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Dr. Lucia A. Perez

Computational Astrophysicist & Cosmologist

Learning the Universe with CAMELS-SAM



The Simons Collaboration, Learning the Universe, is working toward one lofty goal: how can we measure the initial conditions of our universe and the physical laws that govern it, given what we're able to observe? How do we get to this using cutting-edge results and progress in: simulations on the biggest and smallest scales, galaxy formation and evolution models, statistical inference and forward modeling, and synthetic observations?

I'm helping us get there by showing this is possible on a small scale, directly on a real observed galaxy sample. CAMELS-SAM is at the heart of the ambitious "LtU Connections" project to build a first-of-its-kind pipeline for simulation based inference of cosmology from the SDSS Main Galaxy Sample. I'm connecting the knowledge and methods of the training set generation group, the implicit likelihood inference group, and the synthetic observations group to do this.

See the figure below for a schematic of how I'm doing this, and check back in often for updates! As of mid-October 2026, I'm working with several folks in the synthetic observations group who are experts of dust modeling and using the Synthesizer code to incorporate the Sommovigo & Bartlett dust model (read more here) to CAMELS-SAM galaxies. This means that the dust modeling will respond to the galaxy formation, too, as has been seen in high resolution simulation projects the team has done -- meaning that our inference can learn from this information too! I'm also leveraging the work I did with a great student to rescale the cosmology of the CAMELS-SAM merger trees directly to add thousands of more galaxy catalogs sampling more cosmologies to our data. Exciting times!

A flowchat; cosmology, into astrophysics, into the observer plane, into a mock survey; and that meets a target survey in inference with ML
how to Learn the Universe with CAMELS-SAM, and trying to do inference on a target survey in the observer plane

Publications


Constraining cosmology with machine learning and galaxy clustering: the CAMELS-SAM suite


Lucia A. Perez, Shy Genel, Francisco Villaescusa-Navarro, Rachel S. Somerville, Austen Gabrielpillai, Daniel Anglés-Alcázar, Benjamin D. Wandelt, L. Y. Aaron Yung

https://arxiv.org/abs/2204.02408


Learning the Universe with Cosmological Rescaling of Merger Trees and Semianalytic Galaxy Formation Models


Richard Stiskalek, Lucia A. Perez, Shy Genel, Rachel S. Somerville, Raul E. Angulo, Sergio Contreras

The Astrophysical Journal, vol. 1007(2), 2026


LtU-ILI: An All-in-One Framework for Implicit Inference in Astrophysics and Cosmology


Matthew Ho, Deaglan J. Bartlett, Nicolas Chartier, Carolina Cuesta-Lazaro, Simon Ding, Axel Lapel, Pablo Lemos, Christopher C. Lovell, T. Lucas Makinen, Chirag Modi, Viraj Pandya, Shivam Pandey, Lucia A. Perez, Benjamin Wandelt, Greg L. Bryan

arXiv e-prints, 2024 Feb, pp. arXiv:2402.05137


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