Debris Disk Stars are stars that are surrounded by dust and diffuse gas. Certain elements in the gas and dust absorb the light from the star and show up as an absorption-line spectrum. Our goal was to find trends in the elemental abundance patterns of similar debris disk stars. We took 30 debris disk stars that are similar in mass and surface temperature and measured their elemental abundances. Using Spectroscopy through IRAF’s s-plot tool we found accurate abundances of certain elements. We found abundances of metals including Iron, Nickel, Sodium, Carbon, and Oxygen. Comparing their Metallicities ([x/Fe]) we can find certain trends between the abundance of the elements and their condensation temperatures. From the 30 stars in the data-set, we chose 3 of the most interesting objects. The first star we chose, HD162826, is the closest in terms of motion and chemical abundances to the Sun. The second star, HD187691, has a small debris disk. The third star, HD122652, has a large debris disk. For HD162826, we found the metallicity of the refractory elements (high condensation temperature, >1200 K) to be spread around the 0 metallicity marker ([x/Fe]=0), for HD187691 we found most of the refractory elements above [x/Fe]=0 with the rest being very close to zero, and for HD122652 we found that the metallicities of most of the refractory elements were negative. The trends we found are small and could be explained by observational uncertainty, therefore further analysis of our data set would be required to make stronger conclusions. By accurately measuring more absorption lines from our dataset, possibly more connections can be made about the properties of Debris Disk Stars.

Nitrogen-vacancy centers (NVs) are defects in diamond whose spin and optical properties enable their use as qubits, the basic building blocks of quantum information processing (QIP). Our group is interested in forming NV centers with good optical properties near the surface of a diamond substrate to create a scalable QIP platform. To form these near-surface NV centers, we implant nitrogen ions into a diamond and subsequently anneal. Recent published literature suggests NV centers formed by implantation and annealing protocols have poor optical properties, including optical linewidth and spectral diffusion, while NV centers formed from naturally-grown-in nitrogen have good optical properties. In this project, we examine this discrepancy by studying the optical properties of NVs formed from implanted nitrogen (¹⁵N isotope) versus grown-in nitrogen (¹⁴N isotope). We implant diamonds with ¹⁵N ions, anneal to form NV centers, then identify each NV center’s nitrogen isotope using optically-detected magnetic resonance (ODMR) to establish the NV’s origin (from implanted or naturally occurring nitrogen.) We then measure the optical properties of the NV centers using photoluminescence excitation (PLE). Preliminary results show a statistical correlation between good optical properties and ¹⁴N NV centers. In this project, I aim to analyze PLE data to measure NV optical properties, use ODMR to identify NV isotopes, and correlate these two measurements for the same NV centers. This work will identify the source and study the spectral properties of implanted NV centers in diamond, ultimately assisting in the development of a scalable QIP platform.

This research explores two different projects. Firstly, systematic measurements of the resistivity, susceptibility, and quantum oscillations are presented for single-crystal samples of the chemically substituted RAgSb₂ (R=Gd,La). Doping the parent compound LaAgSb₂ with Gd explores the effect of magnetic doping and applying chemical pressure to the crystal. La_1−xGd_xAgSb₂ exhibits charge density ordering around that is suppressed with increase Gd percentages, while Gd_1−xY_xAgSb₂ exhibits anti-ferromagnetic ordering that is suppressed with increasing Y percentages. Resistivity and susceptibility data are used to identify phase transition temperatures and create a temperature vs doping phase diagram for each chemical substitution family. Magnetic quantum oscillation data is presented suggesting changes in the Fermi surface and effective mass with chemical doping. Secondly, the chiral magnetic effect is the generation of electric current induced by an external magnetic field, resulting in a chiral imbalance. This imbalance creates a strong current by pushing oppositely charged particles in opposite directions within the material. The first observation of the chiral magnetic effect was reported through the measurement of magneto-transport in ZrTe₅, specifically a large negative magnetoresistance when magnetic field and current are parallel. In materials with a large field-induced anisotropic resistivity tensor, such as ZrTe₅, an effect called “current jetting” can lead to a strong apparent negative longitudinal magnetoresistance. Finite element analysis models, contrusted with COMSOL Multiphysics software, of the potential distribution inside ZrTe₅ have been created to investigate possible underlying effects of current jetting.

 Mid galaxy merger, a process called dynamical friction allows collided galaxies’ central massive black holes (MBHs) to spiral into the center of the system. Dynamical friction (DF) is a result of interactions between background material of small masses and one larger mass, such as a MBH. This creates a wake of particles behind the MBH, causing a gravitational pull opposite to its velocity, slowing it down. This process controls the orbit of non-central black holes in a galaxy and drives the creation of massive black hole binaries, prospective gravitational wave sources for current and future low-frequency detectors. The standard equation used to estimate DF, the Chandrasekhar DF formula, assumes that a galaxy has a uniform density profile, and all small particles have the same mass with Maxwellian velocity distribution. With this formula, many scenarios such as density fluctuations, large mass interactions, and perpendicular force are ignored. These conditions are not representative of realistic galactic environments and thus provide an incomplete look at dynamical friction. Taking a Monte-Carlo approach, we developed a numerical formula, to create an accurate and computationally efficient method to calculate the dynamical friction. Our method allows for density fluctuations and a range of particle masses and velocities to be accounted for.

The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will conduct an all-sky survey and uses difference imaging to identify and classify variable sources. Galaxies with an actively accreting supermassive black hole at the center, or active galactic nuclei (AGN), can vary in brightness significantly. They are powerful tools for improving our understanding of high energy astrophysics. We present an analysis of a subset of high-probability AGN from the High Cadence Transient Survey (HiTS) data release, a precursor for LSST. By comparing difference imaging light curves generated by both HiTS and LSST software, we eliminate bad sources, crossmatch with other datasets, and identify previously unknown AGN. We use these comparisons to assess why some known AGN were not found in the HiTS data. We also make suggestions for how the LSST software can be used to maximize variable AGN science.