Constraining Dark Matter Models Using Isolated Elliptical Galaxies
Physical and Biological Sciences
Physics
Dark matter accounts for roughly a quarter of the mass in the universe and affects structure predominantly on large scales. Yet little is known about the precise nature of the dark matter particle aside from the certain properties that it interacts gravitationally and does not interact electromagnetically. We wish to understand the interaction mechanism of dark matter. The geometric test uses the shape (quantified by ellipticity) of a dark matter halo to conclude whether dark matter is self-interacting or collisionless (termed cold dark matter). Previous studies found evidence for a cold dark matter halo in NGC 720 using a geometric argument. However, NGC 720 is a single galaxy and is perhaps an outlier. Thus, we are motivated to study a number of galaxies via the geometric test. I identify candidate galaxies (isolated ellipticals in approximate hydrostatic equilibrium) and present analytic forms of the galactic components relevant to our study: density, potential, and mass for the total matter, dark matter, stellar material, and gas. Using a sample of galaxies, we hope to classify the elusive dark matter particle.
