Research

I've worked on the phase space spirals with Prof. Kathryn Johnston since I arrived at Columbia in 2022. These spirals were discovered by Antoja et al. (2018) using Gaia DR2 data in 2018, when they found a spiral structure in the z-v_z plane for Solar Neighborhood stars, suggesting a past perturbation. Since then, researchers have discovered that these spirals exist all across the Galactic disk and are prevalent not just in density but also in velocity and even chemistry. But much remains unknown about the phase spirals, including their cause and how they evolve over time.

In my work, I have been using basis function expansions (BFEs) and Singular Spectrum Analysis (SSA) on simulations to understand correlations and trends in phase spiral properties across large scales of galactic disks. In Tavangar et al. (2026) we found that phase spirals wind up differently in different parts of the disk, with inner disk phase spirals experiencing large delays in winding compared to the outer disk. This has significant implications for how we should interpret observations, suggesting that perturbation times derived from outer disk phase spirals are likely to be closer to the true perturbation times. It also points to the importance of understanding how self-gravity affects phase spiral evolution, which we start to explore in our paper but is still an open question. In an upcoming paper, I will explore the correlations between phase spiral amplitudes across galactic disks. These correlations give us a new way to explore the nature of the perturbation that cuased the phase spirals.

In the next few years I am excited to use the tools we have developed to explore phase spiral dynamics in more detail, as we attempt to connect the simulations with the observations and learn more about the history of the Milky Way. There may even be a connection to small scale dark matter halos which I am thinking about exploring in the next year.

In 2025, Dr. Adrian Price-Whelan and I collaborated to create a framework to model the density of stellar streams, which we applied to GD-1 as a test. The framework builds on previous similar work but has the novelty of including a method to model stars away from the main stream track. These stars, such as the "spur" in GD-1, are likely to be the most constraining when trying to understand the effects of small dark matter subhalos on streams.

I am excited to extend this framework to many more streams. The idea is to create a catalog of density models along with the most interesting or constraining stream mfeatures which can be used by the community as follow-up target regions as we attempt to constrain dark matter with stellar streams. With many new surveys and telescopes coming online in the next few years, we are going to have a wealth of new data on streams, and I hope this framework can help us make the most of it!