Theoretical Astrophysicist · Carnegie Observatories
I am a Staff Scientist at the Carnegie Observatories. My research is focused on understanding the nature of dark matter and the process of galaxy formation — combining analytic models, numerical simulations, and large astronomical surveys.
Research focus
Three threads tie my research together: building a coherent theoretical model of galaxy formation; constraining the microphysics of dark matter; and designing the synthetic universes that next-generation surveys need to interpret their data.
Galaxy formation
An open-source semi-analytic model of galaxy formation used to interpret observations across cosmic time.
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Dark matter
Using halo substructure, gravitational lensing, and dwarf galaxies to test warm, self-interacting, and other non-CDM models.
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Surveys
Building galaxy mocks for the Roman GRS Project Infrastructure Team and the NASA Open Universe initiative.
Read more →Recent work
These cards are rebuilt automatically from my NASA ADS library on a weekly schedule. Summaries and figures are generated from the paper itself.
This research develops a more accurate model for predicting gaps in stellar streams caused by dark matter substructures, finding that the number of expected gaps is significantly higher than previously estimated. This advancement enhances the potential of stellar streams as tools for probing dark matter properties.
This study establishes a new upper limit on the minimum halo mass in cold dark matter models, finding it to be less than \(10^{8.3}\) solar masses using strong gravitational lensing data. The results indicate that future observations of more lensed quasars could significantly refine our understanding of dark matter structures in the universe.
This study reveals that self-interacting dark matter (SIDM) halos around the Milky Way and M31 can bypass typical core formation, leading to increased central densities during close encounters. The findings highlight a structural dichotomy, where the compact stellar components are resilient to tidal disruptions, while the diffuse stellar halo is more vulnerable, emphasizing the complex dynamics of galaxy interactions in the Local Group.
This study finds strong agreement between observed stellar mass growth in early galaxies and predictions from the GALACTICUS model, highlighting the importance of stellar mass as a fundamental measure in galaxy formation. The results suggest that significant in situ growth and mergers contributed to stellar mass increases during the early universe, challenging previous claims about the dominance of star formation bursts.
The THESAN project reveals that the timing of cosmic reionization in Local Group analogues is significantly influenced by their surrounding environment, with denser regions ionizing earlier. This research enhances understanding of how large-scale structures affect reionization, providing insights into the early histories of galaxies like the Milky Way.
This study compares warm dark matter subhalo populations from two different modeling approaches, finding that both predict a reduction in low-mass subhalos as WDM particle mass decreases. The results indicate that the semi-analytic model Galacticus can effectively replicate the distributions observed in N-body simulations, providing a valuable tool for further research on warm dark matter's effects in astrophysics.
Open source
Most of my modeling work happens inside Galacticus, an open-source semi-analytic model of galaxy formation that I wrote and continue to develop. It's used by groups around the world to study dark matter, galaxy evolution, and forecast observations for upcoming surveys. See the full software stack →