Astrophysics and Astronomy Commons^™

Mapping Gravitational-Wave Backgrounds Using Methods From Cmb Analysis: Application To Pulsar Timing Arrays, Jonathan Gair, Joseph D. Romano, Stephen Taylor, Chiara M. F. Mingarelli

Physics & Astronomy Faculty Publications

We describe an alternative approach to the analysis of gravitational-wave backgrounds, based on the formalism used to characterize the polarization of the cosmic microwave background. In contrast to standard analyses, this approach makes no assumptions about the nature of the background and so has the potential to reveal much more about the physical processes that generated it. An arbitrary background can be decomposed into modes whose angular dependence on the sky is given by gradients and curls of spherical harmonics. We derive the pulsar timing overlap reduction functions for the individual modes, which are given by simple combinations of spherical …

Characterizing The Ab Doradus Moving Group Via High-Resolution Spectroscopy And Kinematic Traceback, Kyle Mccarthy, Ronald J. Wilhelm

Physics and Astronomy Faculty Publications

We present a detailed analysis of 10 proposed F and G members of the nearby, young moving group AB Doradus (ABD). Our sample was obtained using the 2.7 m telescope at the McDonald Observatory with the coude echelle spectrograph, achieving R ~ 60,000 and signal-to-noise ratio ~200. We derive spectroscopic T _eff, log(g), [Fe/H], and microturbulance (v_t ) using a bootstrap method of the TGVIT software resulting in typical errors of 33K in T _eff, 0.08 dex in log(g), 0.03 dex in [Fe/H], and 0.13 km s^–1 in v_t . …

No More Active Galactic Nuclei In Clumpy Disks Than In Smooth Galaxies At Z ~ 2 In Candels/3d-Hst*, Jonathan R. Trump, Guillermo Barro, Stéphanie Juneau, Benjamin J. Weiner, Bin Luo, Gabriel B. Brammer, Eric F. Bell, W. N. Brandt, Avishai Dekel, Yicheng Guo, Philip F. Hopkins, David C. Koo, Dale D. Kocevski, Daniel H. Mcintosh, Ivelina Momcheva, S. M. Faber, Henry C. Ferguson, Norman A. Grogin, Jeyhan Kartaltepe, Anton M. Koekemoer, Jennifer Lotz, Michael Maseda, Mark Mozena, Kirpal Nandra, David J. Rosario, Gergory R. Zeimann

Physics and Astronomy Faculty Publications

We use CANDELS imaging, 3D-HST spectroscopy, and Chandra X-ray data to investigate if active galactic nuclei (AGNs) are preferentially fueled by violent disk instabilities funneling gas into galaxy centers at 1.3 < z < 2.4. We select galaxies undergoing gravitational instabilities using the number of clumps and degree of patchiness as proxies. The CANDELS visual classification system is used to identify 44 clumpy disk galaxies, along with mass-matched comparison samples of smooth and intermediate morphology galaxies. We note that despite being mass-matched and having similar star formation rates, the smoother galaxies tend to be smaller disks with more prominent bulges compared to the clumpy galaxies. The lack of smooth extended disks is probably a general feature of the z ~ 2 galaxy population, and means we cannot directly compare with the clumpy and smooth extended disks observed at lower redshift. We find that z ~ 2 clumpy galaxies have slightly enhanced AGN fractions selected by integrated line ratios (in the mass-excitation method), but the spatially resolved line ratios indicate this is likely due to extended phenomena rather than nuclear AGNs. Meanwhile, the X-ray data show that …

2014 Scas Annual Meeting Program

Journal of the South Carolina Academy of Science

No abstract provided.

Scas Officers And Council Members 2014-2015

Journal of the South Carolina Academy of Science

No abstract provided.

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

Alleviating Polarity-Conflict At The Heterointerfaces Of Ktao3/Gdsco3 Polar Complex-Oxides, Justin K. Thompson, J. Hwang, John Nichols, John G. Connell, S. Stemmer, Sung S. Ambrose Seo

Physics and Astronomy Faculty Publications

We have synthesized and investigated the heterointerfaces of KTaO₃ (KTO) and GdScO₃ (GSO), which are both polar complex-oxides along the pseudo-cubic [001] direction. Since their layers have the same, conflicting net charges at interfaces, i.e., KO(−1)/ScO₂(−1) or TaO₂(+1)/GdO(+1), forming the heterointerface of KTO/GSO should be forbidden due to strong Coulomb repulsion, the so-called polarity conflict. However, we have discovered that atomic reconstruction occurs at the heterointerfaces between KTO thin-films and GSO substrates, which effectively alleviates the polarity conflict without destroying the hetero-epitaxy. Our result demonstrates one of the important ways to create artificial heterostructures …

Tunable Magnetic Properties Of Transition Metal Doped Mos2, Antonis N. Andiotis, Madhu Menon

Physics and Astronomy Faculty Publications

We report a detailed investigation of the electronic and magnetic properties of the transition metal (TM) doped two-dimensional (2D) MoS₂ using ab initio calculations. The doping is achieved by substituting two or more Mo atoms by TM atoms of the 3d series. Additionally, the effect of codoping on the 2D MoS₂ by cation-cation and cation-anion pairs is also investigated. Our results demonstrate that the TM doping of 2D MoS₂ leads to a significant reduction of the energy gap and the appearance of magnetic features whose major characteristic is the ferromagnetic coupling of the TM dopants. The …

On The Momentum Dependence Of The Flavor Structure Of The Nucleon Sea, Jen-Chieh Peng, Wen-Chen Chang, Hai-Yang Cheng, Tie-Jiun Hou, Keh-Fei Liu, Jian-Wei Qiu

Physics and Astronomy Faculty Publications

Difference between the u¯ and d¯ sea quark distributions in the proton was first observed in the violation of the Gottfried sum rule in deep-inelastic scattering (DIS) experiments. The parton momentum fraction x dependence of this difference has been measured over the region 0.02 < x < 0.35 from Drell–Yan and semi-inclusive DIS experiments. The Drell–Yan data suggested a possible sign-change for d¯(x) − u¯ (x) near x ~ 0.3, which has not yet been explained by existing theoretical models. We present an independent evidence for the d¯(x) − u¯ (x) sign-change at x ~ 0.3 from an analysis of the DIS data. We further discuss the x …

Theoretical And Experimental Infrared Spectra Of Hydrated And Dehydrated Sulfonated Poly(Ether Ether Ketone), Jonathan Doan, Erin Kingston, Ian Kendrick, Kierstyn Anderson, Nicholas Dimakis, Philippe Knauth, Maria Luisa Di Vona, Eugene S. Smotkina

Physics & Astronomy Faculty Publications

Time-dependent FT-IR spectra of sulfonated poly(ether ether ketone) during dehydration show diminishing 1081 cm−1 and 1023 cm−1 band intensities concurrent with the emergence and shifting of bands at 1362 cm−1 and 898 cm−1. Animations of density functional theory calculated normal modes enable assignment of the 1081 cm−1 and 1023 cm−1 bands as group modes that include a sulfonate exchange site with C3v local symmetry, while the 1362 cm−1 and 898 cm−1 bands are assigned as group modes that include an associated sulfonic acid with no local symmetry (C1). In contrast to analogously assigned Nafion group mode bands, the SPEEK C3v …

Recent Ideas On The Calculation Of Lepton Anomalous Magnetic Moments, Michael I. Eides

Physics and Astronomy Faculty Publications

We discuss the recent claim [G. Mishima, arXiv:1311.7109; M. Fael and M. Passera, arXiv:1402.1575 [Phys. Rev. D (to be published)]] about discovery of a nonperturbative quantum-electrodynamic contribution of order (α/π)⁵ to lepton anomalous magnetic moments. We explain why this nonperturbative correction does not exist.

First All-Sky Search For Continuous Gravitational Waves From Unknown Sources In Binary Systems, J. Aasi, B. P. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov

Physics & Astronomy Faculty Publications

We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO science run and the second and third Virgo science runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ∼2; 254 h and a frequency- and period-dependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range …

Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au+Au Collisions At Rhic, J. Kevin Adkins, Renee Fatemi, Wolfgang Korsch, Suvarna Ramachandran, G. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer

Physics and Astronomy Faculty Publications

We report the first measurements of the moments—mean (M), variance (σ²), skewness (S), and kurtosis (κ)—of the net-charge multiplicity distributions at midrapidity in Au+Au collisions at seven energies, ranging from √^S_NN=7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ²/M, Sσ, and κσ², with the expectations …

Thermal Diffusivities Of Functionalized Pentacene Semiconductors, Hao Zhang, Yulong Yao, Marcia M. Payne, John E. Anthony, Joseph W. Brill

Physics and Astronomy Faculty Publications

We have measured the interlayer and in-plane (needle axis) thermal diffusivity of 6,13-bis(triisopropylsilylethynyl) pentacene. The needle axis value is comparable to the phonon thermal diffusivities of quasi-one dimensional organic metals with excellent π-orbital overlap, and its value suggests that a significant fraction of heat is carried by optical phonons. Furthermore, the interlayer (c-axis) thermal diffusivity is at least an order of magnitude larger, and this unusual anisotropy implies very strong dispersion of optical modes in the interlayer direction, presumably due to interactions between the silyl-containing side groups. Similar values for both in-plane and interlayer diffusivities have been observed for several …

The Meaning Of Wise Colours – I. The Galaxy And Its Satellites, Robert Nikutta, Nicholas Hunt-Walker, Maia M. Nenkova, Željko Ivezić, Moshe Elitzur

Physics and Astronomy Faculty Publications

Through matches with the Sloan Digital Sky Survey (SDSS) catalogue we identify the location of various families of astronomical objects in WISE colour space. We identify reliable indicators that separate Galactic/local from extragalactic sources and concentrate here on the objects in our Galaxy and its closest satellites. We develop colour and magnitude criteria that are based only on WISE data to select asymptotic giant branch (AGB) stars with circumstellar dust shells, and separate them into O-rich and C-rich classes. With these criteria we produce an all-sky map for the count ratio of the two populations. The map reveals differences between …

Measurement Of Longitudinal Spin Asymmetries For Weak Boson Production In Polarized Proton-Proton Collisions At Rhic, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, G. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer

Physics and Astronomy Faculty Publications

We report measurements of single- and double-spin asymmetries for W^± and Z/γ^∗ boson production in longitudinally polarized p+p collisions at √^S=510  GeV by the STAR experiment at RHIC. The asymmetries for W^± were measured as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the proton’s polarized quark distributions at the scale of the W mass. The results are compared to theoretical predictions, constrained by polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range 0.05<x<0.2.

J/Ψ Production At Low PT In Au + Au And Cu + Cu Collisions At √SNn = 200 Gev With The Star Detector, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin

Physics and Astronomy Faculty Publications

The J/ψ p_T spectrum and nuclear modification factor (R_AA) are reported for p_T < 5 GeV/c and |y| < 1 from 0% to 60% central Au + Au and Cu + Cu collisions at √^SNN = 200 GeV at STAR. A significant suppression of p_T-integrated J/ψ production is observed in central Au + Au events. The Cu + Cu data are consistent with no suppression, although the precision is limited by the available statistics. R_AA in Au + Au collisions exhibits a strong suppression at low transverse momentum and gradually increases with p_T. The data are compared to high-p_{T …}

Star Formation Quenching In High-Redshift Large-Scale Structure: Post-Starburst Galaxies In The Ci 1604 Supercluster At Z ~ 0.9, Po-Feng Wu, Roy R. Gal, Brian C. Lemaux, Dale D. Kocevski, Lori M. Lubin, Nicholas Rumbaugh, Gordon K. Squires

Physics and Astronomy Faculty Publications

The Cl 1604 supercluster at z ~ 0.9 is one of the most extensively studied high-redshift large-scale structures, with more than 500 spectroscopically confirmed members. It consists of eight clusters and groups, with members numbering from a dozen to nearly a hundred, providing a broad range of environments for investigating the large-scale environmental effects on galaxy evolution. Here we examine the properties of 48 post-starburst galaxies in Cl 1604, comparing them to other galaxy populations in the same supercluster. Incorporating photometry from ground-based optical and near-infrared imaging, along with Spitzer mid-infrared observations, we derive stellar masses for all Cl 1604 …

Characterizing New Calibration Sources In Liquid Xenon Dark Matter Searches, Evan P. Bray, Rafael Lang, Sean Macmullin

The Summer Undergraduate Research Fellowship (SURF) Symposium

In order to use the XENON1T liquid xenon detector as a means for detecting dark matter, the response to nuclear and electronic recoils must be well calibrated. Electronic-recoil calibration of XENON1T will be done by using the noble gas radon-220 that emanates from a custom thorium-228 source to observe the electron recoils that its daughter elements induce in liquid xenon. A silicon PIN diode was constructed to ensure that the Th228 source does not contaminate the system with the long-lived isotopes Th228 (T1/2 of 1.9 y) or Radium-224 (T1/2 of 3.6 d). The PIN diode was fixed in a custom …

C/2013 R1 (Lovejoy) At Ir Wavelengths And The Variability Of Co Abundances Among Oort Cloud Comets, L. Paganini, M. Mumma, G. Villanueva, J. Keane, G. Blake, B. Bonev, M. Disanti, E. Gibb, K. Meech

Physics Faculty Works

We report production rates, rotational temperatures, and related parameters for gases in C/2013 R1 (Lovejoy) using the Near InfraRed SPECtrometer at the Keck Observatory, on six UT dates spanning heliocentric distances (Rh ) that decreased from 1.35 AU to 1.16 AU (pre-perihelion). We quantified nine gaseous species (H2O, OH*, CO, CH4, HCN, C2H6, CH3OH, NH3, and NH2) and obtained upper limits for two others (C2H2 and H2CO). Compared with organics-normal comets, our results reveal highly enriched CO, (at most) slightly enriched CH3OH, C2H6, and HCN, and CH4 consistent with "normal", yet depleted, NH3, C2H2, and H2CO. Rotational temperatures increased from …

Laser Frequency Stabilization For Lisa, Andrew B. Parker, Andrew J. Sutton, Glenn De Vine

STAR Program Research Presentations

This research focuses on laser ranging developments for LISA (Laser Interferometer Space Antenna), a planned NASA-ESA gravitational wave detector in space. LISA will utilize precision laser interferometry to track the changes in separation between three satellites orbiting 5 million kilometers apart. Specifically, our goal is to investigate options for laser frequency stabilization. Previous research has shown that an optical cavity system can meet LISA's stability requirements, but these units are large and heavy, adding cost to the implementation. A heterodyne Mach-Zehnder interferometer could be integrated onto LISA’s existing optical bench, greatly reducing the weight, provided the interferometer meets the stability …

Environmental Testing Of Lasers For Jpl's Cold Atom Laboratory, Carey L. Baxter

STAR Program Research Presentations

NASA’s Cold Atom Lab (CAL) is a multi-user facility designed to study ultra-cold quantum gases in the microgravity environment of the International Space Station (ISS). One of the main goals of CAL is to explore the unknown territory of extremely low temperatures—possibly as low as the picokelvin range!—where new and fascinating quantum phenomena can be observed. At such temperatures matter stops behaving as particles and instead becomes macroscopic matter waves. CAL will be remotely controlled to perform a multitude of experiments and is scheduled to launch in 2016. In order to anticipate problems that might occur during and post-launch, including …

Maximizing Precision Of Variable Star Photometry With Digital Cameras In Suburban Environments, David Hergesheimer

STAR Program Research Presentations

Photometry is the measure of the brightness of an object. When making such measurements on stars, it is done is units of magnitude, which is on a logarithmic scale with a base of ~2.512. Variable star photometry using a commercially available digital camera is not going to be as accurate and precise as equipment used by astronomers, and because of the logarithmic scale of magnitude used, determining how much of an effect different error reduction strategies have is not straightforward, and is best done experimentally.

My research is conducting photometry on variable stars (changing brightness) with a digital camera, and …

Nonperturbative Renormalization Of Overlap Quark Bilinears On 2+1-Flavor Domain Wall Fermion Configurations, Zhaofeng Liu, Ying Chen, Shao-Jing Dong, Michael Glatzmaier, Ming Gong, Anyi Li, Keh-Fei Liu, Yi-Bo Yang, Jian-Bo Zhang

Physics and Astronomy Faculty Publications

We present renormalization constants of overlap quark bilinear operators on 2+1-flavor domain wall fermion configurations. . . .

For the remainder of the abstract, please visit: http://dx.doi.org/10.1103/PhysRevD.90.034505

Beam-Energy Dependence Of Charge Separation Along The Magnetic Field In Au+Au Collisions At Rhic, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, G. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer

Physics and Astronomy Faculty Publications

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with …

A Physically-Based Type Ii Supernova Feedback Model In Sph Simulations, Keita Todoroki

UNLV Theses, Dissertations, Professional Papers, and Capstones

We implement and test a core-collapse Type II SN feedback that is physically motivated and produces good agreement with observations in galaxy formation simulations. The model includes both kinetic and thermal feedback, allowing wind particles to receive a velocity kick that mimics galactic winds and distributes mass and metallicity to the interstellar and intergalactic medium. We also include a phenomenological stellar feedback to study a possible enhancement of the efficiency of the SN-II feedback by creating lower-density ambient gas medium of the stellar populations by distribution of thermal energy. Our SN-II model is unique in the sense that it computes …

The Experiences Of Women In Post Graduate Physics And Astronomy Programs: The Roles Of Support, Career Goals, And Gendered Experiences, Ramón S. Barthelemy

Dissertations

In physics and astronomy the low representation of women is obvious at every stage of the educational pathway from undergraduate students to full professors. These low numbers perpetuate themselves by failing to create new mentors to foster the next generation of women. Women and men also have different experiences as they traverse into physics and astronomy careers. Women often experience chilly climates, discrimination, and challenges coordinating the demands of young families with their careers. In the literature exploring this topic, little focus is put on the experiences of women graduate students in physics and no focus is put on women …

Suppression Of Υ Production In D + Au And Au + Au Collisions At √SNn = 200 Gev, James K. Adkins, Renee Fatemi, Wolfgang Korsch, Suvarna Ramachandran, L. Adamczyk, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee

Physics and Astronomy Faculty Publications

We report measurements of Υ meson production in p + p, d + Au, and Au + Au collisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au + Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Υ (1S + …

The Magnetopause: Bringing Space Physics Into A Junior Lab, Jim Crumley, Ari Palczewski,, Stephen Kaster

MapCores Faculty Publications

Undergraduate students often have minimal exposure to many subfields
of physics which are active areas of research. Space physics
is an area that is particularly difficult to expose students to since
it builds off of another area that most undergraduates see little of,
plasma physics. The magnetopause is convenient entry point
into space physics, since it can be modeled as a pressure balance, which is
a concept familiar from introductory physics. We use the Earth's
magnetopause as the basis for a lab for junior physics majors. In
the lab students analyze results from a NASA MHD simulation and
data from …

Candels+3d-Hst: Compact Sfgs At Z ~ 2-3, The Progenitors Of The First Quiescent Galaxies, G. Barro, S. M. Faber, P. G. Pérez-González, C. Pacifici, J. R. Trump, D. C. Koo, S. Wuyts, Y. Guo, E. Bell, A. Dekel, L. Porter, J. Primack, H. Ferguson, M. L. N. Ashby, K. Caputi, D. Ceverino, D. Croton, G. G. Fazio, M. Giavalisco, L. Hsu, Dalibor D. Kocevski, A. Koekemoer, P. Kurcynski, P. Kollipara, J. Lee, D. H. Mcintosh, E. Mcgrath, C. Moody, R. Somerville, C. Papovich, M. Salvato, P. Santini, T. Tal, A. Van Der Wel, C. C. Williams, S. P. Willner, A. Zolotov

Physics and Astronomy Faculty Publications

We analyze the star-forming and structural properties of 45 massive (log(M/M _☉) >10) compact star-forming galaxies (SFGs) at 2 < z < 3 to explore whether they are progenitors of compact quiescent galaxies at z ~ 2. The optical/NIR and far-IR Spitzer/Herschel colors indicate that most compact SFGs are heavily obscured. Nearly half (47%) host an X-ray-bright active galactic nucleus (AGN). In contrast, only about 10% of other massive galaxies at that time host AGNs. Compact SFGs have centrally concentrated light profiles and spheroidal morphologies similar to quiescent galaxies and are thus strikingly different from other SFGs, which typically are disk-like and sometimes clumpy or irregular. Most compact …