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Photospheric Radius Evolution Of Homologous Explosions, Liang-Duan Liu, Bing Zhang, Ling-Jun Wang, Zi-Gao Dai 2018 Nanjing University; University of Nevada, Las Vegas

Photospheric Radius Evolution Of Homologous Explosions, Liang-Duan Liu, Bing Zhang, Ling-Jun Wang, Zi-Gao Dai

Physics & Astronomy Faculty Publications

Recent wide-field surveys discovered new types of peculiar optical transients that showed diverse behaviors of the evolution of photospheric properties. We develop a general theory of homologous explosions with constant opacity, paying special attention to the evolution of the photospheric radius R ph. We find that regardless of the density distribution profile, R ph always increases early on and decreases at late times. This result does not depend on the radiation and cooling processes inside the ejecta. The general rising/falling behavior of R ph can be used to quickly diagnose whether the source originates from a supernova-like explosion. The ...


Diffusion And Concentration Of Solids In The Dead Zone Of A Protoplanetary Disk, Chao-Chin Yang, Mordecai-Mark Mac Low, Anders Johansen 2018 Lund University; University of Nevada, Las Vegas

Diffusion And Concentration Of Solids In The Dead Zone Of A Protoplanetary Disk, Chao-Chin Yang, Mordecai-Mark Mac Low, Anders Johansen

Physics & Astronomy Faculty Publications

The streaming instability is a promising mechanism to drive the formation of planetesimals in protoplanetary disks. To trigger this process, it has been argued that sedimentation of solids onto the mid-plane needs to be efficient, and therefore that a quiescent gaseous environment is required. It is often suggested that dead-zone or disk-wind structure created by non-ideal magnetohydrodynamical (MHD) effects meets this requirement. However, simulations have shown that the mid-plane of a dead zone is not completely quiescent. In order to examine the concentration of solids in such an environment, we use the local-shearing-box approximation to simulate a particlegas system with ...


Bunching Coherent Curvature Radiation In Three-Dimensional Magnetic Field Geometry: Application To Pulsars And Fast Radio Bursts, Yuan-Pei Yang, Bing Zhang 2018 Peking University; Chinese Academy of Sciences; KIAA-CAS Fellow

Bunching Coherent Curvature Radiation In Three-Dimensional Magnetic Field Geometry: Application To Pulsars And Fast Radio Bursts, Yuan-Pei Yang, Bing Zhang

Physics & Astronomy Faculty Publications

The extremely high brightness temperatures of pulsars and fast radio bursts (FRBs) require their radiation mechanisms to be coherent. Coherent curvature radiation from bunches has been long discussed as the mechanism for radio pulsars and recently for FRBs. Assuming that bunches are already generated in pulsar magnetospheres, we calculate the spectrum of coherent curvature radiation under a three-dimensional magnetic field geometry. Different from previous works assuming parallel trajectories and a monoenergetic energy distribution of electrons, we consider a bunch characterized by its length, curvature radius of the trajectory family, bunch opening angle, and electron energy distribution. We find that the ...


Reason In Motion, Luke Francis 2018 Embry-Riddle Aeronautical University

Reason In Motion, Luke Francis

Student Works

This essay will explain the historical models of the solar system, which was the known universe for most of human history. There is far more to each model than simply positioning different celestial bodies at the center of the system, and the stories of the astronomers who derived the controversial theories are not discussed often enough. The creation of these theories is part of a much broader revolution in scientific thought and marked the start of a series of observational discoveries that would change the the philosophy of science for centuries to come.


Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters Ii: Ngc 5024, Ngc 5272, And Ngc 6352, Rachel Wagner-Kaiser, Ted von Hippel, David Stenning, Elliot Robinson, Ata Sarajedini, David van Dyk, Nathan Stein, William H. Jefferys 2018 University of Florida

Bayesian Analysis Of Two Stellar Populations In Galactic Globular Clusters Ii: Ngc 5024, Ngc 5272, And Ngc 6352, Rachel Wagner-Kaiser, Ted Von Hippel, David Stenning, Elliot Robinson, Ata Sarajedini, David Van Dyk, Nathan Stein, William H. Jefferys

Publications

We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival ACS Treasury observations of Galactic Globular Clusters to find and characterize two stellar populations in NGC 5024 (M53), NGC 5272 (M3), and NGC 6352. For these three clusters, both single and double-population analyses are used to determine a best fit isochrone(s). We employ a sophisticated Bayesian analysis technique to simultaneously fit the cluster parameters (age, distance, absorption, and metallicity) that characterize each cluster. For the two-population analysis, unique population level helium values are also fit to each distinct population of the cluster and the relative proportions of ...


Dance Of Two Supermassive Binary Black Holes, Karishma Bansal 2018 University of New Mexico

Dance Of Two Supermassive Binary Black Holes, Karishma Bansal

Shared Knowledge Conference

Black holes exist in a various range of masses ranging from stellar mass (~ 10 Solar Mass) to Supermassive black holes (SMBHs, million to billion Solar Mass). It is expected that as the separation between the black holes decreases, emission of gravitational waves will grow stronger, which makes binary black holes one of the most promising sources for gravitational radiation detection. Gravitational waves from merging stellar-mass black holes have recently been discovered by LIGO; however, we are yet to detect them from binary SMBHs. These massive black holes reside at the heart of most of the galaxies and when two such ...


Nonthermal Dark Matter From Early Matter Domination, Jacek Ksawery Osinski 2018 University of New Mexico

Nonthermal Dark Matter From Early Matter Domination, Jacek Ksawery Osinski

Shared Knowledge Conference

Dark matter (DM) production in the early universe traditionally assumes a standard thermal history where the universe is in a radiation-dominated phase after the end of inflation until matter-radiation equality. However, the presence of additional scalar fields (which is a generic prediction of explicit string constructions) can lead to an epoch of early matter domination (EMD) that ends before the onset of big bang nucleosynthesis. Such an EMD phase has important cosmological consequences and renders thermal production of DM irrelevant. We present three scenarios for DM production involving an era of EMD: evaporation of primordial black holes into DM, DM ...


The Undeniable Attraction Of Lunar Swirls, Cierra Waller, Dhananjay Ravat 2018 University of Kentucky

The Undeniable Attraction Of Lunar Swirls, Cierra Waller, Dhananjay Ravat

Posters-at-the-Capitol

Lunar swirls are complex patterns on the Moon with distinct brightness signatures and magnetic characteristics. Current research has suggested that the formation of lunar swirls relies on local magnetic fields to shield impinging solar wind, based on a shift in electromagnetic wavelength peaks related to solar radiation and space weathering. Our research combined recent models and methods to characterize these anomalies at the surface of the Moon, exploring the effects of field strength and position. We have produced a high resolution map of a famous swirl named Reiner Gamma using magnetic dipole modeling. These maps and models are considered when ...


The Shape Of The Orbit In Flrw Spacetimes, David Garfinkle, Lawrence R. Mead, H.I. Ringermacher 2018 Oakland University

The Shape Of The Orbit In Flrw Spacetimes, David Garfinkle, Lawrence R. Mead, H.I. Ringermacher

Faculty Publications

The shape of the orbit of a free particle is examined in Friedmann-Lemaître-Robertson-Walker (FLRW) cosmologies. The spatial projection of the orbit is time-independent and has a simple geometric description. We relate this description to the expression in terms of standard FLRW coordinates.


5 - Irregularities In Young Stellar Models: Are Starspots To Blame?, Jessica Hamilton 2018 University of North Georgia

5 - Irregularities In Young Stellar Models: Are Starspots To Blame?, Jessica Hamilton

Georgia Undergraduate Research Conference (GURC)

Starspots are dark areas on a star’s surface formed by intense magnetic fields that actively suppress the flow of energy, causing the area to become cooler and darker than its surroundings. Starspots threaten a star’s equilibrium because they prevent energy from leaving the star, causing a buildup of pressure. The prevailing assumption is that increased pressure will cause the star to inflate, producing a cooler and larger star. For this reason, starspots have been proposed to explain why some stars appear cooler and larger than we expect. This requires energy blocked by a spot to be trapped deep ...


4 - A Flexible Model For Investigating The Properties Of Starspots: Comparison Of Model Predictions To Observed Data, Amanda Ash 2018 University of North Georgia

4 - A Flexible Model For Investigating The Properties Of Starspots: Comparison Of Model Predictions To Observed Data, Amanda Ash

Georgia Undergraduate Research Conference (GURC)

Accurate age estimates provide a wealth of information about the mechanisms of different astrophysical phenomenon. However, current methods of applying stellar evolution models to obtain these estimates has proven to be flawed, with models having little consistency. It has been speculated the source of this inconsistency may arise from deviations in stellar properties due to the presence of dark blemishes, starspots, present on young cool stars (Feiden, 2016). Using predictions of expected properties from the flexible starspot model to observed properties of various open clusters, we aim to define what starspot properties bring model predictions into agreement with observed data ...


Interaction Between Gravitational Radiation And Electromagnetic Radiation, Preston Jones, Douglas Singleton 2018 Embry-Riddle Aeronautical University

Interaction Between Gravitational Radiation And Electromagnetic Radiation, Preston Jones, Douglas Singleton

Publications

In this review paper we investigate the connection between gravity and electromagnetism from Faraday to the present day. The particular focus is on the connection between gravitational and electromagnetic radiation. We discuss electromagnetic radiation produced when a gravitational wave passes through a magnetic field. We then discuss the interaction of electromagnetic radiation with gravitational waves via Feynman diagrams of the process graviton + graviton → photon + photon. Finally we review recent work on the vacuum production of counterpart electromagnetic radiation by gravitational waves.


Fast Radio Burst Energetics And Detectability From High Redshifts, Bing Zhang 2018 University of Nevada, Las Vegas

Fast Radio Burst Energetics And Detectability From High Redshifts, Bing Zhang

Physics & Astronomy Faculty Publications

We estimate the upper limit redshifts of known fast radio bursts (FRBs) using the dispersion measure (DM)-redshift (z) relation and derive the upper limit peak luminosity L p and energy E of FRBs within the observational band. The average z upper limits range from 0.17 to 3.10, the average L p upper limits range from 1.24 × 1042 erg s−1 to 7.80 × 1044 erg s−1, and the average E upper limits range from 6.91 × 1039 erg to 1.94 × 1042 erg. FRB 160102 with DM = 2596.1 ± 0.3 pc cm−3 likely ...


The Kelt Follow-Up Network And Transit False-Positive Catalog: Pre-Vetted False Positives For Tess, K. A. Collins, K. I. Collins, J. Pepper, J. Labadie-Bartz, K. G. Stassun, B. S. Gaudi, D. Bayliss, J. Bento, K. D. Colón, D. Feliz, D. James, M. C. Johnson, R. B. Kuhn, M. B. Lund, M. T. Penny, J. E. Rodriguez, R. J. Siverd, D. J. Stevens, X. Yao, G. Zhou, M. Akshay, G. F. Aldi, C. Ashcraft, S. Awiphan, Ö. Baştürk, D. Baker, T. G. Beatty, P. Benni, P. Berlind, G. B. Berriman, Z. Berta-Thompson, A. Bieryla, V. Bozza, S. C. Novati, M. L. Calkins, J. M. Cann, D. R. Ciardi, W. D. Cochran, David H. Cohen, D. Conti, J. R. Crepp, I. A. Curtis, G. D'Ago, K. A. Diazeguigure, C. D. Dressing, F. Dubois, E. Ellington, T. G. Ellis, G. A. Esquerdo, P. Evans, A. Friedli, A. Fukui, B. J. Fulton, E. J. Gonzales, J. C. Good, J. Gregorio, T. Gumusayak, D. A. Hancock, C. K. Harada, R. Hart, E. G. Hintz, H. Jang-Condell, E. J. Jeffery, Eric L.N. Jensen, E. Jofré, M. D. Joner, A. Kar, D. H. Kasper, B. Keten, J. F. Kielkopf, S. Komonjinda, C. Kotnik, D. W. Latham, J. Leuquire, T. R. Lewis, L. Logie, S. J. Lowther, P. J. Macqueen, T. J. Martin, D. Mawet, K. K. Mcleod, G. Murawski, N. Narita, J. Nordhausen, T. E. Oberst, C. Odden, P. A. Panka, R. Petrucci, P. Plavchan, S. N. Quinn, S. Rau, P. A. Reed, H. Relles, J. P. Renaud, G. Scarpetta, R. L. Sorber, A. D. Spencer, M. Spencer, D. C. Stephens, C. Stockdale, T.-G. Tan, M. Trueblood, P. Trueblood, S. Vanaverbeke, S. Villanueva Jr., E. M. Warner, M. L. West, S. Yalçınkaya, R. Yeigh, R. Zambelli 2018 Swarthmore College

The Kelt Follow-Up Network And Transit False-Positive Catalog: Pre-Vetted False Positives For Tess, K. A. Collins, K. I. Collins, J. Pepper, J. Labadie-Bartz, K. G. Stassun, B. S. Gaudi, D. Bayliss, J. Bento, K. D. Colón, D. Feliz, D. James, M. C. Johnson, R. B. Kuhn, M. B. Lund, M. T. Penny, J. E. Rodriguez, R. J. Siverd, D. J. Stevens, X. Yao, G. Zhou, M. Akshay, G. F. Aldi, C. Ashcraft, S. Awiphan, Ö. Baştürk, D. Baker, T. G. Beatty, P. Benni, P. Berlind, G. B. Berriman, Z. Berta-Thompson, A. Bieryla, V. Bozza, S. C. Novati, M. L. Calkins, J. M. Cann, D. R. Ciardi, W. D. Cochran, David H. Cohen, D. Conti, J. R. Crepp, I. A. Curtis, G. D'Ago, K. A. Diazeguigure, C. D. Dressing, F. Dubois, E. Ellington, T. G. Ellis, G. A. Esquerdo, P. Evans, A. Friedli, A. Fukui, B. J. Fulton, E. J. Gonzales, J. C. Good, J. Gregorio, T. Gumusayak, D. A. Hancock, C. K. Harada, R. Hart, E. G. Hintz, H. Jang-Condell, E. J. Jeffery, Eric L.N. Jensen, E. Jofré, M. D. Joner, A. Kar, D. H. Kasper, B. Keten, J. F. Kielkopf, S. Komonjinda, C. Kotnik, D. W. Latham, J. Leuquire, T. R. Lewis, L. Logie, S. J. Lowther, P. J. Macqueen, T. J. Martin, D. Mawet, K. K. Mcleod, G. Murawski, N. Narita, J. Nordhausen, T. E. Oberst, C. Odden, P. A. Panka, R. Petrucci, P. Plavchan, S. N. Quinn, S. Rau, P. A. Reed, H. Relles, J. P. Renaud, G. Scarpetta, R. L. Sorber, A. D. Spencer, M. Spencer, D. C. Stephens, C. Stockdale, T.-G. Tan, M. Trueblood, P. Trueblood, S. Vanaverbeke, S. Villanueva Jr., E. M. Warner, M. L. West, S. Yalçınkaya, R. Yeigh, R. Zambelli

Physics & Astronomy Faculty Works

The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey of transiting planets orbiting bright stars for over 10 years. The KELT images have a pixel scale of ~23'' pixel⁻¹—very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS)—as well as a large point-spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3'. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with ...


Search For A Dark Photon In Electroproduced E + E − Pairs With The Heavy Photon Search Experiment At Jlab, P. H. Adrian, N. A. Baltzell, M. Battaglieri, M. Bondí, S. Boyarinov, S. Bueltmann, G. Kalicy, H. Szumila-Vance, L. B. Weinstein, Heavy Photon Search Collaboration 2018 Old Dominion University

Search For A Dark Photon In Electroproduced E + E − Pairs With The Heavy Photon Search Experiment At Jlab, P. H. Adrian, N. A. Baltzell, M. Battaglieri, M. Bondí, S. Boyarinov, S. Bueltmann, G. Kalicy, H. Szumila-Vance, L. B. Weinstein, Heavy Photon Search Collaboration

Physics Faculty Publications

The Heavy Photon Search experiment took its first data in a 2015 engineering run using a 1.056 GeV, 50 nA electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility, searching for a prompt, electroproduced dark photon with a mass between 19 and 81  MeV/c2. A search for a resonance in the e+e invariant mass distribution, using 1.7 days (1170  nb−1) of data, showed no evidence of dark photon decays above the large QED background, confirming earlier searches and demonstrating the full functionality of the experiment. Upper limits on the square of ...


P-43 Doing Astronomy With Gravitational Waves, Tiffany Summerscales 2018 Andrews University

P-43 Doing Astronomy With Gravitational Waves, Tiffany Summerscales

Celebration of Research and Creative Scholarship

With the first detection of gravitational waves on September 14, 2015, the new era of gravitational wave astronomy began. Gravitational wave detections, along with observations made by optical telescopes, have given us new information about the universe. This includes new estimates of the numbers of black holes in the universe and their properties, as well as confirming theories about the sources of some gamma ray bursts and how those sources produce heavy elements.


Observation Of High-Energy Gamma-Rays With The Calorimetric Electron Telescope (Calet) On-Board The International Space Station, Nicholas Wade Cannady 2018 Louisiana State University and Agricultural and Mechanical College

Observation Of High-Energy Gamma-Rays With The Calorimetric Electron Telescope (Calet) On-Board The International Space Station, Nicholas Wade Cannady

LSU Doctoral Dissertations

The CALorimetric Electron Telescope (CALET) is a multi-instrument high-energy astrophysics observatory deployed to the International Space Station (ISS) in August 2015. The primary instrument is the calorimeter (CAL), which is intended for measurement of the cosmic ray electron flux in the energy range 10 GeV - 20 TeV. The CAL is also sensitive to gamma-rays in the energy range 1 GeV - 10 TeV and protons and nuclei up to PeV energies. Also present on the CALET payload are an Advanced Stellar Compass (ASC) for the fine determination of the pointing direction and the CALET Gamma-ray Burst Monitor (CGBM) for the observation ...


Gravity's Light In The Shadow Of The Moon, Andri Gretarsson, Preston Jones, Douglas Singleton 2018 Embry-Riddle Aeronautical University

Gravity's Light In The Shadow Of The Moon, Andri Gretarsson, Preston Jones, Douglas Singleton

Publications

In this essay we look at the possibility of vacuum production of very low frequency electromagnetic radiation from a gravitational wave background (i.e. gravity's light). We also propose that this counterpart electromagnetic radiation should be detectable by a lunar orbiting satellite which is periodically occulted by the Moon (i.e., in the shadow of the Moon). For concreteness we consider the possibility of detection of both the gravitational wave and hypothesized electromagnetic radiation counterpart from the supernova core collapse of Betelgeuse


Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen 2018 Lund University

Streaming Instability Of Multiple Particle Species In Protoplanetary Disks, Noemi Schaffer, Chao-Chin Yang, Anders Johansen

Physics & Astronomy Faculty Publications

The radial drift and diffusion of dust particles in protoplanetary disks affect both the opacity and temperature of such disks, as well as the location and timing of planetesimal formation. In this paper, we present results of numerical simulations of particle-gas dynamics in protoplanetary disks that include dust grains with various size distributions. We have considered three scenarios in terms of particle size ranges, one where the Stokes number τs = 10−1−100, one where τs = 10−4−10−1, and finally one where τs= 10−3−100. Moreover, we considered both discrete and continuous distributions in particle size. In ...


A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen 2018 Stanford Univesity

A Bayesian Framework For Exoplanet Direct Detection And Non-Detection, Jean-Baptiste Ruffio, Dimitri Mawet, Ian Czekala, Bruce Macintosh, Robert J. De Rosa, Garreth Ruane, Michael Bottom, Laurent Pueyo, Jason J. Wang, Lea Hirsch, Zhaohuan Zhu, Eric L. Nielsen

Physics & Astronomy Faculty Publications

Rigorously quantifying the information in high-contrast imaging data is important for informing follow-up strategies to confirm the substellar nature of a point source, constraining theoretical models of planet–disk interactions, and deriving planet occurrence rates. However, within the exoplanet direct imaging community, non-detections have almost exclusively been defined using a frequentist detection threshold (i.e., contrast curve) and associated completeness. This can lead to conceptual inconsistencies when included in a Bayesian framework. A Bayesian upper limit is such that the true value of a parameter lies below this limit with a certain probability. The associated probability is the integral of ...


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