Pedro Cataldi

Pedro Cataldi

I am a postdoctoral researcher at the Instituto de Astronomía of the Universidad Nacional Autónoma de México (IA-UNAM) in Mexico City. My research focuses on using numerical simulations to study galaxy formation, galaxy sizes, and large-scale structure. I am also a member of the LSST Dark Energy Science Collaboration (DESC).

Galaxy sizes and compactness at Cosmic Dawn

Published in A&A, 2025

Recommended citation: Cataldi et. al. (2026) https://www.aanda.org/articles/aa/full_html/2026/02/aa56078-25/aa56078-25.html

JWST has revealed ultra-compact, massive galaxies at z ≳ 6, challenging current models. Using FirstLight simulations, we find a universal wet compaction phase—an expansion–compaction–re-expansion cycle driven by central baryon domination—that naturally explains the observed inverted size–mass relation at Cosmic Dawn.

Download paper here

Recommended citation: Cataldi et. al. (2026)