N-body Solvers & Star Clusters

There are a variety of ways to simulate self-gravitating systems, and globular clusters push the boundaries of what can be done computationally. Brute-force, O(N²) approaches take many months to complete on a supercomputer due to the dramatically varying spatiotemporal scales present in the resolution of the underlying dynamics.

I led the development of KRIOS (first code paper here), a new basis-expansion N-body code specifically designed for modeling globular clusters where the spherical symmetry might be broken (e.g., rotation or tides). KRIOS can act as an intermediary between direct N-body and particle-spray codes for the modeling of stellar streams as well; the paper detailing our findings has been submitted to ApJ and a preprint is available on the arXiv.

Galactic Archaeology

Galactic archaeology is the branch of research devoted to determining the formation history of the Milky Way. Galaxies form in what is known as a hierarchical process; smaller galaxies are accreted by larger galaxies, which in turn causes the larger one to grow. As the smaller galaxy is tidally stripped, it leaves behind signatures in the form of objects like stellar streams and globular clusters.

As a summer intern at MIT Lincoln Lab, I developed a routine for identifying substructure in the Milky Way comprised of RR Lyrae variables, a popular standard candle in this context, based on hierarchical clustering. You can learn more about our results in Cook et al. (2022). I have been expanding on this effort with the new Gaia DR3 release with an eye towards a more general identification routine for forthcoming surveys.

Near-field Cosmology

It is theorized that during a period of rapid inflation after the Big Bang, small quantum fluctuations were forced onto macroscopic scales. Cosmologists can use observations of the cosmic microwave background to map these overdense anisotropies in the Universe, in addition to determining the abundances of things like baryonic matter and dark energy. With this set of initial conditions, a wide set of cosmological simulations have been developed.

These simulation suites are comprised of state-of-the-art algorithms that treat astrophysical phenomena operating on different length and time scales simultaneously. The outputs can then be analyzed to test the effects of underlying physics theories (e.g., AGN feedback, small-scale DM distribution) on observables.

During my first year in Leiden, I analyzed low-mass, star-forming galaxies produced by the EAGLE simulations. My first project presents an analysis of the circumgalactic medium (CGM) of these galaxies; often defined as the material gravitationally bound to the galaxy but outside of the disk, the CGM is critical to understanding galaxy formation and evolution.