Research
My research focuses on understanding the physical conditions of molecular gas in a variety of environments, and how those conditions influence star formation. I am particularly interested in the star formation and gas conditions of interacting or starburst galaxies, where massive star clusters called super star clusters (SSCs) are formed. We know that the formation of such massive clusters was important in the early universe, as demonstrated by the ubiquitous presence of ancient globular clusters in massive galaxies. Studying extreme environments in the local universe where SSCs are able to form can give us insights into what the gas conditions of the early universe may have been like.
Much of my research has also focused on the Magellanic Clouds, which can tell us about both dwarf galaxy interactions and low-metallicity environments. Both of these aspects are essential for understanding the early univerese and galaxy evolution. The interaction of the LMC and SMC likely contributed to the formation of the largest star cluster in the Local Group, R136 in the 30 Doradus region in the LMC. The proximity of these galaxies make them an excellent place to study in detail how this interaction affects the molecular gas conditions and star formation.
You can find a list of my publications on ADS here.
My PhD thesis is available here.
A video of my PhD defense is available here.
The Firecracker: A Proto-SSC in the Antennae Galaxies
The Antennae galaxies is a pair of merging galaxies that has formed thousands of SSCs. I characterize the Firecracker molecular cloud, which has the necessary size and mass to form an SSC, but has not yet formed any stars. This is the only pre-SSC cloud identified at such an early stage of evolution thus far. I find that the Firecracker requires an extremely high external pressure to remain gravitationally bound. The weight of surrounding material is not sufficient to provide this pressure, but I find evidence for cloud-cloud collision, which could provide the needed ram pressure to keep the cloud bound.
Paper: https://ui.adsabs.harvard.edu/abs/2019ApJ...874..120F/abstract
Fitting RADEX Models to Map Physical Conditions
I developed a new multi-line non-LTE fitting tool based on models from RADEX to produce maps of the kinetic temperature, volume density, and column density from observed CO emission. This method determines the physical conditions of molecular gas with fewer assumptions than other commonly-used methods. I ran the model fitting on the quiescent Molecular Ridge in the LMC, and the resulting volume density shows a much stronger correlation with the presence of young stars than any other easily observed quantity. This suggests that this method is uniquely capable of probing the physical conditions of the molecular gas.
Paper: https://ui.adsabs.harvard.edu/abs/2021ApJ...917..106F/abstract
The Quiescent Molecular Ridge in the LMC
The Quiescent Molecular Ridge in the LMC contains nearly a third of all the molecular gas in the entire galaxy, but is forming surprisingly few massive stars. I measured various properties of the gas clouds in the Ridge and compared them to the properties of clouds in nearby regions of the LMC that are prolifically forming massive stars. I find that the clouds in the Ridge have less kinetic energy and much lower surface densities than the other regions, causing the clouds to be supervirial (their kinetic energy is stronger than the gravitational energy).
Paper: https://ui.adsabs.harvard.edu/abs/2022AJ....164...64F/abstract
RADEX Fitting in N113
I have expanded my RADEX fitting code to fit models to HCO+ and HCN emission as well as CO. For each molecular species, I have created maps of kinetic temperature, column density, and volume density in N113, a site of massive star formation in the LMC.
Paper: In prep.
ALMA-LEGUS: Comaring Gas Conditions in Two Spiral Galaxies
NGC 1313 (above) and NGC 7793 (below) are both spiral galaxies with similar masses, sizes, metallicities, and star formation rates. However, NGC 1313 is forming most of its stars in massive star clusters, whereas NGC 7793 is only forming lower mass clusters. With CO(2-1) observations from ALMA, I am investigating how the conditions of the molecular gas compare between these two galaxies to understand what physical conditions cause large clusters to form.
Paper: Under review.
Elementary Students' Perceptions of Science and Themselves
As part of Dark Skies, Bright Kids (DSBK, see Outreach tab!), I have analyzed student responses to our journal pages and a Draw-A-Scientist-Test. We evaluate how students perceptions of science and themselves change before and after participating in our programming. We find that students are more confident in their science abilities after the program, and that when students are creative, ask questions, and do experiments during camp, they are more likely to see themselves as scientists!
Paper 1: https://ui.adsabs.harvard.edu/abs/2020PRPER..16a0131H/abstract
Paper 2: https://ui.adsabs.harvard.edu/abs/2023arXiv230606014F/abstract