Astrophysics and Astronomy Commons^™

Application Of Asymptotic Expansions For Maximum Likelihood Estimators' Errors To Gravitational Waves From Inspiraling Binary Systems: The Network Case, Salvatore Vitale, Michele Zanolin

Publications

This paper describes the most accurate analytical frequentist assessment to date of the uncertainties in the estimation of physical parameters from gravitational waves generated by nonspinning binary systems and Earth-based networks of laser interferometers. The paper quantifies how the accuracy in estimating the intrinsic parameters mostly depends on the network signal to noise ratio (SNR), but the resolution in the direction of arrival also strongly depends on the network geometry. We compare results for 6 different existing and possible global networks and two different choices of the parameter space. We show how the fraction of the sky where the one …

The Polylogarithm And The Lambert W Functions In Thermoelectrics, Muralikrishna Molli, Kamisetty Venkataramaniah, Sree Ram Valluri

Physics and Astronomy Publications

In this work, we determine the conditions for the extremum of the figure of merit, theta², in a degenerate semiconductor for thermoelectric (TE) applications. We study the variation of the function theta² with respect to the reduced chemical potential mu* using relations involving polylogarithms of both integral and nonintegral orders. We present the relevant equations for the thermopower, thermal, and electrical conductivities that result in optimizing theta² and obtaining the extremum equations. We discuss the different cases that arise for various values of r, which depends on the type of carrier scattering mechanism present in the …

Distance Scale Zero Points From Galactic Rr Lyrae Star Parallaxes, G. Fritz Benedict, Barbara E. Mcarthur, Michael W. Feast, Thomas G. Barnes, Thomas E. Harrison, Jacob L. Bean, John W. Menzies, Brian Chaboyer

Dartmouth Scholarship

We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars—five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and κ Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12 ± 0.16 mas; XZ Cyg, 1.67 ± 0.17 mas; SU Dra, 1.42 ± 0.16 mas; RR Lyr, 3.77 ± 0.13 mas; UV Oct, 1.71 ± 0.10 mas; VY Pyx, 6.44 ± 0.23 …

Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol

Faculty Publications

We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting regime, where the on-site repulsion is of the order of or greater than the band width. We compute the equation of state, double occupancy, entropy, uniform susceptibility, and spin correlations for temperatures that are similar to or below the ones achieved in current optical lattice experiments. We provide a quantitative analysis of adiabatic cooling of trapped fermions in two …

Book Review: The Cambridge Atlas Of Herschel Objects, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The Cambridge Atlas of Herschel Objects by James Mullaney and Wil Tirion Cambridge, 2011 183p, 0521138175 $35.00, 9780521138178 $35.00.

Infrared And Upconversion Spectroscopic Studies Of High Er3+Content Transparent Yag Ceramic, M. Pokhrel, G. A. Kumar, P. Samuel, K. I. Ueda, T. Yanagitani, H. Yagi, D. K. Sardar

Physics & Astronomy Faculty Publications

In this article, we report the detailed spectroscopic studies of high Er3+content (50%) transparent YAG ceramic co-doped with nominal Cr3+ content (0.1 mol %). Various radiative and non-radiative spectroscopic properties such as radiative decay time, fluorescence branching ratio, emission/absorption cross sections, internal radiative quantum yields of the infrared and the upconverted emission bands are explored using standard experimental and theoretical methods and compared with YAG single crystal. Results show that although the non-radiative losses are high for 50% Er doped ceramic; several radiative spectral properties are almost in agreement with those for the single crystal YAG. Furthermore, because of the …

Thick Disks Of Edge-On Galaxies Seen Through The Spitzer Survey Of Stellar Structure In Galaxies (S4g) : Lair Of Missing Baryons?, Sebastien Comeron, Bruce G. Elmegreen, Johan H. Knapen, Heikki Salo, Eija Laurikainen, Jarkko Laine, E. Athanassoula, Albert Bosma, Kartik Sheth, Michael W. Regan, Joannah L. Hinz, Armando Gil De Paz, Karin Menendez-Delmestre, Trisha Mizusawa, Juan Carlos Munoz-Mateos, Mark Seibert, Taehyun Kim, Debra M. Elmegreen, Dimitri A. Gadotti, Luis C. Ho, Benne W. Holwerda, Jani Lappalainen, Eva Schinnerer, Ramin Skibba

Faculty and Staff Scholarship

Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T = 3 to T = 8. We fitted one-dimensional luminosity profiles with physically motivated functions—the solutions of two stellar and one gaseous isothermal coupled disks in equilibrium—which are likely to yield more accurate results than other functions used in …

Absolute Properties Of The Eclipsing Binary Star Hy Virginis, Claud H. Sandberg Lacy, Francis C. Fekel

Information Systems and Engineering Management Research Publications

HY Vir is found to be a double-lined F0m+F5 binary star with relatively shallow (0.3 mag) partial eclipses. Previous studies of the system are improved with 7509 differential photometric observations from the URSA WebScope and 8862 from the NFO WebScope, and 68 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope, and the 1 m coudé-feed spectrometer at Kitt Peak National Observatory. Very accurate (better than 0.5%) masses and radii are determined from analysis of the new light curves and radial velocity curves. Theoretical models match the absolute properties of the stars at an age of …

The Properties Of The Stellar Nuclei With The Host Galaxy Morphology In The Acsvcs, Hyun-Chul Lee

Physics & Astronomy Faculty Publications

We have revisited the ACS Virgo Cluster Survey (ACSVCS), a Hubble Space Telescope program to obtain ACS/WFC g and z bands imaging for a sample of 100 early-type galaxies in the Virgo Cluster. In this study, we examine 51 nucleated early-type galaxies in the ACSVCS in order to look into the relationship between the photometric and structural properties of stellar nuclei and their host galaxies. We morphologically dissect galaxies into five classes. We note that (1) the stellar nuclei of dwarf early-type galaxies (dS0, dE, and dE,N) are generally fainter and bluer with g > 18.95 and (g-z) < 1.40 compared to some brighter and redder counterparts of the ellipticals (E) and lenticular galaxies (S0), (2) the g-band half-light radii of stellar nuclei of all dwarf early-type galaxies (dS0, dE, and dE,N) are smaller than 20 pc and their average is about 4 pc, and (3) the colors of red stellar nuclei with (g - z) > 1.40 in bright …

A Study Of The Orbits Of The Logarithmic Potential For Galaxies, Sree Ram Valluri, Paul Wiegert, John Drozd, Matt Dasilva

Physics and Astronomy Publications

The logarithmic potential is of great interest and relevance in the study of the dynamics of galaxies. Some small corrections to the work of Contopoulos & Seimenis (1990) who used the method of Prendergast (1982) to find periodic orbits and bifurca- tions within such a potential are presented. The solution of the orbital radial equation for the purely radial logarithmic potential is then considered using the p-ellipse (pre- cessing ellipse) method pioneered by Struck (2006). This differential orbital equation is a special case of the generalized Burgers equation. The apsidal angle is also deter- mined, both numerically as well as …

Acceleration Of Anomalous Cosmic Rays At The Termination Shock, Udara Senanayake

Von Braun Symposium Student Posters

No abstract provided.

Analysis Of The Hinode Magnetograms, Tae K. Kim, Marina Geneva, Julia Reich, Stefan Wolff

Von Braun Symposium Student Posters

No abstract provided.

High-Resolution Gamma-Ray Spectroscopy With Silicon Photomultipliers, Emily Layden

Von Braun Symposium Student Posters

No abstract provided.

Analysis Of Solar Lyman-Alpha Backscatter Radiation In The Heliosphere, Brian Fayock

Von Braun Symposium Student Posters

No abstract provided.

Lunar Occultation Observer: A Nuclear Astrophysics All-Sky Survey Mission Concept, Riley Freelove

Von Braun Symposium Student Posters

No abstract provided.

The Radioactive Moon, Gaurish Nerurkar

Von Braun Symposium Student Posters

No abstract provided.

Fabrication And Application Of Vertically Aligned Carbon Nanotube Templated Silicon Nanomaterials, Jun Song

Theses and Dissertations

A process, called carbon nanotube templated microfabrication (CNT-M) makes high aspect ratio microstructures out of a wide variety of materials by growing patterned vertically aligned carbon nanotubes (VACNTs) as a framework and then infiltrating various materials into the frameworks by chemical vapor deposition (CVD). By using the CNT-M procedure, a partial Si infiltration of carbon nanotube frameworks results in porous three dimensional microscale shapes consisting of silicon-carbon nanotube composites. The addition of thin silicon shells to the vertically aligned CNTs (VACNTs) enables the fabrication of robust silicon nanostructures with edibility to design a wide range of geometries. Nanoscale dimensions are …

Hubble Space Telescope Imaging Of Post-Starburst Quasars, S. Cales, M. Brotherton, Zhaohui Shang, Vardha Bennert, Gabriela Canalizo, R. Stoll, R. Ganguly, D. Berk, Cassandra Paul, A. Diamond-Stanic

Faculty Publications

We present images of 29 post-starburst quasars (PSQs) from a Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Wide Field Channel Snapshot program. These broadlined active galactic nuclei (AGNs) possess the spectral signatures of massive (Mburst ∼ 1010 M⊙), moderate-aged stellar populations (hundreds of Myr). Thus, their composite nature provides insight into the AGN–starburst connection. We measure quasar-to-host galaxy light contributions via semi-automated two-dimensional light profile fits of point-spread-function-subtracted images. We examine the host morphologies and model the separate bulge and disk components. The HST/ACS-F606W images reveal an equal number of spiral (13/29) and early-type (13/29) hosts, with the …

From The Big Bang To The Swaner Ecocenter: The Cosmic Biography Of Atoms, Shane L. Larson

Public Talks

No abstract provided.

Tidal Perturbations To The Gravitational Inspiral Of J0651+2844, Matthew J. Benacquista, Kelly Holley-Bockelmann

Physics & Astronomy Faculty Publications

The recently discovered J0651+2844 is a detached, eclipsing white dwarf binary with an orbital period of 765 s. We investigate the prospects for the detection of gravitational radiation from this system and estimate the effect of the tidal deformation of the low-mass component on the period evolution of the system. Because of the high inclination of the system, the amplitude of the gravitational waves at Earth will be as much as a factor of two lower than that from an optimally oriented system. The dominant contribution of tidal corrections to the period evolution comes from the increase in rotational energy …

Acurate Low-Mass Stellar Models Of Koi-126, Gregory A. Feiden, Brian Chaboyer, Aaron Dotter

Dartmouth Scholarship

The recent discovery of an eclipsing hierarchical triple system with two low-mass stars in a close orbit (KOI-126) by Carter et al. (2011) appeared to reinforce the evidence that theoretical stellar evolution models are not able to reproduce the observational mass-radius relation for low-mass stars. We present a set of stellar models for the three stars in the KOI-126 system that show excellent agreement with the observed radii. This agreement appears to be due to the equation of state implemented by our code. A significant dispersion in the observed mass-radius relation for fully convective stars is demonstrated; indicative of the …

Surprising Variations In The Rotation Of The Chemically Peculiar Stars Cu Virginis And V901 Orionis, Zdeněk Mikulášek, Jiří Krtička, Gregory W. Henry, Jan Janík, Juraj Zverko, Jozef Žižňovský, Miloslav Zejda, Jiri Liška, Pavel Zvěřina, D. O. Kudrjavtsev, Iosif I. Romanyuk, N. A. Sokolov, Theresa Lüftinger, Corrado Trigilio, Coralie Neiner, S. N. De Villiers

Information Systems and Engineering Management Research Publications

Context. The majority of magnetic chemically peculiar (mCP) stars exhibit periodic light, radio, spectroscopic and spectropolarimetric variations that can be adequately explained by the model of a rigidly rotating main-sequence star with persistent surface structures. CU Vir and V901 Ori belong among these few mCP stars whose rotation periods vary on timescales of decades.

Aims. We aim to study the stability of the periods in CU Vir and V901 Ori using all accessible observational data containing phase information.

Methods. We collected all available relevant archived observations supplemented with our new measurements of these stars and analysed the period variations of …

Critical Differences And Clues In Eta Car's 2009 Event, Andrea Mehner, Kris Davidson, John C. Martin, Roberta M. Humphreys, Kazunori Ishibashi, Gary J. Ferland

Physics and Astronomy Faculty Publications

We monitored Eta Carinae with the Hubble Space Telescope WFPC2 and Gemini GMOS throughout the 2009 spectroscopic event, which was expected to differ from its predecessor in 2003. Here we report major observed differences between events and their implications. Some of these results were quite unexpected. (1) The UV brightness minimum was much deeper in 2009. This suggests that physical conditions in the early stages of an event depend on different parameters than the "normal" inter-event wind. Extra mass ejection from the primary star is one possible cause. (2) The expected He II λ4687 brightness maximum was followed several weeks …

The Real Orbital Period Of The Double-Lined Spectroscopic Binary Hd 31738, Francis C. Fekel, Roger F. Griffin

Information Systems and Engineering Management Research Publications

No abstract provided.

Initial Calibration Of Ccd Images For The Dark Energy Survey, Deokgeun Park '12, H. Thomas Diehl, Douglas Tucker

Student Publications & Research

Astronomical images taken from a telescope must go through “astronomical image processing” to remove instrumental signatures. The Dark Energy Survey (DES), which will start operations in 2012, will use a 570 megapixel Dark Energy Camera (DECam) to study the mystery of the acceleration of the expanding universe. The DECam will use DES filters and 74 of a new type of astronomical Charge Coupled Device (CCD) that is particularly efficient in detecting near-infrared light. Together, the DES filters and DECam CCDs are optimized for the measurement of redshifts of distant galaxies. In preparation for the DES, data were collected from the …

Quantified H I Morphology – Ii. Lopsidedness And Interaction In Whisp Column Density Maps., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden, E. C. Elson

Faculty and Staff Scholarship

Lopsidedness of the gaseous disc of spiral galaxies is a common phenomenon in disc morphology, profile and kinematics. Simultaneously, the asymmetry of a galaxy’s stellar disc, in combination with other morphological parameters, has seen extensive use as an indication of recent merger or interaction in galaxy samples. Quantified morphology of stellar spiral discs is one avenue to determine the merger rate over much of the age of the Universe. In this paper, we measure the quantitative morphology parameters for the H I column density maps from the Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies (WHISP). These are …

Quantified H I Morphology – Iv. The Merger Fraction And Rate In Whisp., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden

Faculty and Staff Scholarship

The morphology of the atomic hydrogen (H I) disc of a spiral galaxy is the first component to be disturbed by a gravitational interaction such as a merger between two galaxies. We use a simple parametrization of the morphology of H I column density maps of the Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies (WHISP) project to select those galaxies that are likely undergoing a significant interaction. Merging galaxies occupy a particular part of parameter space defined by Asymmetry (A), the relative contribution of the 20 per cent brightest pixels to the second-order moment of the column …

Astr 403: Galactic And Extragalactic Astronomy, Edward Schmidt

Department of Physics and Astronomy: Syllabi

Syllabus for ASTR 403 Galactic and Extragalactic Astronomy for Fall 2011 semester.

Quantified H I Morphology – V. H I Discs In The Virgo Cluster., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, W. Van Driel

Faculty and Staff Scholarship

We explore the quantified morphology of atomic hydrogen (H i) discs in the Virgo cluster. These galaxies display a wealth of phenomena in their H i morphology, e.g., tails, truncation and warps. These morphological disturbances are related to the ram pressure stripping and tidal interaction that galaxies undergo in this dense cluster environment. To quantify the morphological transformation of the H i discs, we compute the morphological parameters of Concentration, Asymmetry, Smoothness, Gini and M20 and our own GM for 51 galaxies in 48 H i column density maps from the VLA Imaging of Virgo spirals in Atomic gas (VIVA) …

Quantified H I Morphology – I. Multi-Wavelength Analysis Of The Things Galaxies., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden, E. C. Elson

Faculty and Staff Scholarship

Galaxy evolution is driven to a large extent by interactions and mergers with other galaxies and the gas in galaxies is extremely sensitive to the interactions. One method to measure such interactions uses the quantified morphology of galaxy images. Well-established parameters are Concentration, Asymmetry, Smoothness, Gini and M20 of a galaxy image. Thus far, the application of this technique has mostly been restricted to rest-frame ultraviolet and optical images. However, with the new radio observatories being commissioned [South African Karoo Array Telescope (MeerKAT), Australian SKA Pathfinder (ASKAP), Extended Very Large Array (EVLA), Westerbork Synthesis Radio Telescope/APERture Tile In Focus instrument …