Astrophysics and Astronomy Commons^™

Temporal And Spectral Analysis Of 1es 2344+514 In Two Flaring States Observed By Veritas, Connor Poggemann

Physics

VERITAS observed the bright blazar 1ES 2344+514 during two flaring periods, one from Dec. 17 to Dec. 18, 2015 (MJD 57373-57374) with a peak flux of ~60% of the Crab and another from Nov. 28 to Dec. 3, 2021 (MJD 59546-59551) with a peak flux of ~20% of the Crab. This blazar, located at a redshift of z = 0.044, is classified as an extreme high-frequency-peaked BL Lacertae object (HBL). It is known to be variable, including several previous day-scale flares: Whipple on Dec. 20, 1995, VERITAS on Dec. 7, 2007, and MAGIC on Aug. 11, 2016. The VERITAS near-nightly …

The Comprehensive Archive Of Substellar And Planetary Accretion Rates, S. K. Betti, K. B. Follette, K. Ward-Duong, A. E. Peck, Y. Aoyama, J. Bary, B. Dacus, S. Edwards, G. D. Marleau, K. Mohamed, J. Palmo, C. Plunkett, C. Robinson, H. Wang

Astronomy: Faculty Publications

Accretion rates ( M ̇ ) of young stars show a strong correlation with object mass (M); however, extension of the M ̇ - M relation into the substellar regime is less certain. Here, we present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest compilation to date of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the M ̇ - M relation and compare brown dwarfs to stars. In our analysis, we rederive all quantities …

First Vlti/Gravity Observations Of Hip 65426 B: Evidence For A Low Or Moderate Orbital Eccentricity, Sarah Blunt, W. O. Balmer, J. J. Wang, S. Lacour, S. Petrus, G. Bourdarot, J. Kammerer, N. Pourré, E. Rickman, J. Shangguan, T. Winterhalder, R. Abuter, A. Amorim, R. Asensio-Torres, M. Benisty, J. P. Berger, H. Beust, A. Boccaletti, A. Bohn, M. Bonnefoy, H. Bonnet, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, A. Chavez, E. Choquet, V. Christiaens, Y. Clénet, Et Al, Kimberly Ward-Duong

Astronomy: Faculty Publications

Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY’s astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with …

Cd-27°11535: Evidence For A Triple System In The Β Pictoris Moving Group, Andrew D. Thomas, Eric L. Nielsen, Robert J. De Rosa, Anne E. Peck, Bruce Macintosh, Jeffrey Chilcote, Paul Kalas, Jason J. Wang, Sarah Blunt, Alexandra Greenbaum, Quinn M. Konopacky, Michael J. Ireland, Peter Tuthill, Kimberly Ward-Duong, Lea A. Hirsch, Ian Czekala, Franck Marchis, Christian Marois, Max A. Millar-Blanchaer, William Roberson, Adam Smith, Hannah Gallamore, Jessica Klusmeyer

Astronomy: Faculty Publications

We present new spatially resolved astrometry and photometry of the CD -27°11535 system, a member of the β Pictoris moving group consisting of two resolved K-type stars on a ∼20 yr orbit. We fit an orbit to relative astrometry measured from NIRC2, GPI, and archival NaCo images, in addition to literature measurements. However, the total mass inferred from this orbit is significantly discrepant from that inferred from stellar evolutionary models using the luminosity of the two stars. We explore two hypotheses that could explain this discrepant mass sum: a discrepant parallax measurement from Gaia due to variability, and the presence …

A Deeper Understanding Of The R Process, Mengke Li

All Dissertations

The overarching aim of my PhD research is to deepen our understanding of r-process nu- cleosynthesis. The initial phase of my work involved developing a Machine Learning-based nuclear mass model, specifically tailored to predict nuclear masses crucial for r-process nucleosynthesis. This model was then applied to simulate the r-process, focusing on neutron-rich nuclei significant to nucleosynthesis. The simulations yielded r-process abundance patterns, extending up to thorium and uranium, that align qualitatively with the observed solar system abundance patterns, with the characteristic peaks well positioned. Advancing our study further, we introduced a novel graph-based methodology named GrRproc for calculating r-process abundances. …

An Investigation Of The Accretion Processes In T Tauri And Herbig Ae/Be Systems Using High Resolution Optical And Near-Infrared Spectroscopy, Joshua Kern

All Dissertations

Star and planet formation is intimately tied to the accretion of material from the environments in which they form. During the formation process, disks of gas and dust develop in young stellar objects through which material is facilitated to the star and forming planets. Theoretical models of these accretion processes invoke viscous spreading via hydrodynamics, as well as more complex interactions with magnetic fields be it from the stellar component or the formation environment in order to catalyze these mass flows. These accretion models predict various scenarios including magnetospheric accretion as well as supersonic accretion flows in the disk atmosphere …

Teaching Introductory Physics In The Context Of Personal And Societal Issues Of The Covid-19 Pandemic, Guang Zeng, Liang Zeng

Physics & Astronomy Faculty Publications

This paper reports on introductory physics instruction contextualized in terms of coronavirus-related personal and societal issues. Students in this descriptive qualitative study gained a strong grasp of a range of physics concepts associated with the nature and mechanisms of the spread of the coronavirus, such as projectile motion, air convection, Reynolds number, and Brownian motion; additionally, they were able to discuss the application of physics relevant to the N95 face masks. Students found this pedagogical approach engaging, as shown in their reflective writing.

Initiation Criteria For The Onset Of Geomagnetic Substorms Based On Auroral Observations And Electrojet Current Signatures, Mayowa Michael Kayode-Adeoye

Graduate Theses and Dissertations (2019 - present)

In recent years, several substorm onset criteria have been developed, either from auroral observations (many authors) or from auroral electrojet properties such as those described by (Forsyth et al., 2015; Maimaiti et al., 2019; Newell & Gjerloev, 2011; Partamies et al., 2011) The different criteria are being investigated using a low order physics model of the magnetosphere called WINDMI (Spencer et al., 2009) and inferences are being made in line with the WINDMI model. The model variables will be compared with the criteria for substorm onset proposed by examining the SML index.

The WINDMI model uses solar wind and IMF …

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 …

Godel, Escherian Staircase And Possibility Of Quantum Wormhole With Liquid Crystalline Phase Of Iced-Water - Part I: Theoretical Underpinning, Victor Christianto, T. Daniel Chandra, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

As a senior physicist colleague and our friend, Robert N. Boyd, wrote in a journal (JCFA, Vol. 1,. 2, 2022), Our universe is but one page in a large book [4]. For example, things and Beings can travel between Universes, intentionally or unintentionally. In this short remark, we revisit and offer short remark to Neil’s ideas and trying to connect them with geometrization of musical chords as presented by D. Tymoczko and others, then to Escher staircase and then to Jacob’s ladder which seems to point to possibility to interpret Jacob’s vision as described in the ancient book of Genesis …

Godel, Escherian Staircase And Possibility Of Quantum Wormhole With Liquid Crystalline Phase Of Iced-Water - Part Ii: Experiment Description, Victor Christianto, T. Daniel Chandra, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

The present article was partly inspired by G. Pollack’s book, and also Dadoloff, Saxena & Jensen (2010). As a senior physicist colleague and our friend, Robert N. Boyd, wrote in a journal (JCFA, Vol. 1, No. 2, 2022), for example, things and Beings can travel between Universes, intentionally or unintentionally [4]. In this short remark, we revisit and offer short remark to Neil Boyd’s ideas and trying to connect them with geometry of musical chords as presented by D. Tymoczko and others, then to Escherian staircase and then to Jacob’s ladder which seems to pointto possibility to interpret Jacob’s vision …

Wallaby Pre-Pilot Survey: Ultra-Diffuse Galaxies In The Eridanus Supergroup, B.-Q. For, K. Spekkens, L. Staveley-Smith, K. Bekki, A. Karunakaran, B. Catinella, Bärbel S. Koribalski, K. Lee-Waddell, Juan P. Madrid, C. Murugeshan

Physics & Astronomy Faculty Publications

We present a pilot study of the atomic neutral hydrogen gas (H I) content of ultra-diffuse galaxy (UDG) candidates. In this paper, we use the pre-pilot Eridanus field data from the Widefield ASKAP L-band Legacy All-sky Blind Survey to search for H I in UDG candidates found in the Systematically Measuring Ultra-diffuse Galaxies survey (SMUDGes). We narrow down to 78 SMUDGes UDG candidates within the maximum radial extents of the Eridanus subgroups for this study. Most SMUDGes UDGs candidates in this study have effective radii smaller than 1.5 kpc and thus fail to meet the defining size threshold. We …

Improving Inferences About Exoplanet Habitability, Risinie D. Perera, Kevin H. Knuth

Physics Faculty Scholarship

Assessing the habitability of exoplanets (planets orbiting other stars) is of great importance in deciding which planets warrant further careful study. Planets in the habitable zones of stars like our Sun are sufficiently far away from the star so that the light rays from the star can be assumed to be parallel, leading to straightforward analytic models for stellar illumination of the planet’s surface. However, for planets in the close-in habitable zones of dim red dwarf stars, such as the potentially habitable planet orbiting our nearest stellar neighbor, Proxima Centauri, the analytic illumination models based on the parallel ray approximation …

Analytic Distribution Of The Optimal Cross-Correlation Statistic For Stochastic Gravitational-Wave-Background Searches Using Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Patrick M. Meyers, Joseph D. Romano, Xavier Siemens, Anne M. Archibald

Physics & Astronomy Faculty Publications

We show via both analytical calculation and numerical simulation that the optimal cross-correlation statistic (OS) for stochastic gravitational-wave-background (GWB) searches using data from pulsar timing arrays follows a generalized chi-squared (GX2) distribution—i.e., a linear combination of chi-squared distributions with coefficients given by the eigenvalues of the quadratic form defining the statistic. This observation is particularly important for calculating the frequentist statistical significance of a possible GWB detection, which depends on the exact form of the distribution of the OS signal-to-noise ratio ρˆ ≡ Aˆ 2 gw=σ0 in the absence of GW-induced cross correlations (i.e., the null distribution). Previous discussions of …

Coastal Bathymetry Of Uae Using Satellite-Based Remote Sensing Data, Naser Salem Aldahmani

Thesis/ Dissertation Defenses

The thesis focuses on studying coastal bathymetry in the United Arab Emirates using satellite images. Developing a coastal bathymetry map in the coastal areas of the United Arab Emirates using optical satellite data and analyzing quality and accuracy. Multiple algorithms are used to draw these maps, and the project involves using the linear scale ratio to derive bathymetry in areas such as Fujairah Port and Dalma Island using Sentinel-2 images. Multiple tools in the SNAP application platform were used to perform these operations, including atmospheric correction, resampling, ground masking, sunshine removal, and dark object subtraction. Finally, the Sen2coral plugin was …

The Life Cycle Of Stars And Their Planets From The High Energy Perspective, Lia Corrales, Keivan G. Stassun, Tim Cunningham, Girish M. Duvvuri, Jeremy J. Drake, Catherine Espaillat, Adina D. Feinstein, Elena Gallo, Hans Moritz Günther, George W. King, Marina Kounkel, Carey M. Lisse, Rodolfo Montez Jr., David A. Principe, Jesús A. Toalá, Scott J. Wolk, Raven Cilley, Tansu Daylan, Margarita Karovska, Pragati Pradhan, Peter J. Wheatley, Jun Yang

Publications

One of the key research themes identified by the Astro2020 decadal survey is Worlds and Suns in Context. The Advanced X-ray Imaging Satellite (AXIS) is a proposed NASA APEX mission that will become the prime high-energy instrument for studying star-planet connections from birth to death. This work explores the major advances in this broad domain of research that will be enabled by the AXIS mission, through X-ray observations of stars in clusters spanning a broad range of ages, flaring M-dwarf stars known to host exoplanets, and young stars exhibiting accretion interactions with their protoplanetary disks. In addition, we explore the …

Employing A Fractional Basis Set To Solve Nonlinear Multidimensional Fractional Differential Equations, Md. Habibur Rahman, Muhammad I. Bhatti, Nicholas Dimakis

Physics & Astronomy Faculty Publications

Fractional-order partial differential equations have gained significant attention due to their wide range of applications in various fields. This paper employed a novel technique for solving nonlinear multidimensional fractional differential equations by means of a modified version of the Bernstein polynomials called the Bhatti-fractional polynomials basis set. The method involved approximating the desired solution and treated the resulting equation as a matrix equation. All fractional derivatives are considered in the Caputo sense. The resulting operational matrix was inverted, and the desired solution was obtained. The effectiveness of the method was demonstrated by solving two specific types of nonlinear multidimensional fractional …

Radio Emission From Low Mass Active Galactic Nuclei, Ammara Aftab

Thesis/ Dissertation Defenses

Massive black holes of a few million to billion solar masses lurk at the centers of the most present-day massive galaxies but their origin is still unknown. The low mass galaxies (M* ~ 3x10⁹ M_ʘ ) hosting black holes with masses ranging from 10³ to 10⁵ M_ʘ are ideal laboratories to test the models of black hole formation and they may help in understanding the coevolution of central black holes with their host galaxies. In this thesis, we have developed a detailed theoretical model/framework to estimate the radio emission from low mass active galactic nuclei …

Commissioning Of The Uaeu Radio Array And Pilot Low-Frequency Radio Astronomy Studies, Aisha Ali Alnaqbi

Thesis/ Dissertation Defenses

As part of the UAEU Radio Astronomy Pathway Project, a 256-element Ground-based Radio Array Facility was deployed at the UAEU. A comprehensive exploration of radio astronomy, and investigations on existing radio arrays, emphasizing low-frequency radio signals and the challenges faced at this range, are crucial for the commissioning phase of the array. A core aspect discussed is the vital role of coaxial cables in preserving the integrity of low-frequency radio signals. To address the electrical length differences between the coaxial cable pairs used to connect the array’s beamformers in the field to the beamformer controllers in the control room, precise …

Estimating Mars Surface Wind Stress And Dust Lifting Using Reanalyses Based On Emm And Other Spacecraft Observations, Haneen Edhar Abouhaligah

Thesis/ Dissertation Defenses

Dust is the primary aerosol in Mars’ atmosphere and has strong interactions with visible light from the Sun and infrared emission from the surface and air. Understanding dust dynamics in the Martian atmosphere is critical for our understanding of its weather and climate. The rate at which dust is lifted from the surface at different locations is very difficult to measure yet determines the amount of dust in the atmosphere at any given time. This thesis investigates the role of near-surface wind stress (NSWS) and dust lifting rates, using six reanalysis datasets, respectively: MACDA, EMARS, OpenMARS, ACS-TIRVIM (ExoMars observations of …