Astrophysics and Astronomy Commons^™

Revealing The X-Ray Source In Iras 13224-3809 Through Flux-Dependent Reverberation Lags, E. Kara, A. C. Fabian, E. M. Cackett, G. Miniutti, P. Uttley

Physics and Astronomy Faculty Research Publications

IRAS 13224-3809 was observed in 2011 for 500 ks with the XMM-Newton observatory. We detect highly significant X-ray lags between soft (0.3-1 keV) and hard (1.2-5 keV) energies. The hard band lags the soft at low frequencies (i.e. hard lag), while the opposite (i.e. soft lag) is observed at high frequencies. In this paper, we study the lag during flaring and quiescent periods. We find that the frequency and absolute amplitude of the soft lag are different during high-flux and low-flux periods. During the low-flux intervals, the soft lag is detected at higher frequencies and with smaller amplitude. Assuming that …

Discovery Of Fe Kα X-Ray Reverberation Around The Black Holes In Mcg-5-23-16 And Ngc 7314, A. Zoghbi, C. Reynolds, E. M. Cackett, G. Miniutti, E. Kara, A. C. Fabian

Physics and Astronomy Faculty Research Publications

Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in active galactic nuclei. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe Kα line peaks, lags the bands at lower …

A Statistical Analysis Of Electromagnetic Ion Cyclotron (Emic) Waves And Their Correlation To The 11-Year Solar Cycle, Erik A. Lindgren

Honors Theses and Capstones

This thesis presents a statistical analysis of EMIC waves measured at Halley Research Station from 2008 through 2012. An introduction covering the origin of and theory behind EMIC waves is provided, along with a background covering previous statistical research regarding EMIC waves. Guidelines regarding EMIC wave definition and analysis are described along with examples of how they were used. The data shows an increase in the total number of EMIC waves as well as the number and percentage of EMIC waves with maximum frequency above 1 Hz during the 5-year period. The results suggest that the total number of EMIC …

Phys 491/891

Department of Physics and Astronomy: Syllabi

No abstract provided.

Using The Radial Velocity To Search For Orbiting Planets Around Mira, Emma Molden

Undergraduate Research Symposium 2013

We researched radio astronomical data from the star Omicron Ceti, more commonly known as Mira, to determine if there is evidence for orbiting planets. There is a variation in the silicon monoxide maser radial velocity of Mira that could have been due to the effect of orbiting planets. We analyzed the radial velocity data collected from Mira over the past forty years. The data were examined for periodicities. A periodicity refers to a repeating pattern within the data. Three possible frequencies were found. Each frequency within the star had the potential to be a pattern caused by an orbiting planet. …

Transport Of Solar Energetic Particles Accelerated By Icme Shocks: Reproducing The Reservoir Phenomenon, Gang Qin, Y Wang, Ming Zhang, Silvia Dalla

Aerospace, Physics, and Space Science Faculty Publications

In this work, gradual solar energetic particle (SEP) events observed by multiple spacecraft are investigated with model simulations. Based on a numerical solution of the Fokker-Planck focused transport equation including perpendicular diffusion of particles, we obtained the fluxes of SEPs accelerated by an interplanetary coronal mass ejection driven shock as it propagates outward through the three-dimensional Parker interplanetary magnetic field. The shock is treated as a moving source of energetic particles with an assumed particle distribution function. We look at the time profiles of particle flux as they are observed simultaneously by multiple spacecraft located at different locations. The dependence …

The Nature Of The H2-Emitting Gas In The Crab Nebula, C. T. Richardson, J. A. Baldwin, Gary J. Ferland, E. D. Loh, C. A. Kuehn, A. C. Fabian, Philippe Salomé

Physics and Astronomy Faculty Publications

Understanding how molecules and dust might have formed within a rapidly expanding young supernova remnant is important because of the obvious application to vigorous supernova activity at very high redshift. In previous papers, we have mapped the Crab nebula (the Crab) in a rotovibrational H₂emission line, and then measured the molecular excitation temperature for a few of the brighter H₂-emitting knots that we have found to be scattered throughout the Crab's filaments. We found that H₂ emission is often quite strong, correlates with optical low-ionization emission lines and has a surprisingly high excitation temperature. Here, …

Application Of The No-Core Symplectic Shell Model To Beryllium And Carbon Isotopes, Mia Cherise Ferriss

Honors Capstones

No abstract provided.

Testing Galaxy Formation Models With The Ghosts Survey : The Color Profile Of M81'S Stellar Halo., Antonela Monachesi, Eric F. Bell, David J. Radburn-Smith, Marija Vlajic, Roelof S. De Jong, Jeremy Bailin, Julianne J. Dalcanton, Benne W. Holwerda, David Streich

Faculty and Staff Scholarship

We study the properties of the stellar populations in M81’s outermost part, which hereafter we will call the stellar halo, using Hubble Space Telescope (HST) Advanced Camera for Surveys observations of 19 fields from the GHOSTS survey. The observed fields probe the stellar halo out to a projected distance of ∼50 kpc from the galactic center. Each field was observed in both F606W and F814W filters. The 50% completeness levels of the color–magnitude diagrams (CMDs) are typically at 2 mag below the tip of the red giant branch (TRGB). Fields at distances closer than 15 kpc show evidence of disk-dominated …

The Thermodynamics Of Dna Loop Formation, From J To Z, Stephen D. Levene, Stefan M. Giovan, Andreas Hanke, Massa J. Shoura

Physics & Astronomy Faculty Publications

The formation of DNA loops is a ubiquitous theme in biological processes, including DNA replication, recombination and repair, and gene regulation. These loops are mediated by proteins bound at specific sites along the contour of a single DNA molecule, in some cases many thousands of base pairs apart. Loop formation incurs a thermodynamic cost that is a sensitive function of the length of looped DNA as well as the geometry and elastic properties of the DNA-bound protein. The free energy of DNA looping is logarithmically related to a generalization of the Jacobson-Stockmayer factor for DNA cyclization, termed the J factor. …

Stories Of The Stars: The History And Folklore Of Tibetan Ethnoastronomy, Mara Johnson-Groh

Independent Study Project (ISP) Collection

Traditionally, the night sky played an important role in the lives of Tibetans. Stars and constellations were used in navigation and in telling time. Folklore and proverbs surround these constellations and there are myths about the moon and planets as well. However, many of the stories that can be found today either originate in or are influenced by Indian culture. With the introduction of Buddhism to Tibet, came Vedic texts on astrology, which had a profound impact on the culture of ethnoastronomy in the region. Adapted Vedic astrology, merged with practices from China, eventually replaced traditional ethnoastronomy. Because of the …

Rainich-Type Conditions For Null Electrovacuum Spacetimes I, Charles G. Torre

Research Vignettes

In this worksheet I describe local Rainich-type conditions on a spacetime geometry which are necessary and sufficient for the existence of a solution of the Einstein-Maxwell equations with a null electromagnetic field. When it exists, the electromagnetic field is easily constructed.

Determination Of Average Loss Lifetimes For Near‐Earth Electrons In Solar Storms, John Blears

Undergraduate Theses—Unrestricted

The rate of electron wave‐particle scattering in the near‐Earth magnetosphere is investigated using multiple simulations of solar storms from solar cycle 23 (1996‐2005). Simulations are created using the Hot Electron and Ion Drift Integrator (HEIDI) model, which analyzes the drifts of keV‐energy electrons through the inner magnetosphere and identifies the precipitation of these particles into the upper atmosphere. The loss lifetime formulation used by HEIDI, which represents the rate at which the keV‐energy of the electrons is extinguished, predicts unreasonably large loss lifetimes deep in the inner magnetosphere. This discrepancy between the values used by the HEIDI model and those …

Multi-Wavelength Observations Of Supernova 2011ei: Time-Dependent Classification Of Type Iib And Ib Supernovae And Implications For Their Progenitors, Dan Milisavljevic, Raffaella Margutti, Alicia M. Soderberg, Giuliano Pignata, Laura Chomiuk, Robert A. Fesen

Dartmouth Scholarship

We present X-ray, UV/optical, and radio observations of the stripped-envelope, core-collapse supernova (SN) 2011ei, one of the least luminous SNe IIb or Ib observed to date. Our observations begin with a discovery within 1 day of explosion and span several months afterward. Early optical spectra exhibit broad, Type II-like hydrogen Balmer profiles that subside rapidly and are replaced by Type Ib-like He-rich features on the timescale of one week. High-cadence monitoring of this transition suggests that absorption attributable to a high velocity (> 12,000 km/s) H-rich shell is not rare in Type Ib events. Radio observations imply a shock velocity …

Experimental Analysis Of Energy-Based Acoustic Arrays For Measurement Of Rocket Noise Fields, Jarom Henry Giraud

Theses and Dissertations

Microphone arrays are useful for measuring acoustic energy quantities (e.g. acoustic intensity) in the near-field of a full-scale solid rocket motor. Proper characterization of a rocket plume as a noise source will allow for more accurate predictions in engineering models that design for protection of structures, payloads and personnel near the rockets. Acoustic intensity and energy density quantities were measured in three rocket noise fields and have shown that the apparent source region of the rocket becomes smaller and moves upstream as frequency increases. Theoretical results accounting for some scattering and finite-difference errors arising in these types of energy-based measurements …

Brief History Of Curvature, Robert R. Caldwell, Steven S. Gubser

Dartmouth Scholarship

The trace of the stress-energy tensor of the cosmological fluid, proportional to the Ricci scalar curvature in general relativity, is determined on cosmic scales for times ranging from the inflationary epoch to the present day in the expanding Universe. The post-inflationary epoch and the thermal history of the relativistic fluid, in particular the QCD transition from asymptotic freedom to confinement and the electroweak phase transition, leave significant imprints on the scalar curvature. These imprints can be of either sign and are orders of magnitude larger than the values that would be obtained by naively extrapolating the pressureless matter of the …

Superfluidity In Neutron Stars, Samuel J. Witte

Undergraduate Theses—Unrestricted

Nucleon pairing is studied with specific considerations directed toward the possible influence on neutron star cooling. We present an in-depth analysis of BCS theory using realistic nuclear potentials and consider the impact short-range correlations can have on the gap. Gap calculations are incorporated into neutron star cooling simulations and the significance of the 3P2 −3F2 channel in various hadronic cooling models is closely examined. An analysis of the 1S0 gap in neutron matter suggests short-range correlations can drastically alter the magnitude, density range, and temperature dependence of the gap. While the newly constructed 1S0 gap does not significantly alter the …

Impact And Signatures Of Deglaciation On The Cryosphere, Landscape, And Habitability Of Earth And Mars, Nathalie A. Cabrol, Andrew G. Fountain, J. S. Kargel

Geology Faculty Publications and Presentations

Science questions can help bridge Astrobiology and Earth Science disciples around the theme of planetary deglaciation.

An X-Rays Survey Of The Young Stellar Population Of The Lynds 1641 And Iota Orionis Regions, I. Pillitteri, S. J. Wolk, S. T. Megeath, L. Allen, J. Bally, Marc Gagné, R. A. Gutermuth, L. Hartman, G. Micela, P. Myers, J. M. Oliveira, S. Sciortino, F. Walter, L. Rebull, J. Stauffer

Earth & Space Sciences Faculty Publications

We present an XMM-Newton survey of the part of Orion A cloud south of the Orion Nebula. This survey includes the Lynds 1641 (L1641) dark cloud, a region of the Orion A cloud with very few massive stars and hence a relatively low ambient UV flux, and the region around the O9 III star Orionis. In addition to proprietary data, we used archival XMM data of the Orion Nebula Cluster (ONC) to extend our analysis to a major fraction of the Orion A cloud. We have detected 1060 X-ray sources in L1641 and Ori region. About 94% of the sources …

A Biodistribution And Toxicity Study Of Cobalt Dichloride–Nacetyl Cysteine (C4) As An Implantable Mri Marker For Prostate Cancer Treatment, Steven J. Frank, Mary J. Johansen, Karen S. Martirosyan, Mihai Gagea, Carolyn S. Van Pelt

Physics & Astronomy Faculty Publications

Purpose—C4, a cobalt dichloride–N-acetyl cysteine complex, is being developed as a positivesignal magnetic resonance imaging (MRI) marker to localize implanted radioactive seeds in prostate brachytherapy. We evaluated the toxicity and biodistribution of C4 in rats with the goal of simulating systemic effects of potential leakage from C4 MRI markers within the prostate.

Methods—9 μl doses (equivalent to leakage from 120 markers in a human) of control (0.9% sodium chloride), 1% (proposed for clinical use) and 10% C4 solution were injected into the prostates of male Sprague-Dawley rats via laparotomy. Organ toxicity and cobalt disposition in plasma, tissues, feces …

The Spectroscopic Orbits Of Five Solar-Type, Single-Lined Binaries, Francis C. Fekel, Samira Rajabi, Matthew W. Muterspaugh, Michael H. Williamson

Information Systems and Engineering Management Research Publications

We have determined spectroscopic orbits for five single-lined spectroscopic binaries, HD 100167, HD 135991, HD 140667, HD 158222, HD 217924. Their periods range from 60.6 to 2403 days and the eccentricities from 0.20 to 0.84. Our spectral classes for the stars confirm that they are of solar type, F9–G5, and all are dwarfs. Their [Fe/H] abundances, determined spectroscopically, are close to the solar value and on average are 0.12 greater than abundances from a photometric calibration. Four of the five stars are rotating faster than their predicted pseudosynchronous rotational velocities.

Quantum Man, Julian Voss-Andreae

The Transdisciplinary STEAM+ Journal

According to quantum physics, the world is fundamentally quite different than it seems. Drawing inspiration from the underlying nature of reality, former quantum physicist Julian Voss-Andreae created an image of a walking human as a quantum object. Made up of parallel sheets of steel, the sculpture is a metaphor for the counter-intuitive world of quantum physics. Symbolizing the dual nature of matter with the appearance of classical reality on the surface and cloudy quantum behavior underneath, the sculpture seems to consist of solid steel when seen from the front, but dissolves into almost nothing when seen from the side.

Radiative Cooling In Collisionally Ionized And Photoionized Plasmas, Matt Lykins, Gary J. Ferland, Ryan L. Porter, Peter A. M. Van Hoof, R. J. R. Williams, Orly Gnat

Physics and Astronomy Faculty Publications

We discuss recent improvements in the calculation of the radiative cooling in both collisionally ionized and photoionized plasmas. We are extending the spectral simulation code CLOUDY so that as much as possible of the underlying atomic data are taken from external data bases, some created by others and some developed by the CLOUDY team. This paper focuses on recent changes in the treatment of many stages of ionization of iron, and discusses its extensions to other elements. The H- and He-like ions are treated in the isoelectronic approach described previously. Fe II is a special case treated with a large …

Asymmetry Of Magnetosheath Flows And Magnetopause Shape During Low Alfvén Mach Number Solar Wind, B. Lavraud, E. Larroque, E. Budnik, V. Génot, J. E. Borovsky, M. W. Dunlop, K. Nykyri, Et Al.

Publications

Previous works have emphasized the significant influence of the solar wind Alfvén Mach number (MA) on magnetospheric dynamics. Here we report statistical, observational results that pertain to changes in the magnetosheath flow distribution and magnetopause shape as a function of solar wind MA and interplanetary magnetic field (IMF) clock angle orientation. We use all Cluster 1 data in the magnetosheath during the period 2001–2010, using an appropriate spatial superposition procedure, to produce magnetosheath flow distributions as a function of location in themagnetosheath relative to the IMF and other parameters. The results demonstrate that enhanced flows in the magnetosheath are expected …

Quantifying Night Sky Fluctuations: Striving For A Multi-Messenger Astronomy, Rachel K. Nydegger, Shane L. Larson Ph.D.

Browse All Undergraduate research

With LIGO coming back online soon, astronomers are attempting to solve the problems involved with coupling gravitational observations with electromagnetic telescope observations. To do this, my project aims to create all-sky surveys to characterize natural variability to reduce "false-alarm" rates in detections of gravitational emissions.

Effects Of Different Geomagnetic Storm Drivers On The Ring Current: Crcm Results, W D. Cramer, Niescja E. Turner, M C. Fok, N Y. Buzulukova

Physics and Astronomy Faculty Research

The storm-time magnetic disturbance at the Earth's equator, as commonly measured by the Dst index, is induced by currents in the near-Earth magnetosphere. The ring current is generally considered the most important contributor, but other magnetospheric currents have also been found to have significant effects. Of the two main types of solar geomagnetic storm drivers, Coronal Mass Ejections (CMEs) tend to have a much greater impact on Dst than Corotating Interaction Regions (CIRs). Ring current models have been found to underestimate Dst, particularly during storms driven by CIRs. One possible explanation is that the models neglect to handle some aspect …

Andromeda Dwarfs In Light Of Modified Newtonian Dynamics, Stacy S. Mcgaugh

Faculty Scholarship

We compare the recently published velocity dispersions for 17 Andromeda dwarf spheroidals with estimates of the modified Newtonian dynamics predictions, based on the luminosities of these dwarfs, with reasonable stellar mass-to-light values and no dark matter. We find that the two are consistent within the uncertainties. We further predict the velocity dispersions of another 10 dwarfs for which only photometric data are currently available. © 2013. The American Astronomical Society. All rights reserved..

The Spectroscopic Orbit Of The K-Giant Binary Γ Canis Minoris, Francis C. Fekel, Michael H. Williamson, Michael Weber, Klaus G. Strassmeier, Dimitri Pourbaix

Information Systems and Engineering Management Research Publications

We have determined an improved orbit for the bright, evolved, double lined binary γ Canis Minoris. The system has an orbital period of 389.31 days and an eccentricity of 0.2586. We have revised the secondary to primary mass ratio to 0.987. The spectral types of the primary and secondary are K4 III and K1: III, respectively, and the components have a V magnitude difference of 2.2. Orbital fits to the Hipparcos astrometry are not definitive, but they suggest an orbital inclination of ∼ 66°, which produces masses of 1.88 and 1.85 M⊙ for the components. A comparison with evolutionary tracks …

Thin-Shell Mixing In Radiative Wind-Shocks And The L-X Similar To L-Bol Scaling Of O-Star X-Rays, S. P. Owocki, J. O. Sundqvist, David H. Cohen, K. G. Gayley

Physics & Astronomy Faculty Works

X-ray satellites since Einstein have empirically established that the X-ray luminosity from single O-stars scales linearly with bolometric luminosity, L-x similar to 10(-7)L(bol). But straightforward forms of the most favoured model, in which X-rays arise from instability-generated shocks embedded in the stellar wind, predict a steeper scaling, either with mass-loss rate L-x similar to(M)over dot similar to L-bol(1.7) if the shocks are radiative or with L-x similar to (M)over dot(2) similar to L-bol(3.4) if they are adiabatic. This paper presents a generalized formalism that bridges these radiative versus adiabatic limits in terms of the ratio of the shock cooling length …

How To Find Killing Vectors, Charles G. Torre

How to... in 10 minutes or less

We show how to compute the Lie algebra of Killing vector fields of a metric in Maple using the commands KillingVectors and LieAlgebraData. A Maple worksheet and a PDF version can be found below.