Astrophysics and Astronomy Commons^™

The Implementation Of The Shear Correlation Function And The Matter Power Spectrum In R, Allison A. Scheppelmann, Deborah J. Bard

STAR Program Research Presentations

Weak gravitational lensing is an important tool in understanding the large-scale structure of the universe. One component in understanding the effect of weak gravitational lensing is the shear correlation function and matter power spectrum. The calculation of these values is often complicated and time consuming. In order to decrease the cost of these calculations they were implemented in R using parallelization. This resulted in the calculations completing faster and the process to be easily changed in order to fit the need of each researcher using the algorithms created in R.

Electric Currents Due To Stress-Activated Positive Hole Charge Carriers In Ice, Cary T. Keller P.E., Friedemann T. Freund, Dale P. Cruikshank

STAR Program Research Presentations

Jupiter’s satellite Europa, whose surface is composed of ice with a possible water ocean beneath, could conceivably serve as an abode for extraterrestrial life. This and other icy celestial bodies may contain organic macromolecular solid material that is produced when surface ices are exposed to ultraviolet radiation and/or electrical energy. Tidal and tectonic stresses or meteorite impacts in icy crusts may produce electrical discharges, which would provide the energy for in-situ synthesis of the organic solids. This electrical energy can be provided by positive hole charge carrier activation. Positive holes exhibit properties such as the ability to flow out of …

Telescope Assembly Alignment Simulator Performance Optimization, Joshua G. Thompson, Brian Eney, Zaheer Ali, Bob Thompson

STAR Program Research Presentations

The Telescope Assembly Alignment Simulator (TAAS) calibrates scientific instruments (SI’s) that are installed on the Stratospheric Observatory For Infrared Astronomy (SOFIA). An SI’s accuracy is directly dependent on the consistent performance of the TAAS, which has never been fully characterized. After designing various thermal and optical experiments to identify the current unknowns of TAAS, we now have a far better grasp on how the equipment behaves.

A Comparison Of Broad Iron Emission Lines In Archival Data Of Neutron Star Low-Mass X-Ray Binaries, Edward M. Cackett, Jon M. Miller, Rubens C. Reis, Andrew C. Fabian, Didier Barret

Physics and Astronomy Faculty Research Publications

Relativistic X-ray disklines have been found in multiple neutron star low-mass X-ray binaries, in close analogy with black holes across the mass scale. These lines have tremendous diagnostic power and have been used to constrain stellar radii and magnetic fields, often finding values that are consistent with independent timing techniques. Here, we compare CCD-based data from Suzaku with Fe K line profiles from archival data taken with gas-based spectrometers. In general, we find good consistency between the gas-based line profiles from EXOSAT, BeppoSAX, and RXTE and the CCD data from Suzaku, demonstrating that the broad profiles seen are intrinsic to …

Nasa Flight Opportunities Program (Fop) Platform Tradeoffs Analysis, Stephanie Kugler, Dougal Maclise

STAR Program Research Presentations

The Flight Opportunities Program (FOP) exemplifies NASA’s shift in policy from a public driven space industry towards an emphasis on public-private partnerships. The Payloads team, as part of FOP, is responsible for soliciting, selecting and shepherding payloads that require flight testing in order to mature technologies, not only to reduce risk in a deep space or manned space missions, but also to develop critical technologies with multiple applications in space. Several companies have been awarded contracts to provide these flight opportunities and each have unique capabilities to fly payloads in environments that closely imitate the environment of space missions. As …

Leds And Astronomy, Britny N. Delp, Stephen M. Pompea

STAR Program Research Presentations

Using a Czerny-Turner spectrometer, 45 different types of outdoor lights were categorized. These spectra were used to determine how useful the light is to human eyes and how dark skies friendly these lights are. Dark skies friendly lighting means that little to no light shines above a right angle to the light, and should emit as little as possible below 500nm (green) wavelengths. The short wavelengths present a problem to astronomers in the form of Rayleigh scattering. The following criterion were used in selecting the best source for urban and rural lighting: color rendition measured by color rendering index (CRI), …

Effect Of Particle Statistics In Strongly Correlated Two-Dimensional Hubbard Models, Ehsan Khatami, Marcos Rigol

Faculty Publications

We study the onset of particle statistics effects as the temperature is lowered in strongly correlated two-dimensional Hubbard models. We utilize numerical linked-cluster expansions and focus on the properties of interacting lattice fermions and two-component hard-core bosons. In the weak-coupling regime, where the ground state of the bosonic system is a superfluid, the thermodynamic properties of the two systems at half filling exhibit very large differences even at high temperatures. In the strong-coupling regime, where the low-temperature behavior is governed by a Mott insulator for either particle statistics, the agreement between the thermodynamic properties of both systems extends to regions …

Student-Teacher Interactions For Bringing Out Student Ideas About Energy, Benedikt W. Harrer, Michael Wittmann, Rachel Scherr

Faculty Publications

Modern middle school science curricula use group activities to help students express their thinking and enable them to work together like scientists. We are studying rural 8th grade science classrooms using materials on energy. Even after spending several months with the same curriculum on other physics topics, students' engagement in group activities seems to be restricted to creating lists of words that are associated with energy. Though research suggests that children have rich and potentially valuable ideas about energy, our students don't seem to spontaneously use and express their ideas in the classroom. Only within or after certain interactions with …

Residual Cooling And Persistent Star Formation Amid Active Galactic Nucleus Feedback In Abell 2597, G. R. Tremblay, C. P. O'Dea, S. A. Baum, T. E. Clarke, C. L. Sarazin, J. N. Bregman, F. Combes, M. Donahue, A. C. Edge, A. C. Fabian, Gary J. Ferland, B. R. Mcnamara, R. Mittal, J. B. R. Oonk, A. C. Quillen, H. R. Russell, J. S. Sanders, P. Salomé, G. M. Voit, R. J. Wilman, M. W. Wise

Physics and Astronomy Faculty Publications

New Chandra X-ray and Herschel Far-Infrared (FIR) observations enable a multiwavelength study of active galactic nucleus (AGN) heating and intracluster medium (ICM) cooling in the brightest cluster galaxy (BCG) of Abell 2597 (z= 0.0821). The new Chandra observations reveal the central ≲30 kpc X-ray cavity network to be more extensive than previously thought, and associated with enough enthalpy to theoretically inhibit the inferred classical cooling flow. Nevertheless, we present new evidence, consistent with previous results, that a moderately strong residual cooling flow is persisting at 4–8 per cent of the classically predicted rates in a spatially structured manner …

Information Content Of Spontaneous Symmetry Breaking, Marcelo Gleiser, Nikitas Stamatopoulos

Dartmouth Scholarship

We propose a measure of order in the context of nonequilibrium field theory and argue that this measure, which we call relative configurational entropy (RCE), may be used to quantify the emergence of coherent low-entropy configurations, such as time-dependent or time-independent topological and nontopological spatially extended structures. As an illustration, we investigate the nonequilibrium dynamics of spontaneous symmetry breaking in three spatial dimensions. In particular, we focus on a model where a real scalar field, prepared initially in a symmetric thermal state, is quenched to a broken-symmetric state. For a certain range of initial temperatures, spatially localized, long-lived structures known …

Variability Studies Of Multi-Wavelength Data From Gamma-Ray Blazars Mrk 421 And Mrk 501, Brandon Becker

Physics

In this thesis we take astronomical multi-wavelength data from nearby blazars Markarian 421 and Markarian 501 and perform computational analysis and correlative studies to determine any possible time lag across different bands of our targets as well as to measure the statistical significance of this calculated result. The data was taken over the interval of December 2010 to May 2012 from multiple instruments spanning a broad range of wavelengths. We used the Discrete Correlation Function (DCF) to determine the time lag factor across data set pairs, focusing on X-ray and Very-High-Energy (VHE; >100 GeV) data. To establish the significance of …

Star-Disk Interaction In Herbig Ae/Be Stars, Christa Speights

All Theses

The question of the mechanism of certain types of stars is important. Classical T Tauri (CTTS) stars accrete magnetospherically, and Herbig Ae/Be stars (higher-mass analogs to CTTS) are thought to also accrete magnetospherically, but the source of a kG magnetic field is unknown, since these stars have radiative interiors. For magnetospheric accretion, an equation has been derived (Hartmann, 2001) which relates the truncation radius, stellar radius, stellar mass, mass accretion rate and magnetic field strength.
Currently the magnetic field of Herbig stars is known to be somewhere between 0.1 kG and 10 kG. One goal of this research is to …

Stability Of Phyllosilicates On Mars, Patricia Gavin

Graduate Theses and Dissertations

This study investigates the stability of phyllosilicates on the surface of Mars through laboratory experiments and analysis of terrestrial analogs. Phyllosilicates are mostly found in the oldest Noachian terrains on Mars and hence hold clues to the planet's earliest aqueous and geologic history. Phyllosilicates relevant to Mars were heated up to ~1100°C for up to 24 hours and impacted with projectile velocities up to ~4.5 km/s. Heated samples were analyzed using x-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy in the near- (NIR, 1.0-2.5 µm) and mid-infrared (MIR, 5.0-15.0 µm) ranges. Impacted samples were also analyzed using Raman spectroscopy …

The Power Of Thermonuclear Supernovae After One Year, Ginger Bryngelson

All Dissertations

Type Ia supernovae (SNe Ia), the thermonuclear explosion of a white dwarf, shape our understanding of the expansion of the universe with the use of their uniformity in distance determinations. Powered by radioactivity synthesized in the explosion, they fade slowly over hundreds of days. Sometime after 200 days, the continually expanding ejecta allows γ-rays from 56 Ni and 56 Co decays to escape, and soon any radioactive power contributing to lighting up the SN comes from positrons formed in 19% of 56 Co
decays.
While at first it seemed that positrons escaped through the thinning ejecta, it has become apparent …

Subsurface Planetary Investigation Techniques And Their Role For Assessing Subsurface Planetary Composition, Ahmed Elshafie

Graduate Theses and Dissertations

Subsurface planetary investigation techniques are of high interest and importance for the scientific community. Not only they can enhance our knowledge of the history of planetary formation but also can lead to information about its future. Whether the investigation is being conducted remotely using imagers, radars or physically using penetrometers or drills, a pre-existed knowledge of the mechanical and electrical properties of the subsurface regolith should be acquired for better data interpretation and analysis. Therefore, the main objective of this work is to investigate the mechanical and electrical properties of planetary analogs, understand their role for assessing the subsurface structure …

Orbital Periodicities Reflected In Ancient Surfaces Of Our Solar System And The Implications For A Record Of Early Life, Dixie Lee Androes

Graduate Theses and Dissertations

Uniformitarian processes, governed by invariant physical laws, remain the most reliable source for reconstructing the past. Driving many of the repetitive, predictable processes are the orbital dynamics of the Sun-Planet-Moon systems. Astronomical periodicities range from a few hours (tides) to thousands of years (Milankovitch). These periodicities, combined with geomorphic observations of planetary surfaces, constrain the time-dependent processes and allow for reconstruction of events and conditions favorable for sedimentary accumulations. This research suggests that seasonal sedimentary processes are dominant on Titan and Mars, and have played a significant role in the formation of ancient banded-iron formations (BIF's) on Earth.

Earth, Mars, …

New Approach To Time Domain Classification Of Broadband Noise In Gravitational Wave Data, Soma Mukherjee, P. Rizwan, R. Biswas

Physics & Astronomy Faculty Publications

Transient broadband noise in gravitational wave (GW) detectors-also known as noise triggers (referred to as triggers for brevity)-can often be a deterrant to the efficiency with which astrophysical search pipelines detect sources. It is important to understand their instrumental or environmental origin so that they could be eliminated or accounted for in the data. Since the number of triggers is large, data mining approaches such as clustering and classification are useful tools for this task. Classification of triggers based on a handful of discrete properties has been done in the past. A rich information content is available in the waveform …

The Gas/Dust Ratio Of Circumstellar Disks: Testing Models Of Planetesimal Formation, David Horne, Erika Gibb, Terrence W. Rettig, Sean D. Brittain, David Tilley, Dinshaw Balsara

Publications

We present high-resolution, near-infrared NIRSPEC observations of CO absorption toward six class II T Tauri stars: AA Tau, DG Tau, IQ Tau, RY Tau, CW Tau, and Haro 6–5b. 12CO overtone absorption lines originating from the circumstellar disk of each object were used to calculate line-of-sight gas column densities toward each source. We measured the gas/dust ratio as a function of disk inclination, utilizing measured visual extinctions and inclinations for each star. The majority of our sources show further evidence for a correlation between the gas/dust columndensity ratio and disk inclination similar to that found by Rettig et al.

The Hd 192263 System: Planetary Orbital Period And Stellar Variability Disentangled, D. Dragomir, S. R. Kane, G. W. Henry, D. R. Ciardi, D. A. Fischer, A. W. Howard, Eric L.N. Jensen, G. Laughlin, S. Mahadevan, J. M. Matthews, G. Pilyavsky, K. Von Braun, S. X. Wang, J. T. Wright

Physics & Astronomy Faculty Works

As part of the Transit Ephemeris Refinement and Monitoring Survey, we present new radial velocities and photometry of the HD 192263 system. Our analysis of the already available Keck-HIRES and CORALIE radial velocity measurements together with the five new Keck measurements we report in this paper results in improved orbital parameters for the system. We derive constraints on the size and phase location of the transit window for HD 192263b, a Jupiter-mass planet with a period of 24.3587 +/- 0.0022 days. We use 10 years of Automated Photoelectric Telescope photometry to analyze the stellar variability and search for planetary transits. …

Veritas Observations Of The Nova In V407 Cygni, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 × 10–12 erg cm–2 …