Other Astrophysics and Astronomy Commons^™

Pathfinding Fast Radio Bursts Localizations Using Very Long Baseline Interferometry, Pranav Rohit Sanghavi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Fast radio bursts (FRBs) are millisecond-duration, bright radio transients of extragalactic origin. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope’s CHIME/FRB instrument and other radio telescopes across the globe have detected hundreds of FRBs. Their origins are a mystery. Precise localization within the host is critical to distinguish between progenitor models. This can be achieved through Very Long Baseline Interferometry (VLBI). Until now, VLBI localizations have only been carried out in targeted follow-up observations of some repeating sources which comprise a small fraction of the FRBs.

For this work, an interferometric array of 6m dishes was constructed at the Green …

Impact Of Radio Frequency Interference And Real-Time Spectral Kurtosis Mitigation, Evan T. Smith

Graduate Theses, Dissertations, and Problem Reports (ETD)

We catalog the ubiquity of Radio Frequency Interference (RFI) plaguing every modern radio telescope and investigate several ways to mitigate it in order to create better science-ready data products for astronomers. There are a myriad of possible RFI sources, including satellite uplinks and downlinks, cellular communications, air traffic radar, and natural sources such as lightning. Real-time RFI mitigation strategies must take these RFI characteristics into account, as the interfering signals can look significantly different at very high time and frequency resolutions.

We examine Spectral Kurtosis (SK) as a real-time statistical RFI detection method, and compare its flagging efficacy against simulated …

Information Entropic Content Of Astrophysical Spectra: Applications To Cosmology And Astrobiology, Sara Vannah

Dartmouth College Ph.D Dissertations

Astrophysics faces two critical challenges: the difficulty of observing very distant targets and the difficulty of interpreting science in diverse and often extreme environments that have not been replicated on Earth. In this thesis, we discuss two types of spectra — one from early universe cosmology and one from astrobiology — where improvements in telescope technology are just ushering in a wave of precise observations, addressing the first challenge. This accelerates the need for a solution to the second challenge. Traditional methods for analyzing these two spectra rely heavily on unsettled science, biasing results to match the input assumptions. In …

Milky Way Morphology Probed By 6d Astrometric Data From The Gaia Space Telescope, Joshua Taylor Harry

Theses and Dissertations--Physics and Astronomy

At varying height above and below the plane of the Milky Way, I have used astrometric methods to classify stars of different galactic components of the Milky Way - the thin disk, thick disk, and stellar halo. This work complements prior study of Milky Way sub-structure - notably involving number density and/or pairwise correlations - which demonstrate non-steady state effects in the galaxy, such as axial/north-south symmetry breaking or more complex phenomena like the Gaia snail. This has motivated my exploration of stellar population changes with height about the Milky Way mid-plane, and the study of symmetry in such changes …

Understanding The Physics Of Galaxy Clusters Out To Their Virial Radii And Beyond, Arnab Sarkar

Theses and Dissertations--Physics and Astronomy

In the hierarchical structure formation model, galaxy clusters grow and evolve via mergers and accretion from the surrounding cosmic web, leaving distinctive marks in the gas properties, metallicity, and dynamical state at the outskirts of clusters, which needs to be probed to better understand the growth of a cluster. I probed the gas properties of four nearby galaxy groups MKW4, Antlia, RXJ1159, and ESO3060170 out to their virial radii using deep Suzaku and mostly snapshot Chandra observations. I found the gas entropy profiles of MKW4 follow a power-law at its outskirts - as expected from purely gravitational structure formation model. …

Constraining The Star Formation Histories Of Galaxies In The Swift/Uvot + Manga (Swim) Value-Added Catalog, Nikhil Ajgaonkar

Theses and Dissertations--Physics and Astronomy

Although our understanding about galaxy evolution has improved in the past few
decades, we still do not understand how galaxies suddenly stop forming stars and move towards a quiescent phase. In order to do that, we must derive the Star Formation Histories (SFHs) of galaxies, that trace the change in Star Formation (SF) inside the galaxy over the cosmic timescale. This is achieved by using a set of spatially resolved near-ultraviolet (NUV) and optical spectroscopic images of the galaxies. We generate the Swift/UVOT + MaNGA value added catalog (SwiM VAC; Molina et al., 2020b) which comprises 150 galaxies having a …

Newgrange Skyscape In Stellarium, Frank Prendergast

Articles

Newgrange Skyscape in Stellarium is a new customised landscape planetarium model giving the user the unique ability to interrogate the dynamic sky above the Boyne Valley on any date of interest during the hours of daylight or darkness. Archaeological, astronomical and topographical points of interest are labelled in the model and visible even during the hours of darkness. These are summarily described in a short gazetteer appended at the end of the instruction document to encourage further exploration of the wonderful heritage found in the Boyne Valley and beyond.

Watch on Youtube: https://www.youtube.com/watch?app=desktop&v=aGPsVGBXkY4

Watch on Vimeo: https://vimeo.com/493351576

Modeling Cherenkov Light Detection Timing For The Very Energetic Radiation Imaging Telescope Array System, Keilan Finn Ramirez

Physics

The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12-meter telescopes which use the Imaging Atmospheric Cherenkov Technique to conduct high-energy gamma-ray astronomy. VERITAS detects magnitude and location information associated with Cherenkov light, and uses this information to indirectly observe gamma-rays through a software reconstruction process. VERITAS also records timing information corresponding to Cherenkov light detection, and this additional information could theoretically be incorporated into the reconstruction process to improve the accuracy of gamma-ray observations. The first step to including timing information is to understand when Cherenkov light detection would be expected from a known …

Analysis Of Titan's Fluvial Features Using Numerical Modeling, Jeshurun Horton

Mechanical Engineering Undergraduate Honors Theses

River channels have been observed near the Huygens probe landing site on the surface of Titan, along with evidence of rounded water ice boulders transported through fluid flow. Evidence near the landing site suggests active flow of liquid methane, which has motivated the study of the effects of sediment load and channel sizes on Titan’s fluvial features. A numerical model is used to determine the viscosity, flow velocity, and critical boulder transport diameter based on channel size, slope, and a range of sediment concentrations. This model achieves two ends: first, observed boulder diameters are used to determine the ideal channel …

On The Mobility Of Small Aperture Telescopes For Initial Orbit Determination And Apparent Magnitude Derivation Of Low Earth Satellites, Jonathan Ian Hernandez

Master's Theses

Maintaining Space Domain Awareness (SDA) of satellites in low Earth orbit (LEO) requires effective methods of tracking and characterization. Optical measurements of these objects are generally sparse due to limited access intervals and high angular rates. Light pollution and geographic obstructions may also preclude consistent observations. However, a mobile small aperture telescope grants the ability to minimize such environmental effects, thereby increasing capture likelihoods for objects within this regime. By enhancing LEO satellite visibility in this way, extensive orbital and visual data are obtainable.

An 8-inch Meade LX200GPS telescope equipped with a Lumenera SKYnyx2-0M CCD camera comprises the system that …

Dark Matter Detection Materials, James E. Harrison Iv

PANDION: The Osprey Journal of Research and Ideas

The purpose of this paper is to review the different methods and materials used in the detection of dark matter. Special attention is given to materials in the solid state, but other materials are briefly mentioned for the sake of completeness. After a review, we discuss the viability of each material as a detector, and determine what advantages each material has, and what method of detection works best for each material. We conclude by discussing the potential outcomes of a null detection.

Using Methanol Masers To Probe High Mass Star Forming Regions, Naomi S. Shechter, Anuj P. Sarma

DePaul Discoveries

Compared to low mass stars, the formation of high mass stars is not well understood. To understand better how high mass stars form, we can utilize masers, naturally amplified point sources of microwave radiation. One example is the methanol maser, which falls into two categories. Class I methanol masers form in the bipolar outflows from the protostar, and Class II masers form in the accretion disk. Their compact size and intensity make them an excellent source of information about the process of high mass star formation. We compiled a modest database of Class I and II methanol masers through a …

Energy Requirements For Abiotic Production Of Phosphorous Compounds At The Ice-Schreibersite Interface, Lindsay M. Hicks

Symposium of Student Scholars

Energy Requirements for Abiotic Production of Phosphorous Compounds at the

Ice-Schreibersite Interface

The Abbott-Lyon Lab is investigating the chemistry at the interface of simple ices and a meteoritic mineral analogue. Phosphorous is a key component of numerous biomolecules necessary for life. Lack of an abundance of biologically accessible mineral sources of phosphates on Earth, termed “The Phosphorous Problem,” has led some origin-of-life scientists to look to extraterrestrial sources like meteoritic metal phosphides as possible sources of available phosphates. Schreibersite (Fe₂NiP) is a common mineral in iron meteorites and a plausible source of biologically accessible phosphorous. This study will …

Photochemistry Of Nh2No2 And Implications For Chemistry In The Atmosphere, Vincent J. Esposito, Tarek Trabelsi, Joseph S. Francisco

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Recent studies have indicated that nitramide (NH₂NO₂) may be formed more plentifully in the atmosphere than previously thought, while also being a missing source of the greenhouse gas nitrous oxide (N₂O) via catalyzed isomerization. To validate the importance of NH₂NO₂ in the Earth’s atmosphere, the ground and first electronic excited states of NH₂NO₂ were characterized and its photochemistry was investigated using multireference and coupled cluster methods. NH₂NO₂ is non-planar and of singlet multiplicity in the ground state while exhibiting large out-of-plane rotation in the triplet …

Spectroscopic Analysis Of Potential Astromolecules Via Quantum Chemical Quartic Force Fields, Mason Gardner

Honors Theses

Astrochemistry has been substantially aided by computational techniques, particularly through the use of Quartic Force Field (QFF) analysis. Several methods have proven useful at correlating computed spectroscopic data with experimental observations. The F12-TZ QFF correlated well with experimental data for silicon oxide compounds, particularly those potentially involved in development from rocky bodies to planetary masses [27]. Compared to argon matrix experimental data, the vibrational frequencies for the molecules SiO2, SiO3, Si2O3, and Si2O4 become less accurate as the complexity of the molecules increases but should still be predictive of infrared characteristics of silicon oxides as they form clusters in space …

Variable Nature Of Accretion Disk Outflows Around Supermassive Black Holes In Active Galaxies, Mary Ogborn

Senior Honors Projects, 2020-current

Seyfert galaxies are a sub-class of active galactic nuclei (AGNs) in which outflows are ubiquitously observed and thought to be produced from accretion disks surrounding supermassive black holes (SMBHs). These outflows manifest themselves as blueshifted absorption features in their X-Ray spectra (aka. warm absorbers (WAs)), allowing for spectroscopic analysis to examine the physical conditions of the constituent plasma as well as the AGN itself. In the context of magnetohydrodynamics (MHD), we utilize a magnetically-driven disk-wind model that describes the behavior within the disk and to study 3 exemplary Seyfert 1 AGNs in an effort to constrain the strength of the …

Snore: An Intuitive Algorithm For Accurately Simulating N-Body Orbits, Connor L. Nance

Honors College Theses

We present SnOrE (Simple n-body Orbital Engine), a Python package which aims to simulate n-body orbital systems while simultaneously overcoming early educational barriers of computational astrodynamics for undergraduate physics students. SnOrE exploits rudimentary syntax and commonly-understood Python libraries to accurately simulate orbits of systems, given initial position and momentum conditions of each body in the system. As the n-body problem is as of yet unsolvable theoretically for n ≥ 3, having a numerical perspective on complicated orbits is of great importance to potentially understanding the processes of star and planet formation. Especially significant examples of this research …

382— Wiyn Open Cluster Study: Ubvri Photometry Of Ngc 2204, Kylie Snyder, Dante Scarazzini

GREAT Day Posters

The purpose of this project was to study the open star cluster NGC2204 using images taken at Kitt Peak National Observatory using the WIYN 0.9m telescope. These images were analyzed photometrically with the intention of determining the reddening, metallicity, age, and distance modulus of the star cluster. Each image was analyzed using software that determined the point spread function and applied that function to determine the magnitude of each star in that image. These magnitudes were taken for each filter, UBVRI, and then combined and averaged to create a single catalog. Standard stars, taken on the same night, were used …

A Detailed X-Ray Analysis Of The Cold Front In Relics Cluster A2163, Anne Poy

CMC Senior Theses

Galaxy clusters are the largest gravitationally bound objects in the Universe. Studying them can teach us about how they merge and grow, which in turn provides unparalleled information about the history of the evolution of the Universe. X-ray observations of galaxy clusters have uncovered substructure in the hot, X-ray emitting gas known as the intracluster mediums (ICM). Substructure indicates that the ICM has been churned up, possibly by a significant off-axis merger event. This substructure includes cold fronts, sloshing spirals, and shocks. We present deep Chandra observations of the merging cluster Abell 2163. We investigate the global spectrum and find …

Searching Harder, Localizing Better, Classifying Faster: Optimizing Fast Radio Burst Detection And Analysis, Kshitij Aggarwal

Graduate Theses, Dissertations, and Problem Reports (ETD)

Fast Radio Bursts (or FRBs) are millisecond-duration transients of extragalactic origin. They exhibit dispersion caused by propagation through an ionized medium, and quantified by Dispersion Measure (DM). Around 800 FRBs (24 repeaters) have been discovered; so far, 24 FRBs have been confidently associated with a host galaxy. In this thesis, we discuss multiple new FRB search and analysis techniques and the corresponding tools that enable us to search for FRBs harder, localize them better, and classify candidates faster.

We discuss five open-source software suites that can be used in FRB analysis. These suites are used to distinguish between FRBs and …