Open Access. Powered by Scholars. Published by Universities.®

Astrophysics and Astronomy Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 2281 - 2310 of 8856

Full-Text Articles in Astrophysics and Astronomy

Quantum Correlations Between The Light And Kilogram-Mass Mirrors Of Ligo, Haocun Yu, L. Mcmuller, M. Tse, L. Barsotti, N. Mavalvala, J. Betzwieser, C. D. Blair, S. E. Dwyer, A. Effler, K. E. Ramirez Jan 2020

Quantum Correlations Between The Light And Kilogram-Mass Mirrors Of Ligo, Haocun Yu, L. Mcmuller, M. Tse, L. Barsotti, N. Mavalvala, J. Betzwieser, C. D. Blair, S. E. Dwyer, A. Effler, K. E. Ramirez

Physics & Astronomy Faculty Publications

Measurement of minuscule forces and displacements with ever greater precision encounters a limit imposed by a pillar of quantum mechanics: the Heisenberg uncertainty principle. A limit to the precision with which the position of an object can be measured continuously is known as the standard quantum limit (SQL) [1–4]. When light is used as the probe, the SQL arises from the balance between the uncertainties of photon radiation pressure imposed on the object and of the photon number in the photoelectric detection. The only possibility surpassing the SQL is via correlations within the position/momentum uncertainty of the object and the …


Identifying Active Kelvin–Helmholtz Vortices On Saturn's Magnetopause Boundary, B. L. Burkholder, P. A. Delamere, Jay R. Johnson, C.- S. Ng Jan 2020

Identifying Active Kelvin–Helmholtz Vortices On Saturn's Magnetopause Boundary, B. L. Burkholder, P. A. Delamere, Jay R. Johnson, C.- S. Ng

Faculty Publications

For Cassini magnetopause encounters, we analyse plasma and magnetic fields. The boundary can be unstable to the Kelvin–Helmholtz instability (KHI), which can drive large‐scale flows identifiable in plasma measurements. Bulk flow reversed from the expected direction near the magnetopause can indicate vorticity associated with active KH, and events are found dominantly in the dawn–subsolar region. KHIs are also responsible for magnetic field fluctuations, and hybrid simulations indicate heating, and transport is significant in an actively growing vortex. Cassini observations are filtered for disturbed magnetic fields near the magnetopause, similar to the signatures from hybrid simulations, with significant fluctuation and current …


Historical Milestones In Astronomy: As Shown Through The Byu Special Collections Archives, Dan Broadbent Jan 2020

Historical Milestones In Astronomy: As Shown Through The Byu Special Collections Archives, Dan Broadbent

Faculty Publications

Science Research: The “Long Conversation”

  • Ideas in science can take a long time to develop.
  • How do they develop?
  • These books document a part of a conversation that began 447 years ago and spanned a 153 year period… documenting:
  • how the overall nature of the universe was worked out,
  • the establishment of the scientific method, and the boundaries of religious authority,
  • and culminated in Isaac Newton’s book that presented his three laws of motion that allow us to explore the universe to this day.


Gw190412: Observation Of A Binary-Black-Hole Coalescence With Asymmetric Masses, R. Abbott, T. D. Abbott, S. Abraham, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, P. K. Roy Jan 2020

Gw190412: Observation Of A Binary-Black-Hole Coalescence With Asymmetric Masses, R. Abbott, T. D. Abbott, S. Abraham, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, P. K. Roy

Physics & Astronomy Faculty Publications

We report the observation of gravitational waves from a binary-black-hole coalescence during the first two weeks of LIGO’s and Virgo’s third observing run. The signal was recorded on April 12, 2019 at 05∶30∶44 UTC with a network signal-to-noise ratio of 19. The binary is different from observations during the first two observing runs most notably due to its asymmetric masses: a ∼30 M⊙ black hole merged with a ∼8 M⊙ black hole companion. The more massive black hole rotated with a dimensionless spin magnitude between 0.22 and 0.60 (90% probability). Asymmetric systems are predicted to emit gravitational waves with stronger …


A Simple Graphical Method For Calculating The Standing Wave Frequencies On A Rectangular Membrane, Joseph D. Romano, Richard H. Price Jan 2020

A Simple Graphical Method For Calculating The Standing Wave Frequencies On A Rectangular Membrane, Joseph D. Romano, Richard H. Price

Physics & Astronomy Faculty Publications

In introductory physics courses, simple arguments based on traveling waves on a string are used to relate the frequency of standing waves to boundary conditions, e.g., the fixed ends of the string. Here, we extend that approach to two-dimensional waves such as the oscillations of a rectangular membrane with edges fixed at the boundary. This results in a graphical method that uses only simple geometry and is suitable for explaining two-dimensional standing-wave oscillations to non-science majors, e.g., in a physics of sound and music class.


A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, Matt Wentzel-Long Jan 2020

A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, Matt Wentzel-Long

Doctoral Dissertations

”The W4 HII region is home to a large number of O and B-type stars as well as the young open cluster IC 1805. OB-type produce intense photoionizing radiation and stellar winds that can induce star formation in surrounding molecular clouds and sometimes carve out large regions of decreased particle density called superbubbles. During the star- formation process, young stellar objects (YSOs) are initially surrounded by circumstellar disks made of gas and dust which naturally dissipate after several million years. The dissipation of the disk is thought to occur for a variety of reasons, including photoevaporation by the encompassed protostar …


Long-Range Electroweak Amplitudes Of Single Hadrons From Euclidean Finite-Volume Correlation Functions, Raúl A. Briceño, Zohreh Davoudi, Maxwell T. Hansen, Matthias R. Schindler, Alessandro Baroni Jan 2020

Long-Range Electroweak Amplitudes Of Single Hadrons From Euclidean Finite-Volume Correlation Functions, Raúl A. Briceño, Zohreh Davoudi, Maxwell T. Hansen, Matthias R. Schindler, Alessandro Baroni

Physics Faculty Publications

A relation is presented between single-hadron long-range matrix elements defined in a finite Euclidean spacetime and the corresponding infinite-volume Minkowski amplitudes. This relation is valid in the kinematic region where any number of two-hadron states can simultaneously go on shell, so that the effects of strongly coupled intermediate channels are included. These channels can consist of nonidentical particles with arbitrary intrinsic spins. The result accommodates general Lorentz structures as well as nonzero momentum transfer for the two external currents inserted between the single-hadron states. The formalism, therefore, generalizes the work by Christ et al. [Phys. Rev. D 91, 114510 …


Beyond Equilibrium Temperature: How The Atmosphere/Interior Connection Affects The Onset Of Methane, Ammonia, And Clouds In Warm Transiting Giant Planets, Jonathan J. Fortney, Channon Visscher, Mark S. Marley, Callie E. Hood, Michael R. Line, Daniel P. Thorngren, Richard S. Freedman, Roxana Lupu Jan 2020

Beyond Equilibrium Temperature: How The Atmosphere/Interior Connection Affects The Onset Of Methane, Ammonia, And Clouds In Warm Transiting Giant Planets, Jonathan J. Fortney, Channon Visscher, Mark S. Marley, Callie E. Hood, Michael R. Line, Daniel P. Thorngren, Richard S. Freedman, Roxana Lupu

Faculty Work Comprehensive List

The atmospheric pressure–temperature profiles for transiting giant planets cross a range of chemical transitions. Here we show that the particular shapes of these irradiated profiles for warm giant planets below ∼1300 K lead to striking differences in the behavior of nonequilibrium chemistry compared to brown dwarfs of similar temperatures. Our particular focus is H2O, CO, CH4, CO2, and NH3 in Jupiter- and Neptune-class planets. We show that the cooling history of a planet, which depends most significantly on planetary mass and age, can have a dominant effect on abundances in the visible atmosphere, often swamping trends one might expect based …


Extreme Ultraviolet Quasar Colours From Galex Observations Of The Sdss Dr14q Catalogue, Daniel E. Vanden Berk, Sarah C. Wesolowski, Mary J. Yeckley, Joseph M. Marcinik, Jean M. Quashnock, Lawrence M. Machia, Jian Wu Jan 2020

Extreme Ultraviolet Quasar Colours From Galex Observations Of The Sdss Dr14q Catalogue, Daniel E. Vanden Berk, Sarah C. Wesolowski, Mary J. Yeckley, Joseph M. Marcinik, Jean M. Quashnock, Lawrence M. Machia, Jian Wu

Computer Science Faculty Publications

The rest-frame far to extreme ultraviolet (UV) colour–redshift relationship has been constructed from data on over 480,000 quasars carefully cross-matched between SDSS Data Release 14 and the final GALEX photometric catalogue. UV matching and detection probabilities are given for all the quasars, including dependencies on separation, optical brightness, and redshift. Detection limits are also provided for all objects. The UV colour distributions are skewed redward at virtually all redshifts, especially when detection limits are accounted for. The median GALEX far-UV minus near-UV (FUV − NUV) colour–redshift relation is reliably determined up to z ≈ 2.8, corresponding to rest-frame wavelengths as …


Astro2020 Apc White Paper. 2020 Vision: Towards A Sustainable Oir System, Sally Oey, Terry D. Oswalt, Tom Maccarone, Fred Walter, Charles Bailyn, Jay Gallagher, Todd Henry, Derek Buzasi, J. Allyn Smith, Rachael Beaton, Jim Webb, Brad Barlow, Misty Bentz, Leslie Hebb, Patrick Kelly, Jedidah Isler, Michael Meyer, John Salzer, Simone Scaringi Jan 2020

Astro2020 Apc White Paper. 2020 Vision: Towards A Sustainable Oir System, Sally Oey, Terry D. Oswalt, Tom Maccarone, Fred Walter, Charles Bailyn, Jay Gallagher, Todd Henry, Derek Buzasi, J. Allyn Smith, Rachael Beaton, Jim Webb, Brad Barlow, Misty Bentz, Leslie Hebb, Patrick Kelly, Jedidah Isler, Michael Meyer, John Salzer, Simone Scaringi

Publications

Open-access telescopes of all apertures are needed to operate a competitive and efficient national science program. While larger facilities contribute light-gathering power and angular resolution, smaller ones dominate for field of view, time-resolution, and especially, total available observing time, thereby enabling our entire, diversely-expert community. Smaller aperture telescopes therefore play a critical and indispensable role in advancing science. Thus, the divestment of NSF support for modest-aperture (1 – 4 m) public telescopes poses a serious threat to U.S. scientific leadership, which is compounded by the unknown consequences of the shift from observations driven by individual investigators to survey-driven science. Given …


Aspects Of Quantum Theory In General Relativity And Cosmology, Eamon Mccaughey Jan 2020

Aspects Of Quantum Theory In General Relativity And Cosmology, Eamon Mccaughey

Doctoral

After a brief introduction to Cosmology some quantum aspects of General Relativity and cosmology are presented. The radial motion of a massive particles in the ergosphere of the Kerr Black Hole is considered. Screening of Hawking radiation and shielding of the Penrose process is examined in the context of the region of negative energy inside the ergosphere. Tunnelling of such particles between the boundaries of the classically forbidden region will be considered and the transmission coefficient determined. The evolution of Primordial black holes in standard and Loop Quantum Cosmology is reviewed. A stability analysis of Einstein’s universe in both classical …


Cosmic-Ray Acceleration In The Cygnus Ob2 Stellar Association, Binita Hona Jan 2020

Cosmic-Ray Acceleration In The Cygnus Ob2 Stellar Association, Binita Hona

Dissertations, Master's Theses and Master's Reports

The Cygnus region of our Galaxy consists of an active star forming region and a wealth of various astrophysical sources such as pulsar wind nebulae (PWN), supernova remnants (SNRs), and massive star clusters. Massive stellar clusters and associations have been postulated as possible sources of cosmic rays (CRs) in our Galaxy. One example of a gamma-ray source associated with a stellar association lies in the Cygnus region known as the "Cygnus Cocoon". It is an extended region of gamma-ray emission in the Cygnus X region and attributed to a possible superbubble with freshly accelerated CRs which are hypothesized to produce …


A Guide To Ligo–Virgo Detector Noise And Extraction Of Transient Gravitational-Wave Signals, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration Jan 2020

A Guide To Ligo–Virgo Detector Noise And Extraction Of Transient Gravitational-Wave Signals, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellarmass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitationalwave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data …


A Guide To Ligo–Virgo Detector Noise And Extraction Of Transient Gravitational-Wave Signals, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, W. H. Wang, A. K. Zadrozny Jan 2020

A Guide To Ligo–Virgo Detector Noise And Extraction Of Transient Gravitational-Wave Signals, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, W. H. Wang, A. K. Zadrozny

Physics & Astronomy Faculty Publications

The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellar-mass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitational-wave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data …


Electrochemically Desulfurized Molybdenum Disulfide (Mos2) And Reduced Graphene Oxide Aerogel Composites As Efficient Electrocatalysts For Hydrogen Evolution, Sanju Gupta, Taylor Robinson, Nicholas Dimakis Jan 2020

Electrochemically Desulfurized Molybdenum Disulfide (Mos2) And Reduced Graphene Oxide Aerogel Composites As Efficient Electrocatalysts For Hydrogen Evolution, Sanju Gupta, Taylor Robinson, Nicholas Dimakis

Physics & Astronomy Faculty Publications

Recent developments in graphene related materials including molybdenum disulfide (MoS2) is gaining popularity as efficient and cost-effective nanoscale electrocatalyst essential for hydrogen production. These “clean” energy technologies require delicate control over geometric, morphological, chemical and electronic structure affecting physical and electrochemical catalytic properties. In this work, we prepared three-dimensional hierarchical mesoporous aerogels consisting of two-dimensional functionalized graphene and MoS2 nanosheets of varying ratio of components under hydrothermal–solvothermal conditions (P bar, T °C). We systematically characterized these hybrid aerogels in terms of surface morphology, microstructure, understand heterointerfaces interaction through electron microscopy, X-ray diffraction, optical absorption and emission …


A Joint Fermi-Gbm And Ligo/Virgo Analysis Of Compact Binary Mergers From The First And Second Gravitational-Wave Observing Runs, R. Hamburg, C. Fletcher, E. Burns, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Wenhui Wang, Adam Zadrozny Jan 2020

A Joint Fermi-Gbm And Ligo/Virgo Analysis Of Compact Binary Mergers From The First And Second Gravitational-Wave Observing Runs, R. Hamburg, C. Fletcher, E. Burns, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Wenhui Wang, Adam Zadrozny

Physics & Astronomy Faculty Publications

We present results from offline searches of Fermi Gamma-ray Burst Monitor (GBM) data for gamma-ray transients coincident with the compact binary coalescences observed by the gravitational-wave (GW) detectors Advanced LIGO and Advanced Virgo during their first and second observing runs. In particular, we perform follow-up for both confirmed events and low significance candidates reported in the LIGO/Virgo catalog GWTC-1. We search for temporal coincidences between these GW signals and GBM-triggered gamma-ray bursts (GRBs). We also use the GBM Untargeted and Targeted subthreshold searches to find coincident gamma-rays below the onboard triggering threshold. This work implements a refined statistical approach by …


Wallaby – An Ska Pathfinder Hisurvey, B. S. Koribalski, L. Stavely-Smith, Tobias Westmeier, P. Serra, K. Spekkens, O. I. Wang, C. D. P. Lagos, D. Obreschkow, E. V. Ryan-Webber, Juan P. Madrid Jan 2020

Wallaby – An Ska Pathfinder Hisurvey, B. S. Koribalski, L. Stavely-Smith, Tobias Westmeier, P. Serra, K. Spekkens, O. I. Wang, C. D. P. Lagos, D. Obreschkow, E. V. Ryan-Webber, Juan P. Madrid

Physics & Astronomy Faculty Publications

The Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) is a next-generation survey of neutral hydrogen (HI) in the Local Universe. It uses the widefield, high-resolution capability of the Australian Square Kilometer Array Pathfinder (ASKAP), a radio interferometer consisting of 36 x 12-m dishes equipped with Phased-Array Feeds (PAFs), located in an extremely radio-quiet zone in Western Australia. WALLABY aims to survey three-quarters of the sky (-90 degr < Dec < +30 degr) to a redshift of z < 0.26, and generate spectral line image cubes at ~30 arcsec resolution and ~1.6 mJy/beam per 4 km/s channel sensitivity. ASKAP's instantaneous field of view at 1.4 GHz, delivered by the PAF's 36 beams, is about 30 sq deg. At an integrated signal-to-noise ratio of five, WALLABY is expected to detect over half a million galaxies with a mean redshift of z ~ 0.05 (~200 Mpc). The scientific goals of WALLABY include: (a) a census of gas-rich galaxies in the vicinity of the Local Group; (b) a study of the HI properties of galaxies, groups and clusters, in particular the influence of the environment on galaxy evolution; and (c) the refinement of cosmological parameters using the spatial and redshift distribution of low-bias gas-rich galaxies. For context we provide an overview of previous large-scale HI surveys. Combined with existing and new multi-wavelength sky surveys, WALLABY will enable an exciting new generation of panchromatic studies of the Local Universe. - First results from the WALLABY pilot survey are revealed, with initial data products publicly available in the CSIRO ASKAP Science Data Archive (CASDA).


Gw190814: Gravitational Waves From The Coalescence Of A 23 Solar Mass Black Hole With A 2.6 Solar Mass Compact Object, R. Abbott, T. D. Abbott, S. Abraham, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Soma Mukherjee Jan 2020

Gw190814: Gravitational Waves From The Coalescence Of A 23 Solar Mass Black Hole With A 2.6 Solar Mass Compact Object, R. Abbott, T. D. Abbott, S. Abraham, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Soma Mukherjee

Physics & Astronomy Faculty Publications

We report the observation of a compact binary coalescence involving a 22.2 - 24.3 M⊙ black hole and a compact object with a mass of 2.50 - 2.67 M⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO's and Virgo's third observing run on August 14, 2019 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of 241+41−45 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with …


Nature Inspired Solid–Liquid Phase Amphibious Adhesive, Alin Cristian Chipara, Gustavo Brunetto, Sehmus Ozden, Henrik Haspel, Partha Kumbhakar, Ákos Kukovecz, Zoltán Kónya, Robert Vajtai, Mircea Chipara, Douglas S. Galvao Jan 2020

Nature Inspired Solid–Liquid Phase Amphibious Adhesive, Alin Cristian Chipara, Gustavo Brunetto, Sehmus Ozden, Henrik Haspel, Partha Kumbhakar, Ákos Kukovecz, Zoltán Kónya, Robert Vajtai, Mircea Chipara, Douglas S. Galvao

Physics & Astronomy Faculty Publications

Here we report a new class of bio-inspired solid–liquid adhesive, obtained by simple mechanical dispersion of PVDF (polyvinylidene fluoride) (solid spheres) into PDMS (polydimethylsiloxane) (liquid). The adhesive behavior arises from strong solid–liquid interactions. This is a chemical reaction free adhesive (no curing time) that can be repeatedly used and is capable of instantaneously joining a large number of diverse materials (metals, ceramic, and polymer) in air and underwater. The current work is a significant advance in the development of amphibious multifunctional adhesives and presents potential applications in a range of sealing applications, including medical ones.


Constant Intensity Conical Diffraction In Discrete One-Dimensional Lattices With Charge-Conjugation Symmetry, Mojgan Dehghani, Cem Yuce, Tsampikos Kottos, Hamidreza Ramezani Jan 2020

Constant Intensity Conical Diffraction In Discrete One-Dimensional Lattices With Charge-Conjugation Symmetry, Mojgan Dehghani, Cem Yuce, Tsampikos Kottos, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We engineer anomalous conical diffraction (CD), occurring in discrete one-dimensional lattices with chargeconjugation symmetry when an exceptional point is in the proximity of the modes that compose the initial excitation. The evolving waveform propagates ballistically, acquiring a constant intensity profile within the boundaries of the spreading cone. The linear increase in the total intensity along the propagation direction is responsible for the generation of constant intensity CD.


Investigation Of Small-Scale Energy Release And Transfer Processes In The Solar Atmosphere With High-Resolution Observations In Infrared, Xu Yang Dec 2019

Investigation Of Small-Scale Energy Release And Transfer Processes In The Solar Atmosphere With High-Resolution Observations In Infrared, Xu Yang

Dissertations

Solar spectrum in the infrared (IR) contains abundant information of solar activities, however, it has not spectral lines in the solar IR spectrum provide different tools to probe the solar atmosphere in various heights. This radiation band in such relatively long wavelength includes various atom and molecule spectral lines that are generated by relatively small energy level transitions. The temperature-sensitive and highly dynamic spectral lines could reveal the energy transmission process more easily than those in the visible wavelength of solar emission. Moreover, the better magnetic sensitivities for the infrared lines resulting from their longer wavelength make them detect the …


Investigation Of Membrane Protein Dynamics Using Correlative Single-Particle Tracking And Super-Resolution Microscopy Combined With Bayesian Inference Of Diusion In Arbitrary Landscapes, Hanieh Mazloom Farsibaf Dec 2019

Investigation Of Membrane Protein Dynamics Using Correlative Single-Particle Tracking And Super-Resolution Microscopy Combined With Bayesian Inference Of Diusion In Arbitrary Landscapes, Hanieh Mazloom Farsibaf

Physics & Astronomy ETDs

Many experiments have shown that the diffusive motion of lipids and membrane proteins are slower on the cell surface than those in artificial lipid bilayers or blebs. One hypothesis that may partially explain this mystery is the effect of the cytoskeleton structures on the protein dynamics. To test this hypothesis, we designed a high-speed single particle tracking microscope and use a hybrid tracking and super-resolution approach on the same cell. We labeled the high-affinity FceRI receptor as a transmembrane protein and GPI-anchored proteins as an example of outer leaflet protein in Rat Basophilic Leukemia (RBL) cells and tracked these membrane …


The Timing Of Dynamical Interactions Between Planets In Exoplanetary Systems, David Robert Rice Dec 2019

The Timing Of Dynamical Interactions Between Planets In Exoplanetary Systems, David Robert Rice

UNLV Theses, Dissertations, Professional Papers, and Capstones

During the late stage of planet formation, a system is often dynamically packed with protoplanets. These bodies collide together and are ejected from the system to form the final planets. The duration of stability before these dynamical interactions occur is dependent on the initial separation of the bodies in a system. Previous works have shown that the time before a planet-planet close encounter is exponential with the initial planet spacing measured in units of mutual Hill radius. We investigate the limitations of these previous studies. We find that systems that are initially similar can have larger differences in stability times …


Direct Observation Of Atomic Exchange During Surface Self-Diffusion, Matthew Aaron Koppa Dec 2019

Direct Observation Of Atomic Exchange During Surface Self-Diffusion, Matthew Aaron Koppa

Physics & Astronomy ETDs

The diffusion of adatoms across the (100) plane of iridium has been previously inferred to occur by an exchange mechanism based on site mapping. This study provides the first direct observation that surface self-diffusion can occur by exchange. Iridium enriched to ≥93% 191Ir was deposited onto an atomically clean and smooth Ir(100) plane as observed in an atom probe field ion microscope. Following thermally activated surface self-diffusion the adatom was field desorbed and mass analyzed. Observation of the 193Ir isotope in one-half of the cases demonstrates conclusively that atomic exchange can occur during surface self-diffusion.


The Distribution Of Ultra-Diffuse And Ultra-Compact Galaxies In The Frontier Fields, Steven Janssens, Roberto Abraham, Jean Brodie, Duncan Forbes, Aaron Romanowsky Dec 2019

The Distribution Of Ultra-Diffuse And Ultra-Compact Galaxies In The Frontier Fields, Steven Janssens, Roberto Abraham, Jean Brodie, Duncan Forbes, Aaron Romanowsky

Faculty Publications

Large low-surface-brightness galaxies have recently been found to be abundant in nearby galaxy clusters. In this paper, we investigate these ultra-diffuse galaxies (UDGs) in the six Hubble Frontier Fields galaxy clusters: A2744, MACS J0416.1−2403, MACS J0717.5+3745, MACS J1149.5+2223, AS1063, and A370. These are the most massive (1–3 × 1015 M ⊙) and distant (0.308 < z < 0.545) systems in which this class of galaxy has yet been discovered. We estimate that the clusters host of the order of ~200–1400 UDGs inside the virial radius (R 200), consistent with the UDG abundance–halo-mass relation found in the local universe, and suggest that UDGs may be formed in clusters. Within each cluster, however, we find that UDGs are not evenly distributed. Instead their projected spatial distributions are lopsided, and they are deficient in the regions of highest mass density as traced by gravitational lensing. While the deficiency of UDGs in central regions is not surprising, the lopsidedness is puzzling. The UDGs, and their lopsided spatial distributions, may be associated with known substructures late in their infall into the clusters, meaning that we find evidence both for formation of UDGs in clusters and for UDGs falling into clusters. We also investigate the ultra-compact dwarfs (UCDs) residing in the clusters, and find that the spatial distributions of UDGs and UCDs appear anticorrelated. Around 15% of UDGs exhibit either compact nuclei or nearby point sources. Taken together, these observations provide additional evidence for a picture in which at least some UDGs are destroyed in dense cluster environments and leave behind a residue of UCDs.


Stellar Chromospheric Activity And Age Relation From Open Clusters In The Lamost Survey, Jiajun Zhang, Terry Oswalt, Jingkun Zhao, Xiangsong Fang, Gang Zhao, Xilong Liang, Xianhao Ye, Jing Zhong Dec 2019

Stellar Chromospheric Activity And Age Relation From Open Clusters In The Lamost Survey, Jiajun Zhang, Terry Oswalt, Jingkun Zhao, Xiangsong Fang, Gang Zhao, Xilong Liang, Xianhao Ye, Jing Zhong

Publications

No abstract provided.


Bayesian Characterization Of Main-Sequence Binaries In The Old Open Cluster Ngc 188, Roger E. Cohen, Ted Von Hippel, Aaron M. Geller Dec 2019

Bayesian Characterization Of Main-Sequence Binaries In The Old Open Cluster Ngc 188, Roger E. Cohen, Ted Von Hippel, Aaron M. Geller

Publications

The binary fractions of open and globular clusters yield powerful constraints on their dynamical state and evolutionary history. We apply publicly available Bayesian analysis tools to a UBV RIJHKS photometric catalog of the open cluster NGC 188 to detect and characterize photometric binaries along the cluster main sequence. This technique has the advantage of self-consistently handling photometric errors, missing data in various bandpasses, and star-by-star prior constraints on cluster membership. Simulations are used to verify uncertainties and quantify selection biases in our analysis, illustrating that among binaries with mass ratios >0.5, we recover the binary fraction to better than …


Precise Mass Determination Of Spt-Cl J2106-5844, The Most Massive Cluster At Z > 1, Jinhyub Kim, M. James Jee, Saul Perlmutter, Brian Hayden, David Rubin, Xiaosheng Huang, Greg Aldering, Jongwan Ko Dec 2019

Precise Mass Determination Of Spt-Cl J2106-5844, The Most Massive Cluster At Z > 1, Jinhyub Kim, M. James Jee, Saul Perlmutter, Brian Hayden, David Rubin, Xiaosheng Huang, Greg Aldering, Jongwan Ko

Physics and Astronomy

We present a detailed high-resolution weak-lensing study of SPT-CL J2106-5844 at z = 1.132, claimed to be the most massive system discovered at z > 1 in the South Pole Telescope Sunyaev–Zel'dovich survey. Based on the deep imaging data from the Advanced Camera for Surveys and Wide Field Camera 3 on board the Hubble Space Telescope, we find that the cluster mass distribution is asymmetric, composed of a main clump and a subclump ~640 kpc west thereof. The central clump is further resolved into two smaller northwestern and southeastern substructures separated by ~150 kpc. We show that this rather complex …


Transmission Spectroscopy Of Wasp-79b From 0.6 To 5.0 Μm, Kristin S. Sotzen, Kevin B. Stevenson, David K. Sing, Brian M. Kilpatrick, Hannah R. Wakeford, Joseph C. Filippazzo, Nikole K. Lewis, Sarah M. Hörst, Mercedes López-Morales, Gregory W. Henry, Lars A. Buchhave, David Ehrenreich, Jonathan D. Fraine, Antonio García Muñoz, Rahul Jayaraman, Panayotis Lavvas, Alain Lecavelier Des Etangs, Mark S. Marley, Nikolay Nikolov, Alexander D. Rathcke, Jorge Sanz-Forcada Dec 2019

Transmission Spectroscopy Of Wasp-79b From 0.6 To 5.0 Μm, Kristin S. Sotzen, Kevin B. Stevenson, David K. Sing, Brian M. Kilpatrick, Hannah R. Wakeford, Joseph C. Filippazzo, Nikole K. Lewis, Sarah M. Hörst, Mercedes López-Morales, Gregory W. Henry, Lars A. Buchhave, David Ehrenreich, Jonathan D. Fraine, Antonio García Muñoz, Rahul Jayaraman, Panayotis Lavvas, Alain Lecavelier Des Etangs, Mark S. Marley, Nikolay Nikolov, Alexander D. Rathcke, Jorge Sanz-Forcada

Information Systems and Engineering Management Research Publications

As part of the Panchromatic Exoplanet Treasury program, we have conducted a spectroscopic study of WASP-79b, an inflated hot Jupiter orbiting an F-type star in Eridanus with a period of 3.66 days. Building on the original WASP and TRAPPIST photometry of Smalley et al., we examine Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) (1.125–1.650 μm), Magellan/Low Dispersion Survey Spectrograph (LDSS)-3C (0.6–1 μm) data, and Spitzer data (3.6 and 4.5 μm). Using data from all three instruments, we constrain the water abundance to be −2.20 ≤ log(H2O) ≤ −1.55. We present these results along with the results of an atmospheric …


Dark Matter Production Beyond The Thermal Wimp Paradigm: An Exploration Of Early Matter Domination Scenarios, Jacek Ksawery Osinski Dec 2019

Dark Matter Production Beyond The Thermal Wimp Paradigm: An Exploration Of Early Matter Domination Scenarios, Jacek Ksawery Osinski

Physics & Astronomy ETDs

In the standard thermal history of the Universe, the energy density is dominated by radiation throughout the postinflationary era, until matter-radiation equality after big bang nucleosynthesis (BBN). However, we currently do not have any observational probes of the pre-BBN period, and radiation domination (RD) is therefore an assumption. Generic early Universe models predict the presence of additional components in the postinflationary Universe which can lead to periods of nonstandard evolution before the onset of BBN. A prominent example of such a period is a phase of early matter domination (EMD) in which the Universe undergoes matter-dominated expansion for a time, …