Astrophysics and Astronomy Commons^™

Book Review: Spectral Atlas For Amateur Astronomers: A Guide To The Spectra Of Astronomical Objects And Terrestrial Light Sources, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Spectral Atlas for Amateur Astronomers: A Guide to the Spectra of Astronomical Objects and Terrestrial Light Sources by Richard Walker. Cambridge 2017, 277 p bibl index, 9781107165908 $89.99, 9781316731048 $72.00

Cataclysmic Variable Stars In The Sloan Digital Sky Survey, Sinead Humphrey, Samantha Smiley, Andres Munoz, Brian Saboriendo

DePaul Discoveries

The purpose of this study is to identify Cataclysmic Variables (CVs) using spectroscopic and photometric data. CVs are useful for studying plasma physics in extreme conditions such as the high temperature and strong magnetic fields seen in CV accretion disks. They are also critical for understanding the evolution of binary stars, both in the field and in globular clusters. This project used photometric and spectroscopic data from the Sloan Digital Sky Survey (SDSS) to identify and classify CVs. 6,000 objects were selected based on multi-color criteria and analyzed using spectral data. Approximately 1% of these objects in the sample were …

Planet-Driven Spiral Arms In Protoplanetary Disks. I. Formation Mechanism, Jaehan Bae, Zhaohuan Zhu

Physics & Astronomy Faculty Research

Protoplanetary disk simulations show that a single planet can excite more than one spiral arm, possibly explaining the recent observations of multiple spiral arms in some systems. In this paper, we explain the mechanism by which a planet excites multiple spiral arms in a protoplanetary disk. Contrary to previous speculations, the formation of both primary and additional arms can be understood as a linear process when the planet mass is sufficiently small. A planet resonantly interacts with epicyclic oscillations in the disk, launching spiral wave modes around the Lindblad resonances. When a set of wave modes is in phase, they …

Planet-Driven Spiral Arms In Protoplanetary Disks. Ii. Implications, Jaehan Bae, Zhaohuan Zhu

Physics & Astronomy Faculty Research

We examine whether various characteristics of planet-driven spiral arms can be used to constrain the masses of unseen planets and their positions within their disks. By carrying out two-dimensional hydrodynamic simulations varying planet mass and disk gas temperature, we find that a larger number of spiral arms form with a smaller planet mass and a lower disk temperature. A planet excites two or more spiral arms interior to its orbit for a range of disk temperatures characterized by the disk aspect ratio $0.04\leqslant {(h/r)}_{p}\leqslant 0.15$, whereas exterior to a planet's orbit multiple spiral arms can form only in cold disks …

A Spatially-Resolved X-Ray Spectroscopic Analysis Of The Luminous Northeastern Rim Of The Galactic Supernova Remnant W28 (G6.4-0.1), Sarah Norris, Thomas Pannuti

Celebration of Student Scholarship Poster Sessions Archive

No abstract provided.

The Nanograv 11 Year Data Set: Pulsar-Timing Constraints On The Stochastic Gravitational-Wave Background, Zaven Arzoumanian, P. T. Baker, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, S. Chatterjee, B. Christy, ‪Jeffrey S. Hazboun, Jing Luo

Physics & Astronomy Faculty Publications

We search for an isotropic stochastic gravitational-wave background (GWB) in the newly released 11 year data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). While we find no evidence for a GWB, we place constraints on a population of inspiraling supermassive black hole (SMBH) binaries, a network of decaying cosmic strings, and a primordial GWB. For the first time, we find that the GWB constraints are sensitive to the solar system ephemeris (SSE) model used and that SSE errors can mimic a GWB signal. We developed an approach that bridges systematic SSE differences, producing the first pulsar-timing …

Low Metallicities And Old Ages For Three Ultra-Diffuse Galaxies In The Coma Cluster, Meng Gu, Charlie Conroy, David Law, Pieter Van Dokkum, Renbin Yan, David Wake, Kevin Bundy, Allison Merritt, Roberto Abraham, Jielai Zhang, Matthew Bershady, Dmitry Bizyaev, Jonathan Brinkmann, Niv Drory, Kathleen Grabowski, Karen Masters, Kaike Pan, John Parejko, Anne-Marie Weijmans, Kai Zhang

Physics and Astronomy Faculty Publications

A large population of ultra-diffuse galaxies (UDGs) was recently discovered in the Coma cluster. Here we present optical spectra of three such UDGs, DF 7, DF 44, and DF 17, which have central surface brightnesses of μ_g ≈ 24.4–25.1 mag arcsec⁻². The spectra were acquired as part of an ancillary program within the SDSS-IV MaNGA Survey. We stacked 19 fibers in the central regions from larger integral field units (IFUs) per source. With over 13.5 hr of on-source integration, we achieved a mean signal-to-noise ratio in the optical of 9.5 Å⁻¹, 7.9 Å⁻¹, …

An Analysis Of Frenkel Defects And Backgrounds Modeling For Supercdms Dark Matter Searches, Matthew Stein

Physics Theses and Dissertations

Years of astrophysical observations suggest that dark matter comprises more than ~80 % of all matter in the universe. Particle physics theories favor a weakly-interacting particle that could be directly detected in terrestrial experiments. The Super Cryogenic Dark Matter Search (SuperCDMS) Collaboration operates world-leading experiments to directly detect dark matter interacting with ordinary matter. The SuperCDMS Soudan experiment searched for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei in low-temperature germanium detectors.

During the operation of the SuperCDMS Soudan experiment, ²¹⁰Pb sources were installed to study background rejection of the Ge detectors. Data from these sources …

The Dark Energy Survey Image Processing Pipeline, E. Morganson, R. A. Gruendl, F. Menanteau, M. Carrasco Kind, Y.-C. Chen, G. Daues, A. Drlica-Wagner, D. N. Friedel, M. Gower, M. W. G. Johnson, M. D. Johnson, R. Kessler, F. Paz-Chinchón, D. Petravick, C. Pond, B. Yanny, S. Allam, R. Armstrong, Wayne A. Barkhouse, K. Bechtol, A. Benoit-Lévy, G. M. Bernstein, E. Bertin, E. Buckley-Geer, R. Covarrubias, S. Desai, H. T. Diehl, D. A. Goldstein, D. Gruen, T. S. Li, H. Lin, J. Marriner, J. J. Mohr, E. Neilsen, C.-C. Ngeow, K. Paech, E. S. Rykoff, M. Sako, I. Sevilla-Noarbe, E. Sheldon, F. Sobreira, D. L. Tucker, W. Wester

Physics Faculty Publications

The Dark Energy Survey (DES) is a five-year optical imaging campaign with the goal of understanding the origin of cosmic acceleration. DES performs a ~5000 deg2 survey of the southern sky in five optical bands (g, r, i, z, Y) to a depth of ~24th magnitude. Contemporaneously, DES performs a deep, time-domain survey in four optical bands (g, r, i, z) over ~27 deg2. DES exposures are processed nightly with an evolving data reduction pipeline and evaluated for image quality to determine if they need to be retaken. Difference imaging and transient source detection are also …

Search For Tensor Vector And Scalar Polarizations In The Stochastic Gravitational-Wave Background, B. P. Abbott, R. Abbott, T. D. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano, Robert Stone, Wenhui Wang

Physics & Astronomy Faculty Publications

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find …

Constraints On Cosmic Strings Using Data From The First Advanced Ligo Observing Run, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Marc E. Normandin, Volker Quetschke, Malik Rakhmanov, Joseph D. Romano, Robert Stone

Physics & Astronomy Faculty Publications

Cosmic strings are topological defects which can be formed in grand unified theory scale phase transitions in the early universe. They are also predicted to form in the context of string theory. The main mechanism for a network of Nambu-Goto cosmic strings to lose energy is through the production of loops and the subsequent emission of gravitational waves, thus offering an experimental signature for the existence of cosmic strings. Here we report on the analysis conducted to specifically search for gravitational-wave bursts from cosmic string loops in the data of Advanced LIGO 2015-2016 observing run (O1). No evidence of such …

Full Band All-Sky Search For Periodic Gravitational Waves In The O1 Ligo Data, B. P. Abbott, Teviet Creighton, Mario C. Diaz, S. R. Morriss, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, Robert Stone, Darkhan Tuyenbayev, Wenhui Wang

Physics & Astronomy Faculty Publications

We report on a new all-sky search for periodic gravitational waves in the frequency band 475-2000 Hz and with a frequency time derivative in the range of [-1.0,+0.1]×10-8 Hz/s. Potential signals could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our Galaxy. This search uses the data from Advanced LIGO's first observational run O1. No gravitational-wave signals were observed, and upper limits were placed on their strengths. For completeness, results from the separately published low-frequency search 20-475 Hz are included as well. Our lowest upper limit on worst-case (linearly polarized) strain amplitude h0 is ∼4×10-25 …

Primordial Black Holes In The Cosmological Context And Transient Electromagnetic Signatures From Merging Black Hole Binaries, Jared Robert Rice

UNLV Theses, Dissertations, Professional Papers, and Capstones

The cosmological evolution of primordial black holes (PBHs) is presented via analysis of the accretion and evaporation histories of the holes. The ultimate end of any BH is evaporation — a spectacular seconds-long burst of high-energy radiation and particles. The critical initial mass of a PBH undergoing current era evaporation is ∼ 510 trillion grams. A near- critical mass PBH will not accrete radiation or matter in sufficient quantity to retard its inevitable evaporation, if the hole remains within an average volume of the universe. The gravitational waves (GWs) from five BH binary merger events discovered by the LIGO/Virgo collaborations …

Recovering Stellar Population Parameters Via Two Full-Spectrum Fitting Algorithms In The Absence Of Model Uncertainties, Junqiang Ge, Renbin Yan, Michele Cappellari, Shude Mao, Hongyu Li, Youjun Lu

Physics and Astronomy Faculty Publications

Using mock spectra based on Vazdekis/MILES library fitted within the wavelength region 3600–7350 Å, we analyse the bias and scatter on the resulting physical parameters induced by the choice of fitting algorithms and observational uncertainties, but avoid effects of those model uncertainties. We consider two full-spectrum fitting codes: PPXF and STARLIGHT, in fitting for stellar population age, metallicity, mass-to-light ratio, and dust extinction. With PPXF, we find that both the bias μ in the population parameters and the scatter σ in the recovered logarithmic values follows the expected trend μ ∝ σ ∝ 1/(S/N)⁠. The bias increases for younger ages …

High-Throughput Automated Multi-Target Super-Resolution Imaging, Farzin Farzam

Physics & Astronomy ETDs

Super-resolution microscopy techniques developed through the past few decades enable us to surpass the classical diffraction limit of light, and thus open new doors to investigate the formerly inaccessible world of nanometer-sized objects. Most importantly, by using super-resolution microscopy, one can visualize sub-cellular structures in the range of 10 to 200 nm. At this range, we can investigate exciting problems in biology and medicine by visualizing protein-protein interactions and spatiotemporal analysis of structures of interest on the surface or inside cells. These techniques (collectively known as nanoscopy) have a high impact on understanding and solving biological questions. This dissertation starts …

Dispersive Quantum Interface With Atoms And Nanophotonic Waveguides, Xiaodong Qi

Physics & Astronomy ETDs

Strong coupling between atoms and light is critical for quantum information processing and precise sensing. A nanophotonic waveguide is a promising platform for realizing an atom-light interface that reaches the strong coupling regime. In this dissertation, we study the dispersive response theory of the nanowaveguide system as the means to create an entangling atom-light interface, with applications to quantum non-demolition (QND) measurement and spin squeezing.

We calculate the dyadic Green's function, which determines the scattering of light by atoms in the presence of a nanowaveguide, and thus the phase shift and polarization rotation induced on the guided light. The Green's …

The Nature Of Deeply Buried Ultraluminous Infrared Galaxies: A Unified Model For Highly Obscured Dusty Galaxy Emission, J. A. Marshall, Moshe Elitzur, L. Armus, T. Diaz-Santos, V. Charmandaris

Physics and Astronomy Faculty Publications

We present models of deeply buried ultraluminous infrared galaxy (ULIRG) spectral energy distributions (SEDs) and use them to construct a three-dimensional diagram for diagnosing the nature of observed ULIRGs. Our goal is to construct a suite of SEDs for a very simple model ULIRG structure, and to explore how well this simple model can (by itself) explain the full range of observed ULIRG properties. We use our diagnostic to analyze archival Spitzer Space Telescope Infrared Spectrograph data of ULIRGs and find that: (1) in general, our model does provide a comprehensive explanation of the distribution of mid-IR ULIRG properties; (2) …

Helium In The Eroding Atmosphere Of An Exoplanet, Jess J. Spake, David K. Sing, Tom M. Evans, Antonija Oklopčić, Vincent Bourrier, Laura Kreidberg, Benjamin V. Rackham, Jonathan Irwin, David Ehrenreich, Aurélien Wyttenbach, Hannah R. Wakeford, Yifan Zhou, Katy L. Chubb, Nikolay Nikolov, Jayesh M. Goyal, Gregory W. Henry, Michael H. Williamson, Sarah Blumenthal, David R. Anderson, Coel Hellier, David Charbonneau, Stephane Udry, Nikku Madhusudhan

Information Systems and Engineering Management Research Publications

Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres1. Searches for helium, however, have hitherto been unsuccessful2. Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near-infrared transmission spectrum of the warm gas giant3 WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The …

Against Common Sense, Channon Visscher

Faculty Work Comprehensive List

"Scientific inquiry... allows for the exploration of phenomena that would otherwise remain beyond human intuition."

Posting about ­­­­­­­­beauty and truth in creation from In All Things - an online journal for critical reflection on faith, culture, art, and every ordinary-yet-graced square inch of God’s creation.

https://inallthings.org/against-common-sense/

Cosmological Distance Measurements With Rotse Supernovae Iip And Observational Systematics On Desi Emission Line Galaxy Clustering, Govinda Dhungana

Physics Theses and Dissertations

Both Supernovae (SNe) and Baryon Acoustic Oscillations (BAO) surveys emerged as complementary probes of the expansion history of the universe in the last few decades. SNe Ia cosmology has reached the systematic limits in the optical surveys. The most frequently occuring SNe Type IIP are emerging as equally rich distance probes for the next generation larger surveys. In this thesis, I highlight the astrophysical observables of these events in the context of ROTSE III SN survey and using the ROTSE SNe IIP sample, I present calibration in the framework of expanding photosphere method (EPM) to use them as cosmological distance …