Astrophysics and Astronomy Commons^™

Unraveling The Physics Of Quasar Jets Using Hst Polarimetry, Devon Clautice

Theses and Dissertations

We present a multiwavelength study of three high-power FR II (quasar) jets -- 3C 273, PKS 0637-752, and 1150+497 -- with an emphasis on new high-quality Hubble Space Telescope (HST) optical polarimetry and Chandra X-ray Observatory imaging. Relativistic jets from active galactic nuclei transport energy and mass from the supermassive black hole’s accretion region out to Megaparsec-scale lobes, with effects that feedback into galaxy formation and cluster energetics. We build on recent work which has called into question our fundamental understanding of FR II jet physics, and suggest that highly-efficient particle acceleration must be taking place in situ …

Remnant Polarization And Structural Arrangement In P(Vdf-Trfe) Electrospun Fiber Meshes Affect Osteogenic Differentiation Of Human Mesenchymal Stromal Cells, Bahareh Azimi, Massimiliano Labardi, Mohammad Sajad Sorayani Bafqi, Teresa Macchi, Claudio Ricci, Veronica Carnicelli, Lorenzo Scarpelli, Istiak Hussain, Francesca Matino, Mohammed Uddin

Physics & Astronomy Faculty Publications

Highlights

• The type of solvent had noticeable effects on morphology and piezoelectric properties of P(VDF-TrFE) electrospun fibers.

• Using MEK as a solvent and specific environmental conditions led to the obtainment of surface nanopores.

• Uniaxially aligned fibers exhibited higher β phase and mechanical properties than random ones.

• Randomly oriented fibers had higher remnant piezoelectric properties (Vout, d31 piezoelectric coefficient) than aligned ones.

• Human mesenchymal stem cells cultured on randomly oriented fibers showed an accelerated osteogenic differentiation.

Abstract

Many tissues and cells are influenced by mechano-electric stimulation, thus the application of piezoelectric materials has recently received considerable attention in tissue engineering. …

Local Map Of The Interstellar Fuv Field, David Lomeli

Open Access Theses & Dissertations

The strength of the far-ultraviolet field is an important parameter in determining the chemistry that takes place in star-forming regions. FUV radiation is produced by bright stars in the galaxy and absorbed by interstellar dust. By using newly available maps of the dust distribution, in conjunction with catalogs of stellar positions and spectra, we created a local map of the FUV field ranging from 6-13.6 eV. We find a value of 6.57*10^-14 erg/cm^3 at the location of the Sun. This value, alongside its spectra, follow previous measurements and estimates of the FUV field at the Sun. We further study the …

Modeling The Spatiotemporal Variations Of The Magnetic Field In Active Regions On The Sun Using Deep Neural Networks, Godwill Asare Mensah Mensah

Open Access Theses & Dissertations

Solar active regions are areas on the Sun's surface that have especially strong magnetic fields. Active regions are usually linked to a number of phenomena that can have serious detrimental consequences on technology and, in turn, human life. Examples of these phenomena include solar flares and coronal mass ejections, or CMEs. The precise predictionof solar flares and coronal mass ejections is still an open problem since the fundamental processes underpinning the formation and development of active regions are still not well understood. One key area of research at the intersection of solar physics and artificial intelligence is deriving insights from …

Mapping Star Formation Histories In Nearby Galaxies To Source Lyman Continuum Photon Escape, Katie Kudla '24

Engineering & Physics Student Scholarship

Katie Kudla ’24, Physics major
Faculty Mentor: Dr. Joseph Ribaudo, Engineering and Physics

Investigation Of Surface Chemistry From Electron Irradiation Of Synthetic Schreibersite, Tyler Davis

Master's Theses

While phosphorus is one of the key elements for life on Earth, it has relatively low abundance in extraterrestrial environments, making it a target for astronomers and astrobiologists interested in the possibility of life beyond our planet. Schreibersite (Fe,Ni)₃P is one of the first P-containing minerals to condense during planetary cooling and one of the primary P-containing minerals in iron and stony-iron meteorites. Therefore, it is a likely P-bearing mineral in cometary cores and dust grains within the interstellar medium and circumstellar envelopes. Experiments in this project were performed with the aim of observing the formation of small …

Models Of Low Mass Stars As Physical Labratories, Emily M. Boudreaux

Dartmouth College Ph.D Dissertations

Low mass stars account for approximately 70 percent of the stellar populations (Conroy & Van Dokkum, 2012); yet, due to their small sizes and cool temperatures they account for only a small fraction of the galaxies luminosity function (Laughlin et al., 1997). Moreover, due to the lack of laboratory conditions available to astronomy and astrophysics low mass stars can provide a rare controlled environment for calibrations of numerical models. Consequently, across multiple domains there has been significant interest in these key astronomical objects. In this thesis I present three projects which have further revealed properties of low mass stars and …

Significance And Reflection Of Lunar Exploration, Jiaqi Liu

Bulletin of Chinese Academy of Sciences (Chinese Version)

Although China's lunar exploration project started later than the Soviet Union and the United States, it is the first country to land probes and retrieve samples on both the right side and the reverse side of the Moon. There have been many major breakthroughs in space technology, and many important achievements in scientific research as well. It has extended the life of the Moon for about 1 billion years.

A Distinct Radial Acceleration Relation Across The Brightest Cluster Galaxies And Galaxy Clusters, Pengfei Li, Stacy S. Mcgaugh

Faculty Scholarship

Recent studies reveal a radial acceleration relation (RAR) in galaxies, which illustrates a tight empirical correlation connecting the observational acceleration and the baryonic acceleration with a characteristic acceleration scale. However, a distinct RAR has been revealed on brightest cluster galaxy (BCG) cluster scales with a seventeen-times-larger acceleration scale due to the gravitational lensing effect. In this work, we systematically explore the acceleration and mass correlations between dynamical and baryonic components in 50 BCGs. To investigate the dynamical RAR in BCGs, we derived their dynamical accelerations from the stellar kinematics using the Jeans equation through Abel inversion and adopted the baryonic …

Modeling An Extra Planet's Effects On Earth, Emily Simpson

Aerospace, Physics, and Space Science Student Publications

Orbital dynamics play a crucial role in determining the habitability of exoplanets, and many models have been developed to study the dynamical evolution of broader planetary system structure. To further investigate the implications this has regarding planetary habitability, this project simulated the evolution of the Solar System with an additional planet orbiting in place of the Asteroid Belt using the Gravitational Rigid-body InTegrator (GRIT) package. 21 total simulations were run for 100,000 years with varying values for the extra planet’s mass (from 0.01 to 10 Earth masses) and orbital parameters (based on the 4 most massive asteroids in the Asteroid …

A New Effective Gravitational Lensing Approach To Constrain Dark Matter, Birendra Dhanasingham

Physics & Astronomy ETDs

Galaxy-scale strong gravitational lenses offer a unique window into understanding the nature and distribution of dark matter at sub-galactic scales. Beyond the main-lens subhalos, the inclusion of line-of-sight dark matter halos has become essential in lens studies due to their substantial role in perturbing lensed images, making multi-plane lensing a crucial aspect of any lens study. We highlight that these line-of-sight halos appear extended tangentially along the lensing critical line in the effective convergence maps due to the nonlinear nature of multiplane lensing, resulting in a characteristic anisotropic signature in the deflection field. Leveraging tools from large-scale structure analyses, this …

Mapping Out The Sky, Erik Johnson

Natural Science Faculty

Astronomers are often asked to help identify UFOs. It's a reasonable request since the term means "unidentified flying object." An untrained observer may not know which celestial objects are visible at night, even in light-polluted skies. They may mistake a plane for a planet, a bright star, or a satellite.

Quantum Computation Using Large Spin Qudits, Sivaprasad Thattupurackal Omanakuttan

Physics & Astronomy ETDs

This dissertation explores quantum computation using qudits encoded into large spins, emphasizing the concept of quantum co-design to harness the unique capabilities of physical platforms for enhanced quantum information processing. First, we delve into the generation of high-fidelity universal gate sets for quantum computation with qudits. Leveraging principles from quantum optimal control, Rydberg physics, and the atomic structure of alkaline-earth atoms, we propose protocols for high-fidelity universal gate sets in the ground state of ⁸⁷Sr with reasonable experimental parameters. Next, we analyze schemes to encode a qubit in the large spin qudits for fault-tolerant quantum computation (FTQC). By comprehending …

Simulating Continuous Gravitational Waves, Ivan Mihael Villalba Moran

SACAD: Scholarly Activities

Using a table-top Michelson Interferometer to replicate Laser Interferometer Gravitational-Wave Observatory (LIGO) arrangement, we use sound waves to simulate Continuous Gravitational Waves (CWs). Using the NumPy package in Python programming, we recover the frequency of the injected sinusoidal signal using the mathematics of the Fourier Transform. Currently, we are trying to implement the Hidden Markov Model along with the Viterbi Algorithm as a method to detect Wandering Continuous Gravitational Waves.

The Jesuit Tradition Of Astronomy At Holy Cross, Sarah Campbell M.A., M.S.I.S.

Staff publications

This paper summarizes the study of astronomy and related fields as part of the curriculum at the College of the Holy Cross. It briefly profiles four Jesuit priests who were associated with Holy Cross and made significant contributions to the study of astronomy, solar physics and other scientific disciplines. The history of a campus observatory is briefly described as well.

This paper was presented an event sponsored by the Holy Cross Libraries to commemmorate the solar exclipse which occurred April 8. 2024.

A Search For Intermediate-Mass Black Holes In Compact Stellar Systems Through Optical Emissions From Tidal Disruption Events, Richard T. Pomeroy, Mark A. Norris

Physics & Astronomy Faculty Publications

Intermediate-mass black holes (IMBH) are expected to exist in globular clusters (GCs) and compact stellar systems (CSS) in general, but none have been conclusively detected. Tidal disruption events (TDEs), where a star is tidally disrupted by the gravitational field of a black hole, have been observed to occur around the supermassive black holes (SMBH) found at the centres of galaxies, and should also arise around IMBHs, especially in the dense stellar cores of CSS's. However, to date none have been observed in such environments. Using data from the Zwicky Transient Facility (ZTF) we search for TDEs associated with CSS, but …

Search For Extreme Mass Ratio Inspirals Using Particle Swarm Optimization And Reduced Dimensionality Likelihoods, Xiao-Bo Zou, Soumya Mohanty, Hong-Gang Luo, Yu-Xiao Liu

Physics & Astronomy Faculty Publications

Extreme-mass-ratio inspirals (EMRIs) are significant observational targets for spaceborne gravitational wave detectors, namely, LISA, Taiji, and Tianqin, which involve the inspiral of stellar-mass compact objects into massive black holes (MBHs) with a mass range of approximately 104 ∼107��⊙ . EMRIs are estimated to produce long-lived gravitational wave signals with more than 105 cycles before plunge, making them an ideal laboratory for exploring the strong-gravity properties of the spacetimes around the MBHs, stellar dynamics in galactic nuclei, and properties of the MBHs itself. However, the complexity of the waveform model, which involves the superposition of multiple harmonics, as well as the …

Radial Acceleration Relation Of Galaxies With Joint Kinematic And Weak-Lensing Data, Tobias Mistele, Stacy S. Mcgaugh

Faculty Scholarship

We combine kinematic and gravitational lensing data to construct the Radial Acceleration Relation (RAR) of galaxies over a large dynamic range. We improve on previous weak-lensing studies in two ways. First, we compute stellar masses using the same stellar population model as for the kinematic data. Second, we introduce a new method for converting excess surface density profiles to radial accelerations. This method is based on a new deprojection formula which is exact, computationally efficient, and gives smaller systematic uncertainties than previous methods. We find that the RAR inferred from weak-lensing data smoothly continues that inferred from kinematic data by …

Phys 211h

Department of Physics and Astronomy: Syllabi

No abstract provided.

Phys 918

Department of Physics and Astronomy: Syllabi

No abstract provided.