In this study, we explore the potential of using data from the DECam Deep Drilling program for asteroid science. The program, originally intended for supernovae and variable star science, produces valuable data that can be used to discover and analyze asteroids. Our focus is on the COSMOS fields, which are observed 5 times in each of the g, r, and i filters every 3 nights. We employ Heliolinc to match the data with known asteroids and discover 296 independent rediscoveries of known asteroids, as well as new discoveries that require further analysis. To analyze the known asteroids, we use forced photometry based on JPL ephemerides to measure their colors. Our results show that the average (g-r) color gets bluer and (r-i) gets redder with increasing distance from the sun. We use this information to develop a distance color metric that combines the colors to maximize sensitivity to distance. Additionally, for some of the best measured objects, we determine their rotation periods using Lomb-Scargle analysis. Our preliminary results demonstrate the potential of the DECam Deep Drilling program for asteroid science, particularly in analyzing asteroid colors and rotation periods.

The widely accepted theory for how Earth’s moon formed begins with an impact to Earth by a Mars sized protoplanet. This impact creates a disk of debris around the Earth, and the moon is subsequently formed as the debris collides and coalesces. Previous studies have modeled the debris disk in a hydrodynamic environment, but results have found that moon formation is uncommon. This research project models the debris disk after it has cooled and condensed into a collection of solid particles using an N-Body simulation. These simulations are run using the ChaNGa code developed by the University of Washington’s N-Body shop and processed on the Hyak supercomputer. Simulations begin with an initial conditions file that we generate with different parameters, including particle resolution, angular momentum, and coefficient of restitution. From each initial conditions file the simulation runs time-progressions that model each particles position and velocity at every time-step, calculating the collective gravitational forces between all of the particles and recording any collisions that occurred. I analyze the data using plots detailing the eccentricity, mass, and semi-major axis of objects that form. Previous results from work I have completed on this project appear to show robust moon formation, with roughly lunar sized objects forming around the Roche limit. Future work on this project will include running more simulations with similar initial conditions to determine how common moon formation is, as well as analyzing the data using plots of semi-major axis vs. number of collisions/bodies accreted to determine if there are specific regions of the debris disk where the moons’ mass is originating from. While previous studies have found that a moon is only formed at very specific impact angles and sizes, this study looks to see if the moon formation mechanism may be more robust when modeled using N-Body simulations.

 The Circumgalactic Medium (CGM) refers to the vast outer regions of gas within the gravitation influence of a host galaxy. The CGM contains a significant amount of gas flowing into and out of the host galaxy; transitions such as HI and OVI are frequently observed in absorption along quasar sightlines that pierce the CGM within close projected impact parameters. Absorption feature properties such as column density and central wavelength can provide insight into the content and kinematics of the CGM. Our research team, known as the Werk SQuAD (Student Quasar Absorption Diagnosticians), is currently assessing the two-dimensional distribution of gas in the CGM around galaxies with a redshift value of less than 0.65. We use measured gas column densities from the Hubble Space Telescope’s Cosmic Origins Spectrograph quasar absorption spectra and a program called GALFIT to measure galaxy inclination and azimuthal angles, to help us understand these kinematics relative to their orientation to the background quasar. All host galaxies have redshifts measured spectroscopically by the Werk SQuAD as part of the CGM2 survey. In particular, the galaxy inclination angle, combined with the quasar azimuthal angle and absorption-line column densities provide a measure of the extent to which gas flows concentrate along the major or minor axes of galaxies (along the disk of the galaxy or flowing near or away from the galactic center). Here, we examine trends in the CGM with quasar azimuthal angles and ion column densities. Ultimately, our goal is to further understand the physical interdependence of the gas that flows through the CGM and galaxy evolution.

Massive stars place powerful constraints on stellar evolution and are observed in a menagerie of exotic evolutionary phases. These objects play a crucial role in regulating their environments. They drive the chemical evolution of their host galaxies, and set the energy balance of their surroundings via feedback processes. Due to the importance of massive stars, placing constraints on their evolution serves as a key to understanding galactic ecosystems. Notably, stellar variability is a powerful probe of the poorly-constrained physics of massive star evolution. In particular, variability studies on ensembles of evolved massive stars can significantly constrain stellar evolution. We aim to understand the variability of hot massive stars through a census of these objects. We accomplish this using data from the Gaia mission, cross-matched with light curves from the Zwicky Transient Facility (ZTF). We expect to characterize the evolution of massive star variability timescales and amplitudes along the main sequence and beyond. Our results will place key constraints on the evolution of massive stars. 

Binary systems containing a compact object may exhibit periodic brightening episodes due to gravitational lensing of the lower-mass companion as it transits the compact object. Such self-lensing systems have been discovered before by identifying this periodic brightening in light curves. We explore the possibility of using this method to detect new compact objects with data from the Zwicky Transient Facility (ZTF). Thanks to its extensive optical variability coverage of the Northern Hemisphere sky, ZTF provides an ideal dataset for this search. We present methods used in a systematic search for self-lensing signatures in Galactic binaries, and final candidates that may exhibit these signatures. This method could become a new means of discovering noninteracting compact binaries and provide a way to estimate their masses.

Much of cosmology, including the age, shape, and evolution of the universe, depends upon the values of certain parameters. The Hubble Constant is one such parameter and is currently undergoing thorough investigation: our two primary means of measuring it yield two conflicting values. Is this merely a series of errors, or is there new physics to be uncovered? In order to eliminate measurement error as an explanation, we need to reduce uncertainty, but our current methods of measuring the movement of distant galaxies are unlikely to yield the necessary precision. Instead, we are developing a new method that may be able bypass the current reliance on a series of calibrations. Fast Radial Bursts are sufficiently point-like to detect the curvature in their wavefronts; hence the time delay registered between several satellites a sufficient distance apart can be used to determine the curvature of the pulse and hence the distance to the burst. More precise measurements of the distance to Fast Radio Bursts will lead to a better measurement of the Hubble Constant and the evolution of the dark energy. Further, using radio telescopes will require minimal advancement in precision measurement given already active GPS methods. While exploring what configuration will yield the greateat sensitivity, I have found a particular equidistant configuration of satellites that is able to maintain a consistent range of error regardless of what direction the FRB signal is coming from. Currently I am extending this search to additional satellites and numerous FRB sources to show that our model is able to achieve sub-1% precision in the Hubble Constant. If so, our model could be used to resolve the Hubble Tension, or to show that new physics such as new behaviors in dark energy is in fact present. 

The Circumgalactic Medium (CGM) is an extended structure surrounding galaxies, populated with hot diffuse gas and cold dense clouds of gas. The CGM acts as an intermediary between gas within galaxies (Interstellar Medium, or ISM) and gas between galaxies (Intergalactic Medium, or IGM). Insights into its properties and behavior could lead to a connection between the CGM and galaxy evolution, and the transition of a galaxy from star-forming to non-star-forming (quiescent). One standard method of observing the CGM is by measuring the absorption of light by elements in the CGM along its path to Earth, and since elements ionized to different degrees have distinct absorption signatures that can be observed, we can use them to determine the properties of the cool CGM. Our project aims to determine how the radiation from two sources of radiation—the central galaxy and the background—affect the ionization of this gas. Using observational data from the Hubble Space Telescope, we aim to constrain the dominant ionization mechanism of the cool CGM by comparing the data to physically-motivated fits and theoretical models developed by Dr. Faerman and Prof. McQuinn. Preliminary results show that by relating the density of CGM gas to the star-formation rate in the galaxy, the model is more consistent with the data, suggesting a relationship between the two properties. We are currently testing our method with one specific, well-modeled galaxy sample, and our framework allows including other existing samples as well as new, future observations. Modeling the properties of the CGM and how it interacts with galaxies will help us understand how galaxies form and evolve over cosmic times; one of the great open questions in modern astrophysics.