic nuclei (AGN), soft and hard start X-ray binaries (XRBs) spectral energy distributions (SEDs). We find that the ampflication to the radiation force can be as large as 100 even when the gas is highly ionized due to Fe and O ions. We discuss future efforts to incorporate these findings in magnetohydrodynamic simulations.

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Effect Of Chemistry On Electrodynamics In The Martian Dynamo Region, Morgan M. Matheny Aug 2018

Effect Of Chemistry On Electrodynamics In The Martian Dynamo Region, Morgan M. Matheny

Doctoral Dissertations and Master's Theses

Electromagnetic interactions between Mars remnant crustal magnetic fields and solar and planetary ions lead to time and space variations of the ionosphere. In this work, we continue the investigations started by Riousset et al. [2013] and address the effect of chemistry on ion populations in the dynamo region, where ion dynamics are driven by collisions while electrons are still mostly magnetized. We adopt a mesoscale model to simulate dynamics of electrons and ions in the upper atmosphere (100–400 km). Our approach focuses on numerical studies using the Martian Multifluid Magnetohy drodynamic (MF-MHD) Model (M4). The dynamo is a region which …

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Analysis Of Nucleus Properties Of The Enigmatic Comet 29p/Schwassmann-Wachmann 1, Charles Schambeau Aug 2018

Analysis Of Nucleus Properties Of The Enigmatic Comet 29p/Schwassmann-Wachmann 1, Charles Schambeau

Electronic Theses and Dissertations

We present results from a continuing effort to understand activity drivers for the enigmatic Comet 29P/Schwassmann-Wachmann 1 (SW1). SW1 has been of interest since its discovery almost 100 years ago because of its nearly continuous, quiescent activity beyond the water-sublimation line and its highly variable, outburst activity while receiving a nearly constant insolation due to its low eccentricity orbit. These characteristics make SW1 a useful target for investigating both distant cometary activity drivers and also cometary outburst behavior. We approach answering these questions through a detailed analysis of SW1; first by measuring nucleus properties required for a more accurate nucleus …

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Erratum: The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya Aug 2018

Erratum: The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya

Faculty Publications

This is an erratum to the paper “The SLUGGS Survey: A comparison of total-mass profiles of early-type galaxies from observations and cosmological simulations, to ∼4 effective radii” that was published in 2018, MNRAS, 476, 4543, which we refer to as the original paper.

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Cause Of Cambrian Explosion - Terrestrial Or Cosmic?, Edward J. Steele, Shirwan Al-Mufti, Kenneth A. Augustyn, Rohana Chandrajith, John P. Coghlan, S. G. Coulson, Et. Al. Aug 2018

Cause Of Cambrian Explosion - Terrestrial Or Cosmic?, Edward J. Steele, Shirwan Al-Mufti, Kenneth A. Augustyn, Rohana Chandrajith, John P. Coghlan, S. G. Coulson, Et. Al.

Michigan Tech Publications, Part 1

We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction-diversification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is …

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First Measurement Of Ξ− Polarization In Photoproduction, J. Bono, L. Guo, K. P. Adhikari, M. J. Amaryan, G. Charles, G. Gavalian, M. Khachatryan, A. Klein, Y. Prok, J. Zhang, Z. W. Zhao Aug 2018

First Measurement Of Ξ− Polarization In Photoproduction, J. Bono, L. Guo, K. P. Adhikari, M. J. Amaryan, G. Charles, G. Gavalian, M. Khachatryan, A. Klein, Y. Prok, J. Zhang, Z. W. Zhao

Physics Faculty Publications

Despite decades of studies of the photoproduction of hyperons, both their production mechanisms and their spectra of excited states are still largely unknown. While the parity-violating weak decay of hyperons offers a means of measuring their polarization, which could help discern their production mechanisms and identify their excitation spectra, no such study has been possible for doubly strange baryons in photoproduction, due to low production cross sections. However, by making use of the reaction γ p → K+K+Ξ−, we have measured, for the first time, the induced polarization, P, and the transferred polarization from circularly polarized …

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Strong Evidence For The Density-Wave Theory Of Spiral Structure From A Multi-Wavelength Study Of Disk Galaxies, Hamed Pour-Imani Aug 2018

Strong Evidence For The Density-Wave Theory Of Spiral Structure From A Multi-Wavelength Study Of Disk Galaxies, Hamed Pour-Imani

Graduate Theses and Dissertations

The density-wave theory of spiral structure, though first proposed as long ago as the mid-1960s by C.C. Lin and F. Shu (Lin & Shu, 1964; Bertin & Lin, 1996; Shu, 2016), continues to be challenged by rival theories, such as the manifold theory. One test of these theories which has been proposed is that the pitch angle of spiral arms for galaxies should vary with the wavelength of the image in the density-wave theory, but not in the manifold theory. The reason is that stars are born in the density wave but move out of it as they age. In …

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On Some Metaphysical Problems Of Many Worlds Interpretation Of Quantum Mechanics, Florentin Smarandache, Victor Christianto, Yunita Umniyati Aug 2018

On Some Metaphysical Problems Of Many Worlds Interpretation Of Quantum Mechanics, Florentin Smarandache, Victor Christianto, Yunita Umniyati

Branch Mathematics and Statistics Faculty and Staff Publications

Despite its enormous practical success, many physicists and philosophers alike agree that the quantum theory is full of contradictions and paradoxes which are difficult to solve consistently. Even after 90 years, the experts themselves still do not all agree what to make of it. The area of disagreement centers primarily around the problem of describing observations. Formally, the socalled quantum measurement problem can be defined as follows: the result of a measurement is a superposition of vectors, each representing the quantity being observed as having one of its possible values. The question that has to be answered is : how …

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High Dynamic Range Optical Devices And Applications., Elijah Robert Jensen Aug 2018

High Dynamic Range Optical Devices And Applications., Elijah Robert Jensen

Electronic Theses and Dissertations

Much of what we know about fundamental physical law and the universe derives from observations and measurements using optical methods. The passive use of the electromagnetic spectrum can be the best way of studying physical phenomenon in general with minimal disturbance of the system in the process. While for many applications ambient visible light is sufficient, light outside of the visible range may convey more information. The signals of interest are also often a small fraction of the background, and their changes occur on time scales so quickly that they are visually imperceptible. This thesis reports techniques and technologies developed …

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Collisional Quenching Of Highly Excited H2 Due To H2 Collisions, Yier Wan, B. H. Yang, P. C. Stancil, Balakrishnan Naduvalath, Nikhil J. Parekh, R. C. Forrey Jul 2018

Collisional Quenching Of Highly Excited H2 Due To H2 Collisions, Yier Wan, B. H. Yang, P. C. Stancil, Balakrishnan Naduvalath, Nikhil J. Parekh, R. C. Forrey

Chemistry and Biochemistry Faculty Research

Rate coefficients for pure rotational quenching in H2(ν 1 = 0, j 1) + H2(ν 2 = 0, j 2) collisions from initial levels of j 1 = 2–31 (j 2 = 0 or 1) to all lower rotational levels are presented. We carried out extensive quantum mechanical close-coupling calculations based on a recently published H2–H2 potential energy surface (PES) developed by Patkowski et al. that has been demonstrated to be more reliable than previous work. Rotational transition cross sections with initial levels of j 1 = 2–14, 18, 19, 24, and 25 were computed for energies ranging from 10−6 …

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Gamma-Ray Burst/Supernova Associations: Energy Partition And The Case Of A Magnetar Central Engine, Hon-Jun Lü, Lin Lan, Bing Zhang, En-Wei Liang, David Alexander Kann, Shen-Shi Du, Jun Shen Jul 2018

Gamma-Ray Burst/Supernova Associations: Energy Partition And The Case Of A Magnetar Central Engine, Hon-Jun Lü, Lin Lan, Bing Zhang, En-Wei Liang, David Alexander Kann, Shen-Shi Du, Jun Shen

Physics & Astronomy Faculty Research

The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN) association is the core collapse of massive stars. One possible outcome of such a collapse is a rapidly spinning, strongly magnetized neutron star ("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN associations detected by several instruments before 2017 June. Twenty GRB/SN systems have been confirmed via direct spectroscopic evidence or a clear light curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We derive/collect the basic physical parameters of the GRBs and the SNe, and look for correlations among these parameters. We find that the peak …

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Space-Time In The Syk Model, Sumit R. Das, Aminik Ghosh, Antal Jevicki, Kenta Suzuki Jul 2018

Space-Time In The Syk Model, Sumit R. Das, Aminik Ghosh, Antal Jevicki, Kenta Suzuki

Physics and Astronomy Faculty Publications

We consider the question of identifying the bulk space-time of the SYK model. Focusing on the signature of emergent space-time of the (Euclidean) model, we explain the need for non-local (Radon-type) transformations on external legs of n-point Green’s functions. This results in a dual theory with Euclidean AdS signature with additional legfactors. We speculate that these factors incorporate the coupling of additional bulk states similar to the discrete states of 2d string theory.

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Systematic Mischaracterization Of Exoplanetary System Dynamical Histories From A Model Degeneracy Near Mean-Motion Resonance, John H. Boisvert, Benjamin E. Nelson, Jason H. Steffen Jul 2018

Systematic Mischaracterization Of Exoplanetary System Dynamical Histories From A Model Degeneracy Near Mean-Motion Resonance, John H. Boisvert, Benjamin E. Nelson, Jason H. Steffen

Physics & Astronomy Faculty Research

There is a degeneracy in the radial velocity exoplanet signal between a single planet on an eccentric orbit and a two-planet system with a period ratio of 2:1. This degeneracy could lead to misunderstandings of the dynamical histories of planetary systems as well as measurements of planetary abundances if the correct architecture is not established. We constrain the rate of mischaracterization by analysing a sample of 60 non-transiting, radial velocity systems orbiting main-sequence stars from the NASA Exoplanet Archive (NASA Archive) using a new Bayesian model comparison pipeline. We find that 15 systems (25 per cent of our sample) show …

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Globular Cluster Population Of The Hst Frontier Fields Galaxy J07173724+3744224, Nathan L. Carlson, Madina R. Sultanova, Sandanuwan P. Kalawila Vithanage, Wayne A. Barkhouse, Gihan L. Ipita Kaduwa Gamage, Cody M. Rude, Omar López-Cruz Jul 2018

Globular Cluster Population Of The Hst Frontier Fields Galaxy J07173724+3744224, Nathan L. Carlson, Madina R. Sultanova, Sandanuwan P. Kalawila Vithanage, Wayne A. Barkhouse, Gihan L. Ipita Kaduwa Gamage, Cody M. Rude, Omar López-Cruz

Physics Faculty Publications

We present the first measurement of the globular cluster (GC) population surrounding the elliptical galaxy J07173724+3744224 (⁠z" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative;">zz = 0.1546). This galaxy is located in the foreground in the field-of-view of the Hubble Space Telescope (HST) Frontier Fields observations of galaxy cluster MACS J0717.5+3745 (⁠z" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: …

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Asymmetric Free-Space Light Transport At Nonlinear Metasurfaces, Nir Shitrit, Jeongmin Kim, David S. Barth, Hamidreza Ramezani, Yuan Wang, Xiang Zhang Jul 2018

Asymmetric Free-Space Light Transport At Nonlinear Metasurfaces, Nir Shitrit, Jeongmin Kim, David S. Barth, Hamidreza Ramezani, Yuan Wang, Xiang Zhang

Physics & Astronomy Faculty Publications

Asymmetric light transport has significantly contributed to fundamental science and revolutionized advanced technology in various aspects such as unidirectional photonic devices, optical diodes, and isolators. While metasurfaces mold wave fronts at will with an ultrathin flat optical element, asymmetric transport of light cannot be fundamentally achieved by any linear system including linear metasurfaces. We report asymmetric transport of free-space light at nonlinear metasurfaces upon transmission and reflection. Moreover, we theoretically derive the nonlinear generalized Snell's laws that were experimentally confirmed by the anomalous nonlinear refraction and reflection. The asymmetric transport at optically thin nonlinear interfaces is revealed by the concept …

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Surf: Understanding And Predicting Urban Convection And Haze, X. Liang, S. Miao, J. Li, R. Bornstein, X. Zhang, Y. Gao, F. Chen, X. Cao, Z. Cheng, Craig Clements, W. Dabberdt, A. Ding, D. Ding, J. J. Dou, J.X. Dou, Y. Dou, C.S.B. Grimmond, J. E. González-Cruz, J. He, M. Huang, X. Huang, S. Ju, Q. Li, D. Niyogi, J. Quan, J. Sun, J.Z. Sun, M. Yu, J. Zhang, Y. Zhang, X. Zhao, Z. Zheng, M. Zhou Jul 2018

Surf: Understanding And Predicting Urban Convection And Haze, X. Liang, S. Miao, J. Li, R. Bornstein, X. Zhang, Y. Gao, F. Chen, X. Cao, Z. Cheng, Craig Clements, W. Dabberdt, A. Ding, D. Ding, J. J. Dou, J.X. Dou, Y. Dou, C.S.B. Grimmond, J. E. González-Cruz, J. He, M. Huang, X. Huang, S. Ju, Q. Li, D. Niyogi, J. Quan, J. Sun, J.Z. Sun, M. Yu, J. Zhang, Y. Zhang, X. Zhao, Z. Zheng, M. Zhou

Faculty Publications, Meteorology and Climate Science

Urbanization modifies atmospheric energy and moisture balances, forming distinct features [e.g., urban heat islands (UHIs) and enhanced or decreased precipitation]. These produce significant challenges to science and society, including rapid and intense flooding, heat waves strengthened by UHIs, and air pollutant haze. The Study of Urban Impacts on Rainfall and Fog/Haze (SURF) has brought together international expertise on observations and modeling, meteorology and atmospheric chemistry, and research and operational forecasting. The SURF overall science objective is a better understanding of urban, terrain, convection, and aerosol interactions for improved forecast accuracy. Specific objectives include a) promoting cooperative international research to improve …

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