Micah Oeur

My project leverages cosmological zoom-in simulations to study the structure and content of Milky Way–like galaxies using a novel technique that combines stellar kinematics and chemistry to recover the Galactic mass distribution and probe dark matter.

Orbital Torus Imaging (OTI) is a method for determining the Milky Way’s gravitational potential, which guides the orbits of stars, gas, and dark matter, using stellar data from large surveys. OTI uses gradients in stellar astrophysical quantities, like the amount of chemical elements in a star, as functions of dynamical quantities, like energy, to estimate the Galactic mass distribution. I validated OTI in a Feedback in Realistic Environments (FIRE-2) cosmological hydrodynamic simulation, called m12i. This enabled a comparative analysis between known FIRE-2 potential parameters, like the vertical acceleration or the total surface mass density, to the analogous quantities recovered by OTI. I quantified OTI’s accuracy within 16 different regions in the simulated galactic disk and found that OTI recovers the known vertical acceleration profiles within 3σ/1σ errors for 94%/75% of regions. OTI is sensitive to the local, instantaneous structure of the disk, losing accuracy for regions with large (>1.5 kpc) scale heights and low total density at a height of 1.1 kpc.