Carrie Filion

I'm a research fellow at the Center for Computational Astrophysics in the Flatiron Institute. In my work, I use both large simulations and observations of nearby stars to help us better understand how galaxies form and evolve. I am particularly interested in the formation of dynamical structures, like galactic bars, and how these structures can help us better understand both the visible (e.g. gas and stars) and invisible (dark matter) components that make up a galaxy. Lately, I've been thinking about and using 2D and 3D basis function expansions as a framework for investigating and describing galactic structure evolution. I also use 2D basis function expansions to map images of galaxies to sound, which you can learn more about in the next tab.

In addition to the above, I am also interested in Galactic chemical evolution and figuring out what the new era of spectroscopic surveys can tell us about the Milky Way and her nearest neighbors. As part of this interest, I have been actively involved in the survey planning for the ongoing Prime Focus Spectrograph (PFS) survey as a member of the Galactic Archaeology working group. PFS is mounted on the Subaru telescope and over the next few years the PFS survey will observe large numbers of faint stars in the Milky Way, M31, and nearby dwarf galaxies, enabling a variety of exciting analyses. Finally, my previous work has included explorations of the origins of Milky Way stars with surprising orbits, investigations of the stellar populations of ultra-faint dwarf galaxies, and analysis of bar-induced rearrangement of stars in stellar disks.

In my work, I use basis function expansions (BFEs) to describe and summarize key features of galaxies. A BFE uses the sum of weighted, relatively simple equations to represent a more complex distribution. When working with images, I use BFEs to represent the light profile of galaxies. In this expansion, each term represents a different physical scale (size), and the weight on each term indicates how much that term contributes to the overall brightness of the galaxy. BFEs can be thought of as a unifying language or framework for thinking about galaxies. This language quantifies the structure in galaxies and can provide a mathematical description of what galaxies look like and how they evolve.

This unifying language also lends itself to representing the galaxies through a sound via sonification, i.e. the mapping of data to sounds. By sonifying the weights on each expansion, I can communicate all of the relevant structural information about a galaxy through a single chord. Below I provide an example of one of these chords that represents the spiral galaxy M101. I am pioneering this new technique, and as part of this endeavor I am working to quantify the efficacy of classifying galaxies using audio samples like the one I share here.

Galaxy Image: ESA/NASA

Project Investigators for the original Hubble data: K.D. Kuntz (GSFC), F. Bresolin (University of Hawaii), J. Trauger (JPL), J. Mould (NOAO), and Y.-H. Chu (University of Illinois, Urbana) Image processing: Davide De Martin (ESA/Hubble) CFHT image: Canada-France-Hawaii Telescope/J.-C. Cuillandre/Coelum NOAO image: George Jacoby, Bruce Bohannan, Mark Hanna/NOAO/AURA/NSF)

cfilion@flatironinstitute.org