Physical Sciences and Mathematics Commons^™

Three X-Ray Transients In M31 Oberserved With Swift, R. Voss, W. Pietsch, F. Haberl, H. Stiele, J. Greiner, G. Sala, Dieter H. Hartmann, D. Hatzidimitriou

Publications

Aims.The purpose of this study is to find transient X-ray sources in M 31, and to investigate and classify their nature.Methods.Three X-ray transients were observed with Swift. For each of the three X-ray transients we use the Swift X-ray and opticaldata together with observations from XMM-Newton and Chandra to investigate the lightcurves and the spectra of the outburst, andthereby to identify the source types. Results.The outburst of XMMU J004215.8+ 411924 lasted for about one month. The source had a hard power-law spectrum with aphoton index of 1.6. It was previously identified as a Be/X-ray binary based on the optical identification …

Table Of Contents, Michele Harmon

Journal of the South Carolina Academy of Science

No abstract provided.

A Search For Enhanced Very High Energy Gamma-Ray Emission From The 2013 March Crab Nebula Flare, P. T. Reynolds, Et Al

Physical Sciences Publications

In 2013 March, a flaring episode from the Crab Nebula lasting ~2 weeks was detected by Fermi-LAT (Large Area Telescope on board the Fermi Gamma-ray Space Telescope). The Very Energetic Radiation Imaging Telescope Array System (VERITAS) provides simultaneous observations throughout this period. During the flare, Fermi-LAT detected a 20 fold increase in flux above the average synchrotron flux >100 MeV seen from the Crab Nebula. Simultaneous measurements with VERITAS are consistent with the non-variable long-term average Crab Nebula flux at TeV energies. Assuming a linear correlation between the very high energy flux change >1 TeV and the flux …

A Survey For Very Short-Period Planets In The Kepler Data, Brian Jackson, Christopher C. Stark, Elisabeth R. Adams, John Chambers, Drake Deming

Brian Jackson

We conducted a search for very short-period transiting objects in the publicly available Kepler data set. Our preliminary survey has revealed four planetary candidates, all with orbital periods less than 12 hr. We have analyzed the data for these candidates using photometric models that include transit light curves, ellipsoidal variations, and secondary eclipses to constrain the candidates’ radii, masses, and effective temperatures. Even with masses of only a few Earth masses, the candidates’ short periods mean that they may induce stellar radial velocity signals (a few m s−1) detectable by currently operating facilities. The origins of such short-period planets are …

Long Term Observations Of B2 1215+30 With Veritas, E. Aliu, S. Archambault, T. Arlen, T. Aune, M. Beilicke, W. Benbow, R. Bird, A. Bouvier, J. H. Buckley, V. Bugaev, A. Cesarini, L. Ciupik, M. P. Connolly, W. Cui, J. Dumm, M. Errando, A. Falcone, S. Federici, Q. Feng, J. P. Finley, P. Fortin, L. Fortson, A. Furniss, N. Galante, L. Gerard, G. H. Gillanders, S. Griffin, J. Grube, G. Gyuk, D. Hanna, J. Holder, G. Hughes, T. B. Humensky, P. Kaaret, M. Kertzman, Y. Khassen, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, A. S. Madhavan, G. Maier, P. Majumdar, S. Mcarthur, A. Mccann, P. Moriarty, R. Mukherjee, D. Nieto, A. O’Faolain De Bhroithe, P. T. Reynolds, Et Al

Physical Sciences Publications

We report on VERITAS observations of the BL Lac object B2 1215+30 between 2008 and 2012. During this period, the source was detected at very high energies (VHEs; E > 100 GeV) by VERITAS with a significance of 8.9σ and showed clear variability on timescales larger than months. In 2011, the source was found to be in a relatively bright state and a power-law fit to the differential photon spectrum yields a spectral index of 3.6 ± 0.4stat ± 0.3syst with an integral flux above 200 GeV of (8.0 ± 0.9stat ± 3.2syst) × 10−12 cm−2 s−1. No short term variability …

Molecular Hydrogen Regulated Star Formation In Cosmological Smoothed Particle Hydrodynamics Simulations, Robert Thompson, Kentaro Nagamine, Jason Jaacks, Jun-Hwan Choi

Physics and Astronomy Faculty Publications

Some observations have shown that star formation (SF) correlates tightly with the presence of molecular hydrogen (H₂); therefore, it is important to investigate its implication on galaxy formation in a cosmological context. In the present work, we implement a sub-grid model (hereafter H₂-SF model) that tracks the H₂ mass fraction within our cosmological smoothed particle hydrodynamics code GADGET-3 by using an equilibrium analytic model of Krumholz et al. This model allows us to regulate the SF in our simulation by the local abundance of H₂ rather than the total cold gas density, which naturally …

Dose Dependent Effects Of Caffeine On Cognitive Performance And Neuronal Activation, Stephan Albrecht, Helen Morris, Michelle Vieyra

Journal of the South Carolina Academy of Science

Many students assume that the more caffeine you drink, the better your cognitive performance. Over-consumption of caffeine has many negative effects, so if there are no dose related cognitive benefits to large amounts of caffeine, then college students should limit their intake. This study looked at whether ingesting a medium dose (200 mg) versus a lower dose (100 mg) of caffeine improved short term memory as measured by Flanker and n-back tests, compared to a control group. In addition, we looked at whether larger doses of caffeine produced a difference in neuronal activation during these tests as measured by functional …

Fourier Analysis Of Phase Resetting Curves Of Neural Oscillators, Robert A. Raidt, Sorinel A. Oprisan

Journal of the South Carolina Academy of Science

We investigated the impact of changes in biologically relevant control parameters, such as the shape of an external perturbation or the conductance values of an individual model neuron, on the shape of the phase resetting curve (PRC) of that neuron. For that purpose, PRCs were generated for groups of Morris-Lecar (ML) model neurons with different conductance values but similar firing periods (within 0.005ms) using external rectangular, triangular, or trapezoidal perturbations of varying areas. These PRCs were numerically described and analyzed as a series of coefficient values using a Fourier Discrete Sine Transform (DST). We found that changes in the shape …

Supernova Neutrino Nucleosynthesis Of Light Elements With Neutrino Oscillations, Takashi Yoshida, Toshitaka Kajino, Hidekazu Yokomakura, Keiichi Kimura, Akira Takamura, Dieter H. Hartmann

Publications

Light element synthesis in supernovae through neutrino-nucleus interactions, i.e., the ν-process, is affected by neutrino oscillations in the supernova environment. There is a resonance of 13-mixing in the O/C layer, which increases the rates of charged-current ν-process reactions in the outer He-rich layer. The yields of 7Li and 11B increase by about a factor of 1.9 and 1.3, respectively, for a normal mass hierarchy and an adiabatic 13-mixing resonance, compared to those without neutrino oscillations. In the case of an inverted mass hierarchy and a non-adiabatic 13-mixing resonance, the increase in the 7Li and 11B yields is much smaller. Observations …

Atomic Data For S Ii—Toward Better Diagnostics Of Chemical Evolution In High-Redshift Galaxies, Romas Kisielius, Varsha P. Kulkarni, Gary J. Ferland, Pavel Bogdanovich, Matt L. Lykins

Physics and Astronomy Faculty Publications

Absorption-line spectroscopy is a powerful tool used to estimate element abundances in both the nearby and distant universe. The accuracy of the abundances thus derived is naturally limited by the accuracy of the atomic data assumed for the spectral lines. We have recently started a project to perform new extensive atomic data calculations used for optical/UV spectral lines in the plasma modeling code Cloudy using state of the art quantal calculations. Here, we demonstrate our approach by focussing on S II, an ion used to estimate metallicities for Milky Way interstellar clouds as well as distant damped Lyman-alpha (DLA) and …

Sensitivity Curves For Searches For Gravitational-Wave Backgrounds, E. H. Thrane, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

We propose a graphical representation of detector sensitivity curves for stochastic gravitational-wave backgrounds that takes into account the increase in sensitivity that comes from integrating over frequency in addition to integrating over time. This method is valid for backgrounds that have a power-law spectrum in the analysis band. We call these graphs “power-law integrated curves.” For simplicity, we consider cross-correlation searches for unpolarized and isotropic stochastic backgrounds using two or more detectors. We apply our method to construct power-law integrated sensitivity curves for second-generation ground-based detectors such as Advanced LIGO, space-based detectors such as LISA and the Big Bang Observer, …

Development And Validation Of An Automated Directivity Acquisition System Used In The Acquisition, Processing, And Presentation Of The Acoustic Far-Field Directivity Of Musical Instruments In An Anechoic Space, Nicholas J. Eyring

Theses and Dissertations

A high spatial resolution acoustic directivity acquisition system (ADAS) has been developed to acquire anechoic measurements of the far field radiation of musical instruments that are either remote controlled or played by musicians. Building upon work performed by the BYU Acoustic Research Group in the characterization of loudspeaker directivity, one can rotate a musical instrument with sequential azimuthal angle increments under a fixed semicircular array of microphones while recording repeated notes or sequences of notes. This results in highly detailed and instructive directivity data presented in the form of high-resolution balloon plots. The directivity data and corresponding balloon plots may …

Uncovering The Deeply Embedded Active Galactic Nucleus Activity In The Nuclear Regions Of The Interacting Galaxy Arp 299, A Alonso-Herrero, Eric S. Perlman

Aerospace, Physics, and Space Science Faculty Publications

We present mid-infrared (MIR) 8-13 μm spectroscopy of the nuclear regions of the interacting galaxy Arp 299 (IC 694+NGC 3690) obtained with CanariCam (CC) on the 10.4 m Gran Telescopio Canarias (GTC). The high angular resolution (∼0.″3-0.″6) of the data allows us to probe nuclear physical scales between 60 and 120 pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded active galactic nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC 3690/Arp 299-B1 can be explained as emission from AGN-heated dust in …

The Progenitors Of The Compact Early-Type Galaxies At High Redshift, Christina C. Williams, Mauro Giavalisco, Paolo Cassata, Elena Tundo, Tommy Wiklind, Yicheng Guo, Bomee Lee, Guillermo Barro, Stijn Wuyts, Eric F. Bell, Christopher J. Conselice, Avishai Dekel, Sandra M. Faber, Henry C. Ferguson, Norman A. Grogin, Nimish Hathi, Kuang-Han Huang, Dalibor D. Kocevski, Anton M. Koekemoer, David C. Koo, Swara Ravindranath, Sarah Salimbeni

Physics and Astronomy Faculty Publications

We use GOODS and CANDELS images to identify progenitors of massive (M > 10¹⁰ M _☉) compact early-type galaxies (ETGs) at z ~ 1.6. Because merging and accretion increase the size of the stellar component of galaxies, if the progenitors are among known star-forming galaxies, these must be compact themselves. We select candidate progenitors among compact Lyman-break galaxies at z ~ 3 on the basis of their mass, star-formation rate (SFR), and central stellar density, and we find that these account for a large fraction of, and possibly all, compact ETGs at z ~ 1.6. We find that …

The Unexpectedly Bright Comet C/2012 F6 (Lemmon) Unveiled At Near-Infrared Wavelengths, Lucas Paganini, Michael Disanti, Michael Mumma, Geronimo Villanueva, Boncho Bonev, Jacqueline Keane, Erika Gibb, Hermann Boehnhardt, Karen Meech

Physics Faculty Works

We acquired near-infrared spectra of the Oort cloud comet C/2012 F6 (Lemmon) at three different heliocentric distances (R h) during the comet's 2013 perihelion passage, providing a comprehensive measure of the outgassing behavior of parent volatiles and cosmogonic indicators. Our observations were performed pre-perihelion at R h = 1.2 AU with CRIRES (on 2013 February 2 and 4), and post-perihelion at R h = 0.75 AU with CSHELL (on March 31 and April 1) and R h = 1.74 AU with NIRSPEC (on June 20). We detected 10 volatile species (H2O, OH* prompt emission, C2H6, CH3OH, H2CO, HCN, CO, CH4, …

The Unexpectedly Bright Comet C/2012 F6 (Lemmon) Unveiled At Near-Infrared Wavelengths, Lucas Paganini, Michael A. Disanti, Michael J. Mumma, Geronimo L. Villanueva, Boncho P. Bonev, Jacqueline V. Keane, Erika L. Gibb, Hermann Boehnhardt, Karen J. Meech

Erika Gibb

The Halo Occupation Distribution Of X-Ray-Bright Active Galactic Nuclei: A Comparison With Luminous Quasars, Jonathan Richardson, Suchetana Chatterjee, Zheng Zheng, Adam D. Myers, Ryan Hickox

Dartmouth Scholarship

We perform halo occupation distribution (HOD) modeling of the projected two-point correlation function (2PCF) of high-redshift (z~1.2) X-ray-bright active galactic nuclei (AGN) in the XMM-COSMOS field measured by Allevato et al. The HOD parameterization is based on low-luminosity AGN in cosmological simulations. At the median redshift of z~1.2, we derive a median mass of (1.02+0.21/-0.23)x10^{13} Msun/h for halos hosting central AGN and an upper limit of ~10% on the AGN satellite fraction. Our modeling results indicate (at the 2.5-sigma level) that X-ray AGN reside in more massive halos compared to more bolometrically luminous, optically-selected quasars at similar redshift. The modeling …

Magnetic Inhibition Of Convection And The Fundamental Properties Of Low-Mass Stars. I. Stars With A Radiative Core, Gregory A. Feiden, Brian Chaboyer

Dartmouth Scholarship

Magnetic fields are hypothesized to inflate the radii of low-mass stars—defined as less massive than 0.8 M _☉—in detached eclipsing binaries (DEBs). We investigate this hypothesis using the recently introduced magnetic Dartmouth stellar evolution code. In particular, we focus on stars thought to have a radiative core and convective outer envelope by studying in detail three individual DEBs: UV Psc, YY Gem, and CU Cnc. Our results suggest that the stabilization of thermal convection by a magnetic field is a plausible explanation for the observed model-radius discrepancies. However, surface magnetic field strengths required by the models are significantly stronger …

Veritas Observations Of The Microquasar Cygnus X-3, P. T. Reynolds, Et Al

Physical Sciences Publications

We report results from TeV gamma-ray observations of the microquasar Cygnus X-3. The observations were made with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) over a time period from 2007 June 11 to 2011 November 28. VERITAS is most sensitive to gamma rays at energies between 85 GeV and 30 TeV. The effective exposure time amounts to a total of about 44 hr, with the observations covering six distinct radio/X-ray states of the object. No significant TeV gamma-ray emission was detected in any of the states, nor with all observations combined. The lack of a positive signal, especially …

Effects Of External Radiation Fields On Line Emission—Application To Star-Forming Regions, Marios Chatzikos, Gary J. Ferland, R. J. R. Williams, Ryan Porter, P. A. M. Vanhoof

Physics and Astronomy Faculty Publications

A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous …

Time Variation Of The Broad Hβ And Hα Emission Lines In Active Galactic Nuclei, Bryan R. Scott

Physics

High-quality Keck/LRIS long-slit spectra for a sample of 97 active galaxies selected from the Sloan Digital Sky Survey (redshift between 0.02 & 0.1; Black Hole Mass approximately 10⁷ Solar Masses) were obtained between January 2009 and March 2010 in order to study the black hole (BH) mass scaling relation in the local universe. Typically, the width of the broad Hβ emission line is used to measure the mass of the black hole (MBH). However, signs of variability in the emission line profile are seen for eight objects: While broad Hβ emission lines had previously been observed in spectra from …

Interpreting Near Infrared Hydrogen Line Ratios In T Tauri Stars, Suzan Edwards

Astronomy: Faculty Publications

In accreting young stars, one of the prominent spectral features in the near-infrared is the Paschen and Brackett series in emission. We examine hydrogen line ratios for 16 classical T Tauri stars from SpeX spectra and assess the trends with veiling and accretion. The observed line ratios are compared with two theoretical models for line formation: (1) Baker & Menzel’s Case B for radiative ionization and recombination and (2) a set of local line excitation calculations designed to replicate the conditions in T Tauri winds and magnetic accretion columns (KF). While the comparison between Case B and observed line ratios …

Magneto-Transport Characteristics Of A 2d Electron System Driven To Negative Magneto-Conductivity By Microwave Photoexcitation, Ramesh G. Mani, Annika Kriisa

Physics and Astronomy Faculty Publications

Negative diagonal magneto-conductivity/resistivity is a spectacular- and thought provoking-property of driven, far-from-equilibrium, low dimensional electronic systems. The physical response of this exotic electronic state is not yet fully understood since it is rarely encountered in experiment. The microwave-radiation-induced zero-resistance state in the high mobility GaAs/AlGaAs 2D electron system is believed to be an example where negative magneto-conductivity/resistivity is responsible for the observed phenomena. Here, we examine the magneto-transport characteristics of this negative conductivity/ resistivity state in the microwave photo-excited two-dimensional electron system (2DES) through a numerical solution of the associated boundary value problem. The results suggest, surprisingly, that a bare …

Constraints On A Second Planet In The Wasp-3 System, G. Maciejewski, A. Niedzielski, A. Wolszczan, G. Nowak, R. Neuhäuser, J. N. Winn, B. Deka, M. Adamów, M. Górecka, M. Fernández, F. J. Aceituno, J. Ohlert, R. Errmann, M. Seeliger, D. P. Dimitrov, D. W. Latham, G. A. Esquerdo, L. Mcknight, M. J. Holman, Eric L.N. Jensen, U. Kramm, T. Pribulla, S. Raetz, T. O.B. Schmidt, C. Ginski, S. Mottola, S. Hellmich, C. Adam, H. Gilbert, M. Mugrauer, G. Saral, V. Popov, M. Raetz

Physics & Astronomy Faculty Works

There have been previous hints that the transiting planet WASP-3b is accompanied by a second planet in a nearby orbit, based on small deviations from strict periodicity of the observed transits. Here we present 17 precise radial velocity (RV) measurements and 32 transit light curves that were acquired between 2009 and 2011. These data were used to refine the parameters of the host star and transiting planet. This has resulted in reduced uncertainties for the radii and masses of the star and planet. The RV data and the transit times show no evidence for an additional planet in the system. …

Chemical Evolution Of The Neutron-Rich Iron-Group Isotopes And Implications For The Formation Of Fun Cais, Tianhong Yu

All Dissertations

Calcium-aluminum-rich inclusions (CAIs) are millimeter-sized refractory objects found in primitive meteorites. CAIs are considered as some of the first solids to form in the solar system, because they are refractory. FUN CAIs, those with Fractionated and Unknown Nuclear effects, are a small subset of CAIs. These FUN CAIs show correlated excesses and deficits in the neutron-rich iron-group isotopes such as ⁴⁸ Ca and ⁵⁰ Ti which regular CAIs do not. Interestingly, these isotopes are most likely produced infrequently but in huge quantities in a rare class of thermonuclear (Type Ia) supernovae. I propose that the isotopic effects in the neutron-rich …

Infrared Spectra Analysis Of Thermally Altered Iron Phyllosilicates And The Implications For Mars, William Thomas Bryan

Graduate Theses and Dissertations

This study looks at two iron-rich phyllosilicates, which may be present on Mars. The minerals, greenalite and hisingerite, are rich in iron-II and iron-III, respectively. Small samples (~0.40 grams) of each mineral were crushed and heated in a Lindberg Tube Oven for approximately twenty-four hours at temperatures selected to mimic lava flows and impact events. Following heating, each sample was placed in a Fourier Transform Infrared (FT-IR) spectrometer to collect the near- and mid-infrared spectra. The spectra allowed for these terrestrial analogs to be analyzed with regards to how their structure breaks down with increasing temperature. The samples' colors were …

Solar Energy Conversion And Control Using Organic Photovoltaic Cells, Kurt Wade Woods

Masters Theses & Specialist Projects

Organic photovoltaic (OPV) cells are advanced, newly emerging technologies that are lightweight, mechanically flexible devices with highthroughput processes from low cost material in a variety of colors. Rathnayake et al. of Western Kentucky University have developed a nanostructure-based OPV cell. Presented in this thesis is a model and simulation of a generalized PV powered system that can predict the performance of solar arrays in various environmental conditions. The simulation has been carried out in Matlab/Simulink, and upon entering the cell’s parameters, it provides key electrical characteristics such as the cell’s I-V curve and efficiency information. The total system that is …

Bacterially-Mediated Formation Of Rock Coatings In Kärkevagge, Swedish Lapland: A Mineralogical And Micro-Environmental Analog For Mars, Cassandra L. Marnocha

Graduate Theses and Dissertations

The search for past or present life on Mars is, for now, limited to surface environments. An often neglected surface environment that could have served as an abode for life and could presently preserve evidence of that life is that of rock coatings. Rock coatings are mineral accretions on rock surfaces. On Earth, they are widespread and occur with considerable chemical diversity. There is growing evidence for a biotic role in their formation on Earth, particularly with respect to rock varnish. As a result, rock varnish has become a target of astrobiological interest on Mars, where varnish-like coatings have been …

An Integrated Multidisciplinary Nanoscience Concentration Certificate Program For Stem Education, Karen S. Martirosyan, Mikhail M. Bouniaev, Malik Rakhmanov, Ahmed Touhami, Nazmul Islam, Davood Askari, Tarek Trad, Dmitri Litvinov, Sergey E. Lyshevski

Physics and Astronomy Faculty Publications and Presentations

Integration of nanoscience and nanotechnology curricula into the College of Science, Mathematics, and Technology (CSMT) at the University of Texas at Brownsville (UTB) is reported. The rationale for the established multidisciplinary Nanoscience Concentration Certificate Program (NCCP) is to: (i) develop nanotechnology-relevant courses within a comprehensive Science, Engineering and Technology curriculum, and, to offer students an opportunity to graduate with a certificate in nanoscience and nanotechnology; (ii) to contribute to students' success in achieving student outcomes across all college's majors, and, improve the breath, depth and quality of science, technology, engineering and mathematics (STEM) graduates' education; (iii) through NCCP, recruit certificate- …

Detection Of Pulsar Beams Deflected By The Black Hole In Sgr A*: Effects Of Black Hole Spin, Sourabh Nampalliwar, Richard H. Price, Teviet Creighton, Fredrick A. Jenet

Physics and Astronomy Faculty Publications and Presentations

Some Galactic models predict a significant population of radio pulsars close to the Galactic center. Beams from these pulsars could be strongly deflected by the supermassive black hole (SMBH) believed to reside at the Galactic center and as a result reach Earth. Earlier work assuming a Schwarzschild SMBH gave marginal chances of observing this exotic phenomenon with current telescopes and good chances with future telescopes. Here we study whether those estimates are significantly affected by SMBH spin. We find that spin effects make a negligible difference in detectability, but the pattern of pulse arrival times is clearly affected. In particular, …