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2017

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Articles 31 - 60 of 395

Full-Text Articles in Astrophysics and Astronomy

Exterior Giant Planet Effects On Terrestrial Architecture, Anna Corinne Childs Dec 2017

Exterior Giant Planet Effects On Terrestrial Architecture, Anna Corinne Childs

UNLV Theses, Dissertations, Professional Papers, and Capstones

Terrestrial planet formation is a chaotic and violent process which is not fully understood. Prior to Kepler, Solar System observations were the basis for planet formation models. How- ever, Kepler observations have shown that exoplanet systems are very different from our solar system, thus requiring a more complete planet formation model. With advancements in com- putational ability, N-body integrators, and collision models, we can explore planet formation by experimenting with simulations in different parameter space. Our Solar System has shown us that exterior giant planets can play a vital role in the shaping of the final terrestrial planet system. Our …

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Using Two Simulation Tools To Teach Concepts In Introductory Astronomy: A Design-Based Research Approach, Pamela A. Maher Dec 2017

Using Two Simulation Tools To Teach Concepts In Introductory Astronomy: A Design-Based Research Approach, Pamela A. Maher

UNLV Theses, Dissertations, Professional Papers, and Capstones

Technology in college classrooms has gone from being an enhancement to the learning experience to being something expected by both instructors and students. This design-based research investigation takes technology one step further, putting the tools used to teach directly in the hands of students. The study examined the affordances and constraints of two simulation tools for use in introductory astronomy courses. The variety of experiences participants had using two tools; a virtual reality headset and fulldome immersive planetarium simulation, to manipulate a lunar surface flyby were identified using a multi-method research approach with N = 67 participants. Participants were recruited …

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Probing Broad Line Regions Of Active Galactic Nuclei, Champika Sandamali Weerasooriya Dec 2017

Probing Broad Line Regions Of Active Galactic Nuclei, Champika Sandamali Weerasooriya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The broad line regions (BLR) of Type I Active galactic nuclei (AGN) are too small to be spatially resolved even with the most powerful telescopes available. Observations suggest that BLR gas is moving under the influence of the gravitational potential of the central supermassive black-hole (SMBH) and responds to the variations in the ionizing continuum flux of the accretion disk, giving rise to broad emission line variations with a time delay. Reverberation mapping campaigns seek to use this time variability to resolve the BLRs in the time domain instead of spatial domain, providing a way to infer geometry and kinematics …

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On The Progenitor Of Binary Neutron Star Merger Gw170817, B. P. Abbott, K. Aultoneal, S. Gaudio, K. Gill, E. M. Gretarsson, B. Hughey, M. Muratore, J. W. W. Pratt, S. G. Schwalbe, K. Staats, M. J. Szczepańczyk, M. Zanolin, Et Al. Dec 2017

On The Progenitor Of Binary Neutron Star Merger Gw170817, B. P. Abbott, K. Aultoneal, S. Gaudio, K. Gill, E. M. Gretarsson, B. Hughey, M. Muratore, J. W. W. Pratt, S. G. Schwalbe, K. Staats, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ~40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ~2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the …

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Evaporated Aluminum Fluoride As A Barrier Layer To Retard Oxidation Of Aluminum Mirrors, Margaret Miles Dec 2017

Evaporated Aluminum Fluoride As A Barrier Layer To Retard Oxidation Of Aluminum Mirrors, Margaret Miles

Theses and Dissertations

The aluminum oxide growth rate for aluminum protected with 2.4 nm of aluminum fluoride has been determined. We show that a 2.4 nm aluminum fluoride layer does not prevent aluminum from oxidation but does significantly retard the oxide growth – decreasing the oxide layer thickness from 1 nm in less than an hour to 0.9 nm over 116 hours. Additionally, the optical constants for aluminum oxide growing under an aluminum fluoride barrier layer have been determined – showing an increase in absorption at high energies for Al2O3 forming at room temperature as compared to highly ordered Al …

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Machine Learning To Discover And Optimize Materials, Conrad Waldhar Rosenbrock Dec 2017

Machine Learning To Discover And Optimize Materials, Conrad Waldhar Rosenbrock

Theses and Dissertations

For centuries, scientists have dreamed of creating materials by design. Rather than discovery by accident, bespoke materials could be tailored to fulfill specific technological needs. Quantum theory and computational methods are essentially equal to the task, and computational power is the new bottleneck. Machine learning has the potential to solve that problem by approximating material behavior at multiple length scales. A full end-to-end solution must allow us to approximate the quantum mechanics, microstructure and engineering tasks well enough to be predictive in the real world. In this dissertation, I present algorithms and methodology to address some of these problems at …

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The 13th Data Release Of The Sloan Digital Sky Survey: First Spectroscopic Data From The Sdss-Iv Survey Mapping Nearby Galaxies At Apache Point Observatory, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud Dec 2017

The 13th Data Release Of The Sloan Digital Sky Survey: First Spectroscopic Data From The Sdss-Iv Survey Mapping Nearby Galaxies At Apache Point Observatory, Franco D. Albareti, Carlos Allende Prieto, Andres Almeida, Friedrich Anders, Scott Anderson, Brett H. Andrews, Alfonso Aragón-Salamanca, Maria Argudo-Fernández, Eric Armengaud

Physics & Astronomy Faculty Publications

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It …

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Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares Icecube And The Pierre Auger Observatory, A. Albert, M. André, M. Anghinolfi, M. Ardid, J. J. Aubert, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Dec 2017

Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares Icecube And The Pierre Auger Observatory, A. Albert, M. André, M. Anghinolfi, M. Ardid, J. J. Aubert, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV-EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincident …

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Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey Carlin, David Sand, Ricardo Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Evan Kirby, Annika Peter, Aaron Romanowsky, Jay Strader Dec 2017

Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey Carlin, David Sand, Ricardo Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Evan Kirby, Annika Peter, Aaron Romanowsky, Jay Strader

Faculty Publications

We present deep, wide-field Subaru Hyper Suprime-Cam photometry of two recently discovered satellites of the Milky Way (MW): Columba I (Col I) and Triangulum II (Tri II). The color–magnitude diagrams of both objects point to exclusively old and metal-poor stellar populations. We re-derive structural parameters and luminosities of these satellites, and find  for Col I and  for Tri II, with corresponding half-light radii of  pc and  pc. The properties of both systems are consistent with observed scaling relations for MW dwarf galaxies. Based on archival data, we derive upper limits on the neutral gas content of these dwarfs, and find …

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Detection Of Survival And Proliferation Of Sulfate Reducers Under Simulated Martian Atmospheric And Soil Conditions, Sergio Mosquera Mora Dec 2017

Detection Of Survival And Proliferation Of Sulfate Reducers Under Simulated Martian Atmospheric And Soil Conditions, Sergio Mosquera Mora

Graduate Theses and Dissertations

Numerous studies have tried to determine the survivability and proliferation of microorganisms under simulated Martian conditions. Furthermore, most of them have been focused on the ability of these microbes to cope with high brines’ salt (NaCl) concentrations inherent of the Martian surface. However, there are not studies related to the ability of bacteria to survive on subsurface environments that have increasing concentrations of sulfate compounds. For this research, a group of microorganisms known as sulfate-reducing bacteria or simply sulfate reducers were chosen due to their ability to use sulfate compounds as terminal electron acceptors to produce metabolic energy, their tolerance …

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The Morphology And Uniformity Of Circumstellar Oh/H2O Masers Around Oh/Ir Stars, Derek Sean Felli Dec 2017

The Morphology And Uniformity Of Circumstellar Oh/H2O Masers Around Oh/Ir Stars, Derek Sean Felli

Theses and Dissertations

Even though low mass stars (< 8 solar masses) vastly outnumber high mass stars (< 8 solar masses), the more massive stars drive the chemical evolution of galaxies from which the next generation of stars and planets can form. Understanding mass loss of asymptotic giant branch stars contributes to our understanding of the chemical evolution of the galaxy, stellar populations, and star formation history. Stars with mass < 8 solar masses form planetary nebulae, while those with mass < 8 solar masses go supernova. In both cases, these stars enrich their environments with elements heavier than simple hydrogen and helium molecules. While some general info about how stars die and form planetary nebulae are known, specific details are missing due to a lack of high-resolution observations and analysis of the intermediate stages. For example, we know that mass loss in stars creates morphologically diverse planetary nebulae, but we do not know the uniformity of these processes, and therefore lack detailed models to better predict how spherically symmetric stars form asymmetric nebulae. We have selected a specific group of late-stage stars and observed them at different scales to reveal the uniformity of mass loss through different layers close to the star. This includes observing nearby masers that trace the molecular shell structure around these stars. This study revealed detailed structure that was analyzed for uniformity to place constraints on how the mass loss processes behave in models. These results will feed into our ability to create more detailed models to better predict the chemical evolution of the next generation of stars and planets.

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Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov Dec 2017

Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting …

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Testing The Wind-Shock Paradigm For B-Type Star X-Ray Production With Θ Carinae, Trisha F. Doyle Dec 2017

Testing The Wind-Shock Paradigm For B-Type Star X-Ray Production With Θ Carinae, Trisha F. Doyle

Theses and Dissertations

We present Chandra X-ray grating spectroscopy of the B0.2V star, θ Carinae. θ Car is in a critical transition region between the latest O-type and earliest B-type stars, where some of these stars are observed to have UV-determined mass-loss rates much lower than theoretically expected. In general, X-ray emission in this low-luminosity regime should be less prominent than in O-star winds, but observations have shown a higher than expected production of X-ray emission from the winds of these stars (e.g., Cohen et al. 2008; Huenemoerder et al. 2012). A hot wind could explain weak UV wind signatures, but this severely …

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Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares, Icecube, And The Pierre Auger Observatory, M. G. Aartsen, K. Aultoneal, S. Gaudio, K. Gill, E. M. Gretarsson, B. Hughey, M. Muratore, J. W. W. Pratt, S. G. Schwalbe, K. Staats, M. J. Szczepańczyk, M. Zanolin, Et Al. Dec 2017

Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares, Icecube, And The Pierre Auger Observatory, M. G. Aartsen, K. Aultoneal, S. Gaudio, K. Gill, E. M. Gretarsson, B. Hughey, M. Muratore, J. W. W. Pratt, S. G. Schwalbe, K. Staats, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV–EeV energy range using the ANTARES, IceCube, and Pierre Auger Observatories. No neutrinos directionally coincident …

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Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, B. P. Abbott, K. Aultoneal, S. Gaudio, K. Gill, E. M. Gretarsson, B. Hughey, M. Muratore, J. W. W. Pratt, S. G. Schwalbe, K. Staats, M. J. Szczepańczyk, M. Zanolin, Et Al. Dec 2017

Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, B. P. Abbott, K. Aultoneal, S. Gaudio, K. Gill, E. M. Gretarsson, B. Hughey, M. Muratore, J. W. W. Pratt, S. G. Schwalbe, K. Staats, M. J. Szczepańczyk, M. Zanolin, Et Al.

Publications

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the resulting …

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Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, Amanda Schilling Dec 2017

Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, Amanda Schilling

Graduate Theses and Dissertations

I have investigated the energy output of active galactic nuclei (AGN) in order to understand how these objects evolve and the impact they may have on host galaxies. First, I looked at a sample of 96 AGN at redshifts $z \sim 2, 3,$ and $4$ which have imaging and thus luminosity measurements in the $griz$ and $JHK$ observed wavebands. For these galaxies, I have co-epochal data across those bands which accounted for variability in AGN luminosity. I used the luminosity measurements in the five bands to construct spectral energy distributions (SED) in the emitted optical-UV bands for each AGN. I …

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Biases In Metallicity Measurements From Global Galaxy Spectra: The Effects Of Flux Weighting And Diffuse Ionized Gas Contamination, Ryan L. L. Sanders, Alice E. Shapley, Kai Zhang, Renbin Yan Nov 2017

Biases In Metallicity Measurements From Global Galaxy Spectra: The Effects Of Flux Weighting And Diffuse Ionized Gas Contamination, Ryan L. L. Sanders, Alice E. Shapley, Kai Zhang, Renbin Yan

Physics and Astronomy Faculty Publications

Galaxy metallicity scaling relations provide a powerful tool for understanding galaxy evolution, but obtaining unbiased global galaxy gas-phase oxygen abundances requires proper treatment of the various line-emitting sources within spectroscopic apertures. We present a model framework that treats galaxies as ensembles of H II and diffuse ionized gas (DIG) regions of varying metallicities. These models are based upon empirical relations between line ratios and electron temperature for H II regions, and DIG strong-line ratio relations from SDSS-IV MaNGA IFU data. Flux-weighting effects and DIG contamination can significantly affect properties inferred from global galaxy spectra, biasing metallicity estimates by more than …

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The Alma Early Science View Of Fuor/Exor Objects - V. Continuum Disc Masses And Sizes, Lucas Cieza, Dary Ruiz-Rodriguez, Sebastian Perez, Simon Casassus, Jonathan P. Williams, Alice Zurlo, David A. Principe, Antonio Hales, Jose L. Prieto, John J. Tobin, Zhaohuan Zhu, Sebastian Marino Nov 2017

The Alma Early Science View Of Fuor/Exor Objects - V. Continuum Disc Masses And Sizes, Lucas Cieza, Dary Ruiz-Rodriguez, Sebastian Perez, Simon Casassus, Jonathan P. Williams, Alice Zurlo, David A. Principe, Antonio Hales, Jose L. Prieto, John J. Tobin, Zhaohuan Zhu, Sebastian Marino

Physics & Astronomy Faculty Research

Low-mass stars build a significant fraction of their total mass during short outbursts of enhanced accretion known as FUor and EXor outbursts. FUor objects are characterized by a sudden brightening of ∼5 mag at visible wavelengths within 1 yr and remain bright for decades. EXor objects have lower amplitude outbursts on shorter time-scales. Here we discuss a 1.3 mm Atacama Large Millimeter/submillimeter Array (ALMA) mini-survey of eight outbursting sources (three FUors, four EXors, and the borderline object V1647 Ori) in the Orion Molecular Cloud. While previous papers in this series discuss the remarkable molecular outflows observed in the three FUor …

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Total Molecular Gas Masses Of Planck – Herschel Selected Strongly Lensed Hyper Luminous Infrared Galaxies, K. C. Harrington, M. S. Yun, B. Magnelli, D. T. Frayer, A. Karim, A. Weiß, D. Riechers, E. F. Jiménez-Andrade, D. Berman, James Lowenthal, F. Bertoldi Nov 2017

Total Molecular Gas Masses Of Planck – Herschel Selected Strongly Lensed Hyper Luminous Infrared Galaxies, K. C. Harrington, M. S. Yun, B. Magnelli, D. T. Frayer, A. Karim, A. Weiß, D. Riechers, E. F. Jiménez-Andrade, D. Berman, James Lowenthal, F. Bertoldi

Astronomy: Faculty Publications

We report the detection of CO(1–0) line emission from seven Planck and Herschel selected hyper luminous (LIR(8−1000μm) > 1013 L⊙) infrared galaxies with the Green Bank Telescope (GBT). CO(1–0) measurements are a vital tool to trace the bulk molecular gas mass across all redshifts. Our results place tight constraints on the total gas content of these most apparently luminous high-z star-forming galaxies (apparent IR luminosities of LIR > 1013 − 14 L⊙), while we confirm their predetermined redshifts measured using the Large Millimeter Telescope, LMT (zCO = 1.33–3.26). The CO(1–0) lines show similar profiles as compared to Jup = 2–4 transitions previously …

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An Exactly Solvable Quench Protocol For Integrable Spin Models, Diptarka Das, Sumit R. Das, Damián A. Galante, Robert C. Myers, Krishnendu Sengupta Nov 2017

An Exactly Solvable Quench Protocol For Integrable Spin Models, Diptarka Das, Sumit R. Das, Damián A. Galante, Robert C. Myers, Krishnendu Sengupta

Physics and Astronomy Faculty Publications

Quantum quenches in continuum field theory across critical points are known to display different scaling behaviours in different regimes of the quench rate. We extend these results to integrable lattice models such as the transverse field Ising model on a one-dimensional chain and the Kitaev model on a two-dimensional honeycomb lattice using a nonlinear quench protocol which allows for exact analytical solutions of the dynamics. Our quench protocol starts with a finite mass gap at early times and crosses a critical point or a critical region, and we study the behaviour of one point functions of the quenched operator at …

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Hypervolatiles In A Jupiter-Family Comet: Observations Of 45p/Honda–Mrkos–Pajdušáková Using Ishell At The Nasa-Irtf, Michael Disanti, Boncho Bonev, Neil Russo, Ronald Vervack, Erika Gibb, Nathan Roth, Adam Mckay, Hideyo Kawakita, Lori Feaga, Harold Weaver Nov 2017

Hypervolatiles In A Jupiter-Family Comet: Observations Of 45p/Honda–Mrkos–Pajdušáková Using Ishell At The Nasa-Irtf, Michael Disanti, Boncho Bonev, Neil Russo, Ronald Vervack, Erika Gibb, Nathan Roth, Adam Mckay, Hideyo Kawakita, Lori Feaga, Harold Weaver

Physics Faculty Works

We used the new high spectral resolution cross-dispersed facility spectrograph, iSHELL, at the NASA Infrared Telescope Facility on Maunakea, HI, to observe Jupiter-family comet (JFC) 45P/Honda–Mrkos–Pajdušáková. We report water production rates, as well as production rates and abundance ratios relative to H2O, for eight trace parent molecules (native ices), CO, CH4, H2CO, CH3OH, HCN, NH3, C2H2, and C2H6, on 2 days spanning UT 2017 January 6/7 and 7/8, shortly following perihelion. Trace species were measured simultaneously with H2O and/or OH prompt emission, a proxy for H2O production, thereby providing a robust and consistent means of establishing the native ice composition …

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On The Time Variation Of Dust Extinction And Gas Absorption For Type Ia Supernovae Observed Through A Nonuniform Interstellar Medium, Xiaosheng Huang, G Aldering, M. Biederman, B. Herger Nov 2017

On The Time Variation Of Dust Extinction And Gas Absorption For Type Ia Supernovae Observed Through A Nonuniform Interstellar Medium, Xiaosheng Huang, G Aldering, M. Biederman, B. Herger

Physics and Astronomy

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures () will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent …

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An X-Ray Study Of Two B+B Binaries: Ah Cep And Cw Cep, Richard Ignace, K. T. Hole, Lidia M. Oskinova, J. P. Rotter Nov 2017

An X-Ray Study Of Two B+B Binaries: Ah Cep And Cw Cep, Richard Ignace, K. T. Hole, Lidia M. Oskinova, J. P. Rotter

ETSU Faculty Works

AH Cep and CW Cep are both early B-type binaries with short orbital periods of 1.8 days and 2.7 days, respectively. All four components are B0.5V types. The binaries are also double-lined spectroscopic and eclipsing. Consequently, solutions for orbital and stellar parameters make the pair of binaries ideal targets for a study of the colliding winds between two B stars. Chandra ACIS-I observations were obtained to determine X-ray luminosities. AH Cep was detected with an unabsorbed X-ray luminosity at a 90% confidence interval of erg s−1, or , relative to the combined Bolometric luminosities of the two components. While formally …

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Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron Romanowsky, Pieter Van Dokkum Nov 2017

Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron Romanowsky, Pieter Van Dokkum

Faculty Publications

Analyses of strong gravitational lenses, galaxy-scale kinematics, and absorption-line stellar population synthesis (SPS) have all concluded that the stellar initial mass function (IMF) varies within the massive early-type galaxy (ETG) population. However, the physical mechanism that drives variation in the IMF is an outstanding question. Here we use new SPS models to consider a diverse set of compact, low-velocity dispersion stellar systems: globular clusters (GCs), an ultra-compact dwarf (UCD), and the compact elliptical (cE) galaxy M32. We compare our results to massive ETGs and available dynamical measurements. We find that the GCs have stellar mass-to-light ratios (M/L) that are either …

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Evolution Of Galactic Outflows At Z ~ 0–2 Revealed With Sdss, Deep2, And Keck Spectra, Yuma Sugahara, Masami Ouchi, Lihwai Lin, Crystal L. Martin, Yoshiaki Ono, Yuichi Harikane, Takatoshi Shibuya, Renbin Yan Nov 2017

Evolution Of Galactic Outflows At Z ~ 0–2 Revealed With Sdss, Deep2, And Keck Spectra, Yuma Sugahara, Masami Ouchi, Lihwai Lin, Crystal L. Martin, Yoshiaki Ono, Yuichi Harikane, Takatoshi Shibuya, Renbin Yan

Physics and Astronomy Faculty Publications

We conduct a systematic study of galactic outflows in star-forming galaxies at z ~ 0–2 based on the absorption lines of optical spectra taken from SDSS DR7, DEEP2 DR4, and Keck (Erb et al.). We carefully make stacked spectra of homogeneous galaxy samples with similar stellar mass distributions at z ~ 0–2 and perform the multicomponent fitting of model absorption lines and stellar continua to the stacked spectra. We obtain the maximum (vmax) and central (vout) outflow velocities and estimate the mass loading factors (η), a ratio of the mass outflow rate …

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The Discovery And Mass Measurement Of A New Ultra-Short-Period Planet: K2-131b, Fei Dai, Joshua N. Winn, Davide Gandolfi, Sharon X. Wang, Johanna K. Teske, Jennifer Burt, Simon Albrecht, Oscar Barragán, William D. Cochran, Michael Endl, Malcolm Fridlund, Artie P. Hatzes, Teruyuki Hirano, Lea A. Hirsch, Marshall C. Johnson, Anders Bo Justesen, John Livingston, Carina M. Persson, Jorge Prieto-Arranz, Andrew Vanderburg, Roi Alonso, Giuliano Antoniciello, Pamela Arriagada, R. Paul Butler, Juan Cabrera, Jeffrey D. Crane, Felice Cusano, Szilárd Csizmadia, Hans Deeg, Sergio B. Dieterich, Philipp Eigmüller, Anders Erikson, Mark E. Everett, Akihiko Fukui, Sascha Grziwa, Eike W. Guenther, Gregory W. Henry, Steve B. Howell, John Asher Johnson, Judith Korth, Masayuki Kuzuhara, Norio Narita, David Nespral, Grzegorz Nowak, Enric Palle, Martin Pätzold, Heike Rauer, Pilar Montañés Rodríguez, Stephen A. Shectman, Alexis M. S. Smith, Ian B. Thompson, Vincent Van Eylen, Michael W. Williamson, Robert A. Wittenmyer Nov 2017

The Discovery And Mass Measurement Of A New Ultra-Short-Period Planet: K2-131b, Fei Dai, Joshua N. Winn, Davide Gandolfi, Sharon X. Wang, Johanna K. Teske, Jennifer Burt, Simon Albrecht, Oscar Barragán, William D. Cochran, Michael Endl, Malcolm Fridlund, Artie P. Hatzes, Teruyuki Hirano, Lea A. Hirsch, Marshall C. Johnson, Anders Bo Justesen, John Livingston, Carina M. Persson, Jorge Prieto-Arranz, Andrew Vanderburg, Roi Alonso, Giuliano Antoniciello, Pamela Arriagada, R. Paul Butler, Juan Cabrera, Jeffrey D. Crane, Felice Cusano, Szilárd Csizmadia, Hans Deeg, Sergio B. Dieterich, Philipp Eigmüller, Anders Erikson, Mark E. Everett, Akihiko Fukui, Sascha Grziwa, Eike W. Guenther, Gregory W. Henry, Steve B. Howell, John Asher Johnson, Judith Korth, Masayuki Kuzuhara, Norio Narita, David Nespral, Grzegorz Nowak, Enric Palle, Martin Pätzold, Heike Rauer, Pilar Montañés Rodríguez, Stephen A. Shectman, Alexis M. S. Smith, Ian B. Thompson, Vincent Van Eylen, Michael W. Williamson, Robert A. Wittenmyer

Information Systems and Engineering Management Research Publications

We report the discovery of a new ultra-short-period planet and summarize the properties of all such planets for which the mass and radius have been measured. The new planet, K2-131b, was discovered in K2 Campaign 10. It has a radius of ${1.81}_{-0.12}^{+0.16}\,{R}_{\oplus }$ and orbits a G dwarf with a period of 8.9 hr. Radial velocities obtained with Magellan/PFS and TNG/HARPS-N show evidence for stellar activity along with orbital motion. We determined the planetary mass using two different methods: (1) the "floating chunk offset" method, based only on changes in velocity observed on the same night; and (2) a Gaussian …

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Sdss-Iv Manga: Constraints On The Conditions For Star Formation In Galaxy Discs, David V. Stark, Kevin A. Bundy, Matthew E. Orr, Philip F. Hopkins, Kyle Westfall, Matthew Bershady, Cheng Li, Dmitry Bizyaev, Karen L. Masters, Anne-Marie Weijmans, Ivan Lacerna, Daniel Thomas, Niv Drory, Renbin Yan, Kai Zhang Nov 2017

Sdss-Iv Manga: Constraints On The Conditions For Star Formation In Galaxy Discs, David V. Stark, Kevin A. Bundy, Matthew E. Orr, Philip F. Hopkins, Kyle Westfall, Matthew Bershady, Cheng Li, Dmitry Bizyaev, Karen L. Masters, Anne-Marie Weijmans, Ivan Lacerna, Daniel Thomas, Niv Drory, Renbin Yan, Kai Zhang

Physics and Astronomy Faculty Publications

Regions of disc galaxies with widespread star formation tend to be both gravitationally unstable and self-shielded against ionizing radiation, whereas extended outer discs with little or no star formation tend to be stable and unshielded on average. We explore what drives the transition between these two regimes, specifically whether discs first meet the conditions for self-shielding (parametrized by dust optical depth, τ) or gravitational instability (parametrized by a modified version of Toomre's instability parameters, Qthermal, which quantifies the stability of a gas disc that is thermally supported at T = 104 K). We first introduce a new …

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Ion-Scale Wave Properties And Enhanced Ion Heating Across The Low-Latitude Boundary Layer During Kelvin-Helmholtz Instability, T. W. Moore, K. Nykyri, A. P. Dimmock Nov 2017

Ion-Scale Wave Properties And Enhanced Ion Heating Across The Low-Latitude Boundary Layer During Kelvin-Helmholtz Instability, T. W. Moore, K. Nykyri, A. P. Dimmock

Publications

In the Earth's magnetosphere, the magnetotail plasma sheet ions are much hotter than in the shocked solar wind. On the dawn sector, the cold-component ions are more abundant and hotter by 30–40% when compared to the dusk sector. Recent statistical studies of the flank magnetopause and magnetosheath have shown that the level of temperature asymmetry of the magnetosheath is unable to account for this, so additional physical mechanisms must be at play, either at the magnetopause or plasma sheet that contributes to this asymmetry. In this study, we perform a statistical analysis on the ion-scale wave properties in the three …

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Discovery Of Very-High-Energy Emission From Rgb J2243+203 And Derivation Of Its Redshift Upper Limit, P. T. Reynolds, Et Al Nov 2017

Discovery Of Very-High-Energy Emission From Rgb J2243+203 And Derivation Of Its Redshift Upper Limit, P. T. Reynolds, Et Al

Physical Sciences Publications

Very-high-energy (VHE; > 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 2014 December 21 and 24. The VERITAS energy spectrum from this source can be fitted by a power law with a photon index of 4.6 ± 0.5, and a flux normalization at 0.15 TeV of . The integrated Fermi-LAT flux from 1 to 100 GeV during the VERITAS detection is , which is an order of magnitude larger than the four-year-averaged flux in the same energy range reported in the 3FGL catalog, (). The detection with …

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Proposed Method For Measuring The Let Of Radiotherapeutic Particle Beams, Stephen D. Bello Nov 2017

Proposed Method For Measuring The Let Of Radiotherapeutic Particle Beams, Stephen D. Bello

Physics & Astronomy ETDs

The Bragg peak geometry of the depth dose distributions for hadrons allows for precise and effective dose delivery to tumors while sparing neighboring healthy tissue. Further, compared against other forms of radiotherapeutic treatments, such as electron beam therapy (EBT) or photons (x and \(\gamma\)-rays), hadrons create denser ionization events along the particle track, which induces irreparable damage to DNA, and thus are more effective at inactivating cancerous cells. The measurement of radiation's ability to inactivate cellular reproduction is the relative biological effectiveness (RBE). A quality related to the RBE that is a measurable physical property is the linear energy transfer …

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