Pedro Cataldi

Pedro Cataldi

I am a Research Associate 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).

Halo Occupation Distribution estimation performance for LSST Data

September 01, 2026

poster, Probe Combination for Dark Matter Physics in the Era of Large Surveys,, Chicago, US"

We demonstrate the validity of the Background Substracion Technique using a mock galaxy catalogue, recovering the HOD from cosmoDC2 over the absolute magnitude range Mr = -20 to -17 and halo masses up to 1e15 Msun. We present key performance metrics, including completeness and purity, to quantify the precision and reliability of the group finder and the resulting HOD measurements.

Galaxy Formation Across Cosmic Time: From Halo Occupation to Galaxy Structure

August 28, 2026

talk, Weekly Seminar of INAOE, Puebla, Mx"

Upcoming imaging surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will provide high-precision clustering measurements, requiring robust methods to connect galaxies with their dark matter haloes. In the first part of this talk, I will present a method to estimate halo occupation distributions directly from photometric data, adapted for LSST-like observations and tested using the CosmoDC2 mock galaxy catalog. In the second part, I will discuss the origin of extremely compact massive galaxies observed at high redshift by the James Webb Space Telescope. Using the high-resolution FirstLight simulations, we show that galaxies undergo a cycle of expansion, compaction, and re-expansion driven by gas inflows that trigger intense central star formation. This process can naturally produce the very small galaxy sizes observed at $z\gtrsim6$ and suggests the presence of a universal wet-compaction phase during cosmic dawn.

Galaxy Formation and Evolution: From Cosmic Dawn to the LSST Era

August 26, 2026

talk, Weekly Seminar of IA-UNAM, Mexico City, Mx"

In this seminar, I will present three recent works (Cataldi et al. 2026a, 2026b, and Cataldi et al., submitted) dedicated to the study of galaxy formation and evolution using cosmological simulations and their connection with observations. First, I will discuss the origin of the compact galaxies discovered by JWST at high redshifts. In this work, we investigate a possible formation channel for these systems and the evolution of the size–mass relation during the epoch of reionization. In the second part, I will present the development and validation of a technique to estimate the halo occupation distribution (HOD) using photometric information, with the aim of adapting it to the LSST survey of the Vera C. Rubin Observatory. Finally, I will show recent results on dust attenuation in galaxies using the TNG50 cosmological simulation and radiative transfer with SKIRT, assessing its ability to reproduce the observed scaling relations.

The dust attenuation scale relation in TNG50 simulation

July 26, 2026

Talk, 26th Guillermo Haro Workshop 2026, Tonantzintla, Mexico"

This work aims to test the performance of TNG50 simulations and the overall state of the art galaxy simulations in the dust-scale universal relations found by Qin et al 2019, derived from observed star-forming galaxies up to redshift 3.

Introduction to IllustrisTNG: Practical Tools and Example Scripts for Cosmological Simulation Analysi

June 11, 2026

Talk, Advanced Computing and AI Modeling Workshop: Robust Strategies for Science, Puebla, Mexico"

This talk will provide a practical introduction to working with IllustrisTNG and analysing cosmological simulation data using Python. Using a set of analysis tools developed for galaxy studies, I will show common workflows for data analysis, kinematic and morphological decomposition, radial profiles, and visualisation. The goal is to provide participants with practical examples and scripts that can serve as a starting point for their own research projects.