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Articles 1 - 30 of 116
Full-Text Articles in Astrophysics and Astronomy
Cosmic Chirps: Studies In The Evolution And Detection Of Gravitational Waves From Compact Binary Systems, Calla Irene Bassett Bigg
Cosmic Chirps: Studies In The Evolution And Detection Of Gravitational Waves From Compact Binary Systems, Calla Irene Bassett Bigg
Graduate Theses and Dissertations
This dissertation will go over three projects that have to do with gravitational wave mechanics and history. The first project is about investigating computationally cheaper approximation methods for modeling EMRI (extreme mass ratio inspiral) orbits using interpolation. Two codes are interpolated together for full coverage of the parameter space. This interpolation has yet to be tested for accuracy but the preliminary outlook is positive. This may well be a useful tool for studying EMRIs. The second project is investigating the origins of the term “chirp mass”, where chirp mass is a combination of the two masses in a binary that …
Modeling Hot Jupiter Atmospheres For The Classification Of Low Abundance Molecules, Mika Brown
Modeling Hot Jupiter Atmospheres For The Classification Of Low Abundance Molecules, Mika Brown
Physics Undergraduate Honors Theses
Transmission spectroscopy is a powerful method for studying exoplanet atmospheres. With the recent launch of the James Webb Space Telescope (JWST), several molecules have been successfully detected in hot Jupiter atmospheres at an unprecedented level of precision with transmission spectroscopy. To better understand current detection capabilities and limitations, this project used machine learning techniques to determine which molecules are currently identifiable at the spectral resolution and wavelength range of JWST’s NIRSpec instrument in PRISM mode. A large synthetic dataset of transmission spectra was first generated using the petitRADTRANS radiative transfer Python package. The resulting spectra were then used to train …
Can Methanogens Grow On Asteroids?, Isabella N. Reimer
Can Methanogens Grow On Asteroids?, Isabella N. Reimer
Biological Sciences Undergraduate Honors Theses
Because of asteroids’ chemical features, they may serve as potential environments for life and are of interest in astrobiology. Dr. Kral’s laboratory studies methanogens, microorganisms in the domain Archaea, as possible life forms on extraterrestrial bodies. Since some methanogens can withstand harsh environmental conditions and produce methane as a waste product, methane production can be used as an indicator of potential microbial activity. In this study, three methanogen species, Methanothermobacter wolfeii, Methanobacterium formicicum, and Methanosarcina barkeri were tested for growth on asteroid simulants based on the Orgueil (CIE-1) and Murchison (CME-1) meteorites. First, methanogen growth was assessed in the …
Of Dunes And Ice: A Surface-Atmosphere Investigation Of Mars Co2 Sublimation Features And Titan Aeolian Fields, Racine D. Cleveland
Of Dunes And Ice: A Surface-Atmosphere Investigation Of Mars Co2 Sublimation Features And Titan Aeolian Fields, Racine D. Cleveland
Graduate Theses and Dissertations
This dissertation investigates a central question: How do planetary boundary layer processes manifest in observable surface geomorphology, and how can planetary imagery be used to quantify those effects? The planetary boundary layer (PBL) governs near-surface exchanges of momentum, heat, and volatiles, yet direct atmospheric measurements remain spatially and temporally limited on most planetary bodies. By analyzing geomorphic features preserved in high-resolution imagery, this work quantifies how boundary-layer processes leave measurable signatures on planetary surfaces. For Mars, high-resolution images from the Mars Reconnaissance Orbiter (MRO) HiRISE instrument were used to map CO2 sublimation features, or Swiss Cheese Features (SCFs), on the …
Characterizing Stellar Flares On Low-Mass Stars Tic 144217628 And Proxima Centauri Using Transiting Exoplanet Space Satellite (Tess) Optical Data, Charles Edward Holloway
Characterizing Stellar Flares On Low-Mass Stars Tic 144217628 And Proxima Centauri Using Transiting Exoplanet Space Satellite (Tess) Optical Data, Charles Edward Holloway
Graduate Theses and Dissertations
Low-mass stars account for more than 70% of stars within our galaxy. Their ob?servational interest can be attributed to their smaller radius and luminosity, making them ideal for detecting terrestrial planets inside their habitable zones. These magnetically active stars produce frequent stellar flaring events that can impact the atmospheric composition of nearby planets and interfere with the prebiotic processes for carbon-based life. Using TESS optical data, I have detected, measured astrophysical properties, and modeled the behavior of 44 flares from two low-mass stars: TIC 144217628 and Proxima Centuari. Given similar observational periods, Proxima Cen has shown to produce larger amplitudes …
Temperature, Albedo, And Emissivity Of Triton And Proteus From Voyager 2 Iris Data, Garrett Nobis, Vincent Chevrier
Temperature, Albedo, And Emissivity Of Triton And Proteus From Voyager 2 Iris Data, Garrett Nobis, Vincent Chevrier
Space and Planetary Science Faculty Publications and Presentations
The Voyager 2 infrared interferometer and spectrometer (IRIS) spectra for Triton are revisited, and the Proteus IRIS spectra are looked at for the first time. Fifty more spectra are added to the average of 16 previously used for Triton. The unit emissivity Planck function temperature result is 37.9 ± 0.5 K. Iterating IRIS temperatures over several emissivities allows for constraints on emissivity and Bond albedo based on past data. Upper and lower bounds on Triton’s temperature and albedo of 37.9 ± 0.5 to 46.1 ± 0.7 K for temperature and 0.67−0.86 for albedo are determined from the IRIS data and …
Constraining Neutron Star Kicks Through Gravitational Wave Detection, James Phillips
Constraining Neutron Star Kicks Through Gravitational Wave Detection, James Phillips
Graduate Theses and Dissertations
Neutron stars have, on average, much higher proper motions than those of hot and bright O and B type main sequence stars. Thus, it is widely suspected that asymmetries in core-collapse supernovae provide a substantial kick to these compact objects at birth. Gen- eral Relativity predicts that such supernova asymmetries will generate bursts of gravitational radiation, though no such burst has been yet detected. Here we argue that the polarization amplitudes of those gravitational waves can be used to calculate the kicks imparted on that nascent neutron star. We begin by reviewing the evidence for natal kicks, then we describe …
The Elusive Nature Of Martian Liquid Brines, Vincent F. Chevrier, Rachel A. Slank
The Elusive Nature Of Martian Liquid Brines, Vincent F. Chevrier, Rachel A. Slank
Space and Planetary Science Faculty Publications and Presentations
The possible presence of brines on Mars adds an intriguing dimension to the exploration of Martian environments. Their potential involvement in the formation of recurring slope lineae has sparked debates on the existence of liquid water versus alternative dry processes. In situ instrumentation on rovers and landers has been instrumental in providing valuable data for comprehending the dynamics of brines. Laboratory experiments and thermodynamic simulations conducted under Martian conditions offer insights into the formation and persistence of brines, shedding light on the planet’s current hydrological processes. Despite these findings, the prevailing surface conditions on Mars, characterized by a combination of …
An Empirical Framework Characterizing The Metallicity And Star-Formation History Dependence Of X-Ray Binary Population Formation And Emission In Galaxies, Bret D. Lehmer, Erik B. Monson, Rafael T. Eufrasio, Amirnezam Amiri, Keith Doore, Antara Basu-Zych, Kristen Garofali, Lidia Oskinova, Jeff J. Andrews, Vallia Antoniou, Robel Geda, Jenny E. Greene, Konstantinos Kovlakas, Margaret Lazzarini, Chris T. Richardson
An Empirical Framework Characterizing The Metallicity And Star-Formation History Dependence Of X-Ray Binary Population Formation And Emission In Galaxies, Bret D. Lehmer, Erik B. Monson, Rafael T. Eufrasio, Amirnezam Amiri, Keith Doore, Antara Basu-Zych, Kristen Garofali, Lidia Oskinova, Jeff J. Andrews, Vallia Antoniou, Robel Geda, Jenny E. Greene, Konstantinos Kovlakas, Margaret Lazzarini, Chris T. Richardson
Physics Faculty Publications and Presentations
We present a new empirical framework modeling the metallicity and star formation history (SFH) dependence of X-ray luminous (L ≳ 1036 erg s−1) point-source population X-ray luminosity functions (XLFs) in normal galaxies. We expect that the X-ray point-source populations are dominated by X-ray binaries (XRBs), with contributions from supernova remnants near the low luminosity end of our observations. Our framework is calibrated using the collective statistical power of 3731 X-ray detected point sources within 88 Chandra-observed galaxies at D ≲ 40 Mpc that span broad ranges of metallicity (Z ≈ 0.03–2 Z⊙), SFH, …
A Nustar Census Of The X-Ray Binary Population Of The M31 Disk, Hannah Moon, Daniel Wik, V. Antoniou, M. Eracleous, Ann Hornschemeier, Margaret Lazzarini, Bret D. Lehmer, Neven Vulic, Benjamin F. Williams, T. J. Maccarone, K. Pottschmidt, Andrew Ptak, Mihoko Yukita, Andreas Zezas
A Nustar Census Of The X-Ray Binary Population Of The M31 Disk, Hannah Moon, Daniel Wik, V. Antoniou, M. Eracleous, Ann Hornschemeier, Margaret Lazzarini, Bret D. Lehmer, Neven Vulic, Benjamin F. Williams, T. J. Maccarone, K. Pottschmidt, Andrew Ptak, Mihoko Yukita, Andreas Zezas
Physics Faculty Publications and Presentations
Using hard (E > 10 keV) X-ray observations with NuSTAR, we are able to differentiate between the accretion states, and thus compact object types, of neutron stars (NSs) and black holes (BHs) in X-ray binaries (XRBs) in M31, our nearest Milky Way–type neighbor. Using 10 moderate-depth (20–50 ks) observations of the disk of M31 covering a total of ∼0.45 deg2, we detect 20 sources at 2σ in the 4–25 keV bandpass, 14 of which we consider to be XRB candidates. This complements an existing, deeper (100–400 ks) survey covering ∼0.2 deg2 of the bulge and the …
A Search For Pulsars And An Exploration Of Dispersion Measure Within The Milky Way Galaxy, Emily Ware
A Search For Pulsars And An Exploration Of Dispersion Measure Within The Milky Way Galaxy, Emily Ware
Physics Undergraduate Honors Theses
A pulsar is a rapidly rotating neutron star which emits electromagnetic radiation from its magnetic poles. Upon detection from Earth, these signals have been dispersed in phase due to electron interactions in transit. The extent of this dispersion indicates information about both the distance to and the location of the pulsar, with respect to Earth and the Galactic plane. This project makes use of radio data from the 100m Robert C. Byrd Green Bank Telescope (GBT), presented in the form of prepfold plots assembled by the Pulsar Science Collaboratory (PSC). 1,007 of these plots were analyzed in order to determine …
Survival Of Methanogens Desiccated On Mars Soil Simulants: Implications For Life On Mars, Lanee Knight
Survival Of Methanogens Desiccated On Mars Soil Simulants: Implications For Life On Mars, Lanee Knight
Biological Sciences Undergraduate Honors Theses
Because of Mars’s chemical features, it can be studied in the search for life and is a significant figure in the study of astrobiology (McKay, 2010). Dr. Kral’s laboratory studies methanogens, microorganisms in the domain Archaea, as possible life forms on Mars. Since some methanogens can withstand harsh environmental conditions and emit methane as a waste product, the growth of these microorganisms can be used as an indicator of potential life in the Mars subsurface (Kral et al., 1998). In this research, four methanogens, Methanothermobacter wolfeii, Methanobacterium formicicum, Methanosarcina barkeri, and Methanococcus maripaludi were desiccated in the …
Spin Disorder Control Of Topological Spin Texture, Hongrui Zhang, Yu-Tsun Shao, Xiang Chen, Binhua Zhang, Tianye Wang, Fanhao Meng, Kun Xu, Peter Meisenheimer, Xianzhe Chen, Xiaoxi Huang, Piush Behera, Sajid Husain, Tiancong Zhu, Hao Pan, Yanli Jia, Nick Settineri, Nathan Giles-Donovan, Zehao He, Andreas Scholl, Alpha N'Diaye, Padraic Shafer, Archana Raja, Changsong Xu, Lane W. Martin, Michael F. Crommie, Jie Yao, Ziqiang Qiu, Arun Majumdar, Laurent Bellaiche, David A. Muller, Robert J. Birgeneau, Ramamoorthy Ramesh
Spin Disorder Control Of Topological Spin Texture, Hongrui Zhang, Yu-Tsun Shao, Xiang Chen, Binhua Zhang, Tianye Wang, Fanhao Meng, Kun Xu, Peter Meisenheimer, Xianzhe Chen, Xiaoxi Huang, Piush Behera, Sajid Husain, Tiancong Zhu, Hao Pan, Yanli Jia, Nick Settineri, Nathan Giles-Donovan, Zehao He, Andreas Scholl, Alpha N'Diaye, Padraic Shafer, Archana Raja, Changsong Xu, Lane W. Martin, Michael F. Crommie, Jie Yao, Ziqiang Qiu, Arun Majumdar, Laurent Bellaiche, David A. Muller, Robert J. Birgeneau, Ramamoorthy Ramesh
Physics Faculty Publications and Presentations
Stabilization of topological spin textures in layered magnets has the potential to drive the development of advanced low-dimensional spintronics devices. However, achieving reliable and flexible manipulation of the topological spin textures beyond skyrmion in a two-dimensional magnet system remains challenging. Here, we demonstrate the introduction of magnetic iron atoms between the van der Waals gap of a layered magnet, Fe3GaTe2, to modify local anisotropic magnetic interactions. Consequently, we present direct observations of the order-disorder skyrmion lattices transition. In addition, non-trivial topological solitons, such as skyrmioniums and skyrmion bags, are realized at room temperature. Our work highlights …
Algorithm-Based Linearly Graded Compositions Of Gesn On Gaas (001) Via Molecular Beam Epitaxy, Calbi Gunder, Mohammad Zamani-Alavijeh, Emmanuel Wangila, Fernando Maia De Oliveira, Aida Sheibani, Serhii Kryvyi, Paul C. Attwood, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo
Algorithm-Based Linearly Graded Compositions Of Gesn On Gaas (001) Via Molecular Beam Epitaxy, Calbi Gunder, Mohammad Zamani-Alavijeh, Emmanuel Wangila, Fernando Maia De Oliveira, Aida Sheibani, Serhii Kryvyi, Paul C. Attwood, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo
Physics Faculty Publications and Presentations
The growth of high-composition GeSn films in the future will likely be guided by algorithms. In this study, we show how a logarithmic-based algorithm can be used to obtain high-quality GeSn compositions up to 16% on GaAs (001) substrates via molecular beam epitaxy. Herein, we use composition targeting and logarithmic Sn cell temperature control to achieve linearly graded pseudomorph Ge1−xSnx compositions up to 10% before partial relaxation of the structure and a continued gradient up to 16% GeSn. In this report, we use X-ray diffraction, simulation, secondary ion mass spectrometry, and atomic force microscopy to analyze and …
The Gravitational Wave Peep: Improved Modeling Of Highly Eccentric Emris For Lisa Signal Confusion Noise, Daniel Joseph Oliver
The Gravitational Wave Peep: Improved Modeling Of Highly Eccentric Emris For Lisa Signal Confusion Noise, Daniel Joseph Oliver
Graduate Theses and Dissertations
Scattering events around a massive black hole will occasionally toss a stellar-mass compact object into an orbit around the massive black hole, beginning an extreme mass ratio inspiral. The early stages of such a highly eccentric orbit will not produce detectable gravitational waves as the source will only be in a suitable frequency band briefly when it is close to periapsis during each long-period orbit. This burst of emission, firmly in the millihertz band, is the gravitational wave peep. While a single peep is not likely to be detectable, if we consider an ensemble of such subthreshold sources, spread across …
Group Iv Topological Quantum Alloy And The Role Of Short-Range Order: The Case Of Ge-Rich Ge1–XPbX, Yunfan Liang, Shunda Chen, Xiaochen Jin, Damien West, Shui-Qing Yu, Tianshu Li, Shengbai Zhang
Group Iv Topological Quantum Alloy And The Role Of Short-Range Order: The Case Of Ge-Rich Ge1–XPbX, Yunfan Liang, Shunda Chen, Xiaochen Jin, Damien West, Shui-Qing Yu, Tianshu Li, Shengbai Zhang
Electrical Engineering and Computer Science Faculty Publications and Presentations
Despite the explosion of interest in topological materials over the last decades, their applications remain limited due to challenges in growth and incorporation with today’s microelectronics. As a potential bridge to close this gap, we investigate the group-IV alloy Ge1–xPbx, in the Ge-rich condition using density functional theory and show that relatively low concentrations of Pb (~9.4%) can lead to a topological phase transition. Furthermore, the calculation of the Z2 invariant for both the random alloy and the alloy with short-range order (SRO) indicate that the topological phase of the material can be directly modified …
Detection Of Dsrab Operon Expression In Desulfotalea Psychrophila Cells Subjected To Simulated Martian Conditions Of Temperature And Regolith's Sulphate Minerals Composition, Sergio Mosquera, Mack Ivey, Vincent F. Chevrier
Detection Of Dsrab Operon Expression In Desulfotalea Psychrophila Cells Subjected To Simulated Martian Conditions Of Temperature And Regolith's Sulphate Minerals Composition, Sergio Mosquera, Mack Ivey, Vincent F. Chevrier
Biological Sciences Faculty Publications and Presentations
Discoveries of transient liquid water in the Martian polar caps and the presence of liquid lakes and subsurface oceans in icy satellites have increased the interest of scientists in the capabilities of terrestrial extremophiles to grow and remain metabolically active in these extreme environments. The principal goal of this research is to understand the metabolic capacity of the anaerobic psychrophile, Desulfotalea psychrophila, cultured at subfreezing temperatures in media containing various concentrations of sulphate minerals. In this regard, our experiments focused on the detection of D. psychrophila survival and active metabolism, employing a biochamber that can recreate Martian temperatures. Using …
The High Energy X-Ray Probe: Resolved X-Ray Populations In Extragalactic Environments, Bret D. Lehmer, Kristen Garofali, Breanna A. Binder, Francesca Fornasini, Neven Vulic, Andreas Zezas, Ann Hornschemeier, Margaret Lazzarini, Hannah Moon, Toni Venters, Daniel Wik, Mihoko Yukita, Matteo Bachetti, Javier A. Garcia, Brian Grefenstette, Kristin Madsen, Kaya Mori, Daniel Stern
The High Energy X-Ray Probe: Resolved X-Ray Populations In Extragalactic Environments, Bret D. Lehmer, Kristen Garofali, Breanna A. Binder, Francesca Fornasini, Neven Vulic, Andreas Zezas, Ann Hornschemeier, Margaret Lazzarini, Hannah Moon, Toni Venters, Daniel Wik, Mihoko Yukita, Matteo Bachetti, Javier A. Garcia, Brian Grefenstette, Kristin Madsen, Kaya Mori, Daniel Stern
Physics Faculty Publications and Presentations
We construct simulated galaxy data sets based on the High Energy X-ray Probe (HEX-P) mission concept to demonstrate the significant advances in galaxy science that will be yielded by the HEX-P observatory. The combination of high spatial resolution imaging (FWHM), broad spectral coverage (0.2–80 keV), and sensitivity superior to current facilities (e.g., XMM-Newton and NuSTAR) will enable HEX-P to detect hard (4–25 keV) X-ray emission from resolved point-source populations within ∼800 galaxies and integrated emission from ∼6,000 galaxies out to 100 Mpc. These galaxies cover wide ranges of galaxy types (e.g., normal, starburst, and passive galaxies) and properties (e.g., metallicities …
Revisiting The Properties Of X-Ray Active Galactic Nuclei In The Ssa22 Protocluster: Normal Supermassive Black Hole And Host-Galaxy Growth For Agns In A Z=3.09 Overdensity, Erik B. Monson, Keith Doore, Rafael T. Eufrasio, Bret D. Lehmer, David M. Alexander, Chris M. Harrison, Mariko Kubo, Cristian Saez, Hideki Umehata
Revisiting The Properties Of X-Ray Active Galactic Nuclei In The Ssa22 Protocluster: Normal Supermassive Black Hole And Host-Galaxy Growth For Agns In A Z=3.09 Overdensity, Erik B. Monson, Keith Doore, Rafael T. Eufrasio, Bret D. Lehmer, David M. Alexander, Chris M. Harrison, Mariko Kubo, Cristian Saez, Hideki Umehata
Physics Faculty Publications and Presentations
We analyze the physical properties of eight X-ray-selected active galactic nuclei (AGNs) and one candidate protoquasar system (ADF22A1) in the z = 3.09 SSA22 protocluster by fitting their X-ray-to-IR spectral energy distributions (SEDs) using our SED-fitting code, Lightning (https://www.github.com/rafaeleufrasio/lightning). We recover star formation histories (SFHs) for seven of these systems which are well fit by composite stellar population plus AGN models. We find indications that four out of nine of the SSA22 AGN systems we study have host galaxies below the main sequence, with SFR/SFRMS ≤ −0.4. The remaining SSA22 systems, including ADF22A1, are consistent with obscured supermassive black hole …
The Large Deficit Of Hmxb Emission From Luminous Infrared Galaxies: The Case Of The Circumnuclear Starburst Ring In Ngc 7552, Lacey West, Kristen Garofali, Bret D. Lehmer, Andrea Prestwich, Rafael Eufrasio, Wasutep Luangtip, Timothy P. Roberts, Andreas Zezas
The Large Deficit Of Hmxb Emission From Luminous Infrared Galaxies: The Case Of The Circumnuclear Starburst Ring In Ngc 7552, Lacey West, Kristen Garofali, Bret D. Lehmer, Andrea Prestwich, Rafael Eufrasio, Wasutep Luangtip, Timothy P. Roberts, Andreas Zezas
Physics Faculty Publications and Presentations
Luminous infrared galaxies (LIRGs), the most extreme star-forming galaxies in the nearby (D < 30 Mpc) universe, show a notable X-ray emission deficiency (up to a factor of ∼10) compared with predictions from scaling relations of galaxy-wide high-mass X-ray binary (HMXB) luminosity with star formation rate. In the nearby (≈20 Mpc) LIRG NGC 7552, the majority of the IR emission originates in a circumnuclear starburst ring, which has been resolved into several discrete knots of star formation. We present results from recent Chandra observations of NGC 7552, which reveal significant deficits in the 2–7 keV X-ray luminosities from two of the most powerful star-forming knots. We hypothesize that the expected luminous HMXB populations in these knots are either (1) obscured by very large column densities or (2) suppressed due to the knots having relatively high metallicity and/or very young ages (≲5 Myr). We distinguish between these possibilities using data from recent NuSTAR observations, whose sensitivity above 10 keV is capable of uncovering heavily obscured HMXB populations, since emission at these energies is more immune to absorption effects. We find no evidence of a heavily obscured HMXB population in the central region of NGC 7552, suggesting suppressed HMXB formation. We further show that metallicity-dependent scaling relations cannot fully account for the observed deficit from the most powerful star-forming knots or the central region as a whole. Thus, we suggest that recent bursts in local star formation activity likely drive the high LIR within these regions on timescales ≲5 Myr, shorter than the timescale required for the formation of HMXBs.
Lightning: An X-Ray To Submillimeter Galaxy Sed-Fitting Code With Physically Motivated Stellar, Dust, And Agn Models, Keith Doore, Erik B. Monson, Rafael T. Eufrasio, Bret D. Lehmer, Kristen Garofali, Antara Basu-Zych
Lightning: An X-Ray To Submillimeter Galaxy Sed-Fitting Code With Physically Motivated Stellar, Dust, And Agn Models, Keith Doore, Erik B. Monson, Rafael T. Eufrasio, Bret D. Lehmer, Kristen Garofali, Antara Basu-Zych
Physics Faculty Publications and Presentations
We present an updated version of Lightning, a galaxy spectral energy distribution (SED) fitting code that can model X-ray to submillimeter observations. The models in Lightning include the options to contain contributions from stellar populations, dust attenuation and emission, and active galactic nuclei (AGNs). X-ray emission, when utilized, can be modeled as originating from stellar compact binary populations with the option to include emission from AGNs. We have also included a variety of algorithms to fit the models to observations and sample parameter posteriors; these include adaptive Markov Chain Monte Carlo (MCMC), affine-invariant MCMC, and Levenberg–Marquardt gradient-descent (MPFIT) algorithms. To …
Analysis On High Mass X-Ray Binary Spectral Shape Dependence On Luminosity For Ngc3310, Izabela Pavel
Analysis On High Mass X-Ray Binary Spectral Shape Dependence On Luminosity For Ngc3310, Izabela Pavel
Physics Undergraduate Honors Theses
In most normal galaxies, the most X-ray luminous sources are high-mass X-ray binaries (HMXBs), which are binary star systems that contain compact objects (black holes or neutron stars) accreting from massive (> 8M⊙) companion stars. These HMXBs are thought to have been important sources of ionizing emission within star-forming galaxies that may have contributed to the heating of the intergalatic medium (gas over large cosmic scales) in the early Universe. When studying how HMXBs contribute to interstellar medium feedback, a single spectral shape of an absorbed power-law is typically assumed to be universal. The goal of this thesis is to …
Insights Into Star Formation And Agn Activity In Protocluster Environments From Morphological Studies And Sed Fitting, Erik B. Monson
Insights Into Star Formation And Agn Activity In Protocluster Environments From Morphological Studies And Sed Fitting, Erik B. Monson
Graduate Theses and Dissertations
In this dissertation I present work done from 2018-2023 to investigate the growth of galaxies and supermassive black holes (SMBH) in high redshift overdensities (protoclusters) by studying the star-forming galaxy and active galactic nucleus (AGN) population in the SSA22 protocluster. I examined possible environmental sources of the enhanced star formation and AGN activity in the z = 3.09 SSA22 protocluster using Hubble WFC3 ∼ 1.6 μm observations of the SSA22 field, including new observations centered on eight X-ray selected protocluster AGN. To investigate the role of mergers in the observed AGN and star formation enhancement, quantitative and visual morphological classifications …
On The Impact Of Inclination-Dependent Attenuation On The Derived Star Formation Histories Of Disk Galaxies, Keith Doore
On The Impact Of Inclination-Dependent Attenuation On The Derived Star Formation Histories Of Disk Galaxies, Keith Doore
Graduate Theses and Dissertations
The physical properties of a galaxy (e.g., its star-formation history and dust content) regulate the distribution of light that is emitted by stars and attenuated by the interstellar gas and dust. This attenuation by dust can have a significant impact on the observed spectral energy distribution (SED) of a disk galaxy, especially when taking into account its viewing angle (i.e., inclination). For example, as the inclination angle of a galactic disk changes from face-on to edge-on (i.e., i = 0 deg to i = 90 deg), the proportion of light that is attenuated along the line of sight increases, due …
Floating Liquid Droplets On The Surface Of Cryogenic Liquids: Implications For Titan Rain, Kendra Farnsworth, Alejandro Soto, Vincent F. Chevrier, Jordan K. Steckloff, Jason M. Soderblom
Floating Liquid Droplets On The Surface Of Cryogenic Liquids: Implications For Titan Rain, Kendra Farnsworth, Alejandro Soto, Vincent F. Chevrier, Jordan K. Steckloff, Jason M. Soderblom
Space and Planetary Science Faculty Publications and Presentations
Saturn’s moon, Titan, has a hydrocarbon-based hydrologic cycle with methane and ethane rainfall. Because of Titan’s low gravity, “floating liquid droplets” (coherent droplets of liquid hydrocarbons that float upon a liquid surface) may form on the surface of Titan’s hydrocarbon lakes and seas during rainfall. Floating liquid droplets, however, have not been investigated in the laboratory under conditions appropriate for the surface of Titan (cryogenic, hydrocarbon, liquids). We conducted a set of experiments to simulate methane and ethane rainfall under Titan surface conditions (89–94 K, 1.5 bar nitrogen atmosphere) and find that floating ethane droplets form in a wide range …
The Evolution Of X-Ray Binaries And Their Accretion States, Lacey A. West
The Evolution Of X-Ray Binaries And Their Accretion States, Lacey A. West
Graduate Theses and Dissertations
X-ray binary systems (XRBs) consist of a compact object component (e.g., black hole or neutron star) that accretes matter from a companion star. Although the extent to which XRBs contributed to the early heating of the intergalactic medium is still under investigation, it is estimated that XRBs dominated the X-ray radiation field before the reionization epoch. The study of XRB emission is therefore crucial to our understanding of the very early universe. Furthermore, studying the abundance and radial distribution of each XRB type within a galaxy can be revealing of the host galaxy’s local properties, structure, and evolution. XRB spectra …
First-Principles Study Of Doping Effects On Ferroelectricity And On Rashba Spin Splitting, Zegnet Yimer Muhammed
First-Principles Study Of Doping Effects On Ferroelectricity And On Rashba Spin Splitting, Zegnet Yimer Muhammed
Graduate Theses and Dissertations
In this dissertation, we have thoroughly studied the effect of chemical and charge dopingon ferroelectrics (PbTiO3 and BaTiO3) and Rashba type semiconductor (BiTeI). In the first project, We investigate the polar instability and soft modes in electron-doped PbTiO3 using linear-response density functional calculations. Because, metallicity and ferroelectric-like polar distortion are mutually non-compatible, and their coexistence in the same system is an intriguing subject of fundamental interest in the field of structure phase transition. However, it is unclear what mechanism may extend the limit of metallicity that allows polar distortion. We find that ferroelectric instability can remarkably sustain up to an …
A Method For Exploring The Habitability Of Earth-Like Exoplanets: Applications To Tess Objects Of Interest 203 B, 256 B, And 700 D, Paul Bonney
Graduate Theses and Dissertations
The Transiting Exoplanet Survey Satellite (TESS) has and is continuing to discover a multitude of potentially habitable planet candidates. As more planets are detected and confirmed, it becomes increasingly important to strategically search for signs of habitability with which to differentiate and prioritize them for further observation, in particular with the James Webb Space Telescope (JWST). To facilitate this, I have created a method for prioritizing TESS planet candidates based on parameters derived from their light curves and have applied the method to the TESS Candidate Target List (CTL). This data set uses preliminary fits to transit modeling which can …
Deciphering Surfaces Of Trans-Neptunian And Kuiper Belt Objects Using Radiative Scattering Models, Machine Learning, And Laboratory Experiments, Al Emran
Graduate Theses and Dissertations
Decoding surface-atmospheric interactions and volatile transport mechanisms on trans-Neptunian objects (TNOs) and Kuiper Belt objects (KBOs) involves an in-depth understanding of physical and thermal properties and spatial distribution of surface constituents – nitrogen (N2), methane (CH4), carbon monoxide (CO), and water (H2O) ices. This thesis implements a combination of radiative scattering models, machine learning techniques, and laboratory experiments to investigate the uncertainties in grain size estimation of ices, the spatial distribution of surface compositions on Pluto, and the thermal properties of volatiles found on TNOs and KBOs. Radiative scattering models (Mie theory and Hapke approximations) were used to compare single …
Orbital Mapping Of Seasonal And Yearly Changes In Co2 And Water Ice On The Southern Polar Cap Of Mars, Victoria Michell Ann Karnes
Orbital Mapping Of Seasonal And Yearly Changes In Co2 And Water Ice On The Southern Polar Cap Of Mars, Victoria Michell Ann Karnes
Graduate Theses and Dissertations
This research exhibits a new foundation for the rates of change in CO2 and water ice on the southern polar cap of Mars, where the annual precipitation cycles are known to fluctuate seasonally between the north and south pole, based on observations from the Compact Reconnaissance Imaging Spectrometer (CRISM). The conventional belief is that both CO2 ice and water ice on the southern polar cap condenses and evaporates over the course of a Martian year (MY), condensing during the Martian spring and summer and evaporating during the Martian fall and winter. With this theory in mind, CO2 and water ice …