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.

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Andrew Benson

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.

The Galacticus model

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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Constraining dark matter microphysics

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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Synthetic skies for next-gen surveys

Surveys

Synthetic skies for next-gen surveys

Building galaxy mocks for the Roman GRS Project Infrastructure Team and the NASA Open Universe initiative.

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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.

Figure from A Graph-based Neural-network Surrogate Model for an Accelerating Semianalytical Model of Galaxy Formation and Evolution

The Astrophysical Journal Supplement Series 2026

A Graph-based Neural-network Surrogate Model for an Accelerating Semianalytical Model of Galaxy Formation and Evolution

Li, Xuejie, A. Benson, et al.

A neural network that works directly on the branching histories of dark matter halos reproduces the galaxy properties predicted by a full semi-analytic model — stellar mass, luminosity, rotation, gas metal content, and star formation rate — over the first twelve billion years of cosmic time, matching stellar masses to within 0.19 to 0.28 dex. A single such surrogate holds up across different model parameter choices and halo histories, offering a fast stand-in when exploring the parameter space of galaxy formation models.

ADS · arXiv · DOI

Figure from The Curious Case of Centaurus A: On the Subject of the Quenched satellites

The Open Journal of Astrophysics 2026

The Curious Case of Centaurus A: On the Subject of the Quenched satellites

Weerasooriya, Sachi, A. Benson, et al.

Models calibrated to the Milky Way overpredict the number of bright satellite galaxies within 150 kpc of Centaurus A by a factor of four, and chance alone cannot account for the shortfall. The missing satellites occupy the same region as Centaurus A's kiloparsec-scale radio lobes, and heating driven by the host's central black hole can suppress star formation in them enough to explain the deficit.

ADS · arXiv · DOI

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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 →