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Jeffery Jorges

Undergraduate Major: Physics, Astronomy Specialization

Future Plans: Ph.D. in Astrophysics

Jeffery Jorges

Jeffery Jorges was born and raised in South Florida. He is pursuing a Bachelor’s degree in Physics, specializing in Astronomy. He serves as the current president of UCF’s Astronomy Society and vice-president of UCF’s chapter of the Society of Physics students working to help share his love of science with others by participating in science outreach for his university and general public. Since January 2015 he has also worked as a research assistant at UCF’s Center Of Microgravity Research studying low-velocity collisional systems to better understand the evolution of planetary ring systems and the formation of planetesimals. His academic interest is in using computational methods in astrophysics to study dark matter as well as the formation and evolution of galaxies. Jeffery aspires to obtain his Ph.D. in Astrophysics and become faculty at a university doing research on dark matter and galaxies.

Scaling the Peaks: Cataloging Halos from Cosmological N-Body Simulations

Conducted at the University of California, Santa Cruz

Mentors: : Dr. Brant Robertson, Department of Astronomy & Astrophysics, University of California, Santa Cruz

Abstract: Dark matter comprises most of the mass of structures in the universe, and forms gravitationally-bound dark matter halos that host galaxies. Although we are unable to study dark matter structures through direct observations, we can use cosmological N-body simulations to model theoretically the formation of dark matter halos and learn about their properties. This modeling requires the rapid and reliable identification of dark matter halos in the simulation data through specially-designed “halo finder” algorithms. Current algorithms developed to analyze these types of simulations are limited by the size of the simulation, causing them to become more inefficient as the size of the simulation grows. We present a new halo finder code ScalePeaks designed to process large cosmological simulations quickly and efficiently, identify dark matter halos, and measure their properties. Our code processes the simulation data in a massively parallel way, allowing us to leverage new computer architectures for increase computational efficiency. We describe the physical algorithm of our method and show how to perform end-to-end analysis of cosmological simulations including generating initial conditions, evolving the system from early times to the present day, and identifying and characterizing the resulting population of dark matter halos. ScalePeaks allows us to better understand our universe by being able to now study it thought these simulations with an increased speed, at larger sizes, and in more detail to be able learn more about the large scale structure of our universe.

From pebbles to dust: Experimental observation of low-velocity collisional systems

Conducted at the University of Central Florida

Mentors: : Dr. Adrienne Dove, Department of Physics, University of Central Florida

Abstract: Particle size evolution in planetary ring systems can be driven by collisions at relatively low velocities (<1 m/s) occurring between objects with a range of sizes from very fine dust to decimeter-sized objects. In these complex systems, collisions between centimeter-sized objects may result in particle growth by accretion, rebounding, or erosive processes that result in the production of additional smaller particles. The outcomes of these collisions are dependent on factors such as collisional energy, particle size, and particle morphology. Numerical simulations are limited by a need to understand these collisional parameters over a range of conditions. We present the results of a sequence of laboratory experiments designed to explore collisions over a range of these parameters. We are able to observe low-velocity collisions by conducting experiments in vacuum chambers in our 0.8-sec drop tower apparatus. Initial experiments utilize a variety of impacting spheres, including glass, Teflon, aluminum, stainless steel, and brass. These spheres are either used in their natural state or are “mantled” - coated with a few-mm thick layer of a cohesive powder. A high-speed, high-resolution video camera is used to record the motion of the colliding bodies. These videos are then processed and we track the particles to determine impactor speeds before and after collision and the collisional outcome; in the case of the mantled impactors, we can assess how much of the powder was released in the collision. We also determine how the coefficient of restitution varies as a function of material type, morphology, and impact velocity. Impact velocities range from about 20-60 cm/s, and we observe that mantling of particles significantly reduces their coefficients of restitution. These results will contribute to an empirical model of collisional outcomes that can help refine our understanding of dusty ring system collisional evolution.