Theoretical Astrophysicist · Carnegie Observatories
Andrew Benson
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
What I work on
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
The Galacticus model
An open-source semi-analytic model of galaxy formation used to interpret observations across cosmic time.
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Dark matter
Constraining dark matter microphysics
Using halo substructure, gravitational lensing, and dwarf galaxies to test warm, self-interacting, and other non-CDM models.
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Surveys
Synthetic skies for next-gen surveys
Building galaxy mocks for the Roman GRS Project Infrastructure Team and the NASA Open Universe initiative.
Read more →Recent work
Selected recent papers
These cards are rebuilt automatically from my NASA ADS library on a weekly schedule. Summaries and figures are generated from the paper itself.
Correlation between Baryonic Process and Galaxy Assembly Bias
For galaxies picked by their mass in stars, the extra clustering that depends on more than the mass of their dark matter halos tracks most closely how gas cools and how stars blow gas back out, regardless of how common the galaxies are. For galaxies picked by how fast they form stars, the most closely linked process shifts from star formation itself to gas cooling as the sample includes more common galaxies.
JWST lensed quasar dark matter survey. III. Dark matter sensitive flux ratios and warm dark matter constraint from the full sample
Infrared images of the warm dust around 31 multiply imaged quasars, taken with JWST, double the sensitivity to a cutoff in the number of low-mass dark matter clumps relative to earlier work, and show no sign of one down to about 10^7.8 solar masses. That implies dark matter particles produced thermally in the early universe must be heavier than roughly 6 keV.
Open source
Galacticus
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 →