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).

Posts by Collection

proceedings

Evolution of dark matter haloes in CIELO simulations

Published:

This article analyze the dark matter (dm) halo evolution through time. For this study we use a Milky Way like haloes subsample from CIELO (ChemodynamIcal propertiEs of gaLaxies and the cOsmic web) project. This project aims at studying the formation of galaxies in different environments using zoom-ins simulations.

Recommended citation: Cataldi et al. (2023b) https://ui.adsabs.harvard.edu/abs/2023BAAA...64..178C/abstract

publications

Baryons shaping dark matter haloes

Published in MNRAS, 2020

In this work we aim at investigating the effects of baryons on the dark matter haloes structure, focusing on the correlation between the presence and importance of stellar discs and the halo shapes. We study the properties of a subsample of DM haloes from Fenix and eagle cosmological simulations.

Recommended citation: Cataldi, et al. (2020) http://dx.doi.org/10.1093/mnras/staa3988

Fingerprints of modified gravity on galaxies in voids

Published in MNRAS, 2022

In this work, we search for detectable signatures of f(R) gravity and its chameleon screening mechanism in the baryonic and dark matter properties of simulated void galaxies. The enhancement of the gravitational acceleration can have a meaningful impact on the scaling relations as well as on the halo morphology. The galaxy rotational velocity field (calculated with the velocity of the gas disc and the acceleration fields) deviates from the typical values of the Tully-Fisher Relation (TFR) in GR

Recommended citation: Cataldi, et al. (2022) https://doi.org/10.1093/mnras/stac2122

Redshift evolution of the dark matter haloes shapes

Published in MNRAS, 2023

In this work, we aim at investigating the morphology evolution of Milky Way mass-like dark matter haloes selected from the CIELO and IllustrisTNG Projects. The connection between halo shapes and their environment has been studied in previous works at z=0 but their connection remains yet to be fully understood. We focus on the evolution across cosmic time of the halo shapes and the relation with the infalling material, using hydrodynamical simulations

Recommended citation: Cataldi, et al. (2023) https://doi.org/10.1093/mnras/stad1601

Gamma Analytical Modeling Evolution (GAME) I: The physical implications of deriving the stellar mass functions from z=0 to z=8

Published in MNRAS, 2025

The Gamma growth model, characterised by simple parameters, successfully reproduces the evolution of the Galaxy Stellar Mass Function over 13.5 Gyr, with minor deviations at z > 1.5. This suggests that the GSMF’s evolution follows a physically motivated, few-parameter framework consistent with JWST observations.

Recommended citation: Katsianis et al. (2025) https://academic.oup.com/mnras/article/540/1/688/8131524

Galaxy sizes and compactness at Cosmic Dawn

Published in A&A, 2025

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.

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

Halo Occupation Distribution estimation performance for LSST data

Published in A&A, 2026

Upcoming surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will measure galaxy clustering with unprecedented precision. In this project, I develop and test new methods to estimate the halo occupation distribution (HOD)—a key tool that links galaxies to their host dark matter haloes. Using realistic mock catalogues based on the cosmoDC2 simulation, I extend background subtraction techniques to work with photometric data and implement a galaxy group–finding algorithm. This work prepares robust tools to study galaxy clustering and galaxy–halo connections with future LSST observations.

Recommended citation: Cataldi et al. (2026) https://www.aanda.org/articles/aa/abs/2026/08/aa59674-26/aa59674-26.html

The Physical Origins of Scatter in the Dust Attenuation Scaling Relation of Star-Forming Galaxies: Star–Dust Geometry

Published in MNRAS, 2026

Characterising the physical drivers of dust attenuation in star-forming galaxies, Lyu investigates the origin of scatter in the infrared excess (IRX) relation using approximately 32,000 local galaxies from SDSS, GALEX, and WISE. The study shows that deviations from the relation are strongly linked to UV luminosity and can be largely explained by differences in star–dust geometry, including galaxy size and inclination. UV-faint galaxies tend to be compact and edge-on, while UV-bright galaxies are more extended and face-on, highlighting the role of geometry in shaping dust attenuation.

Recommended citation: Lyu et al. (2026) https://ui.adsabs.harvard.edu/abs/2026arXiv260932284L/abstract

talks

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

Published:

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.

The dust attenuation scale relation in TNG50 simulation

Published:

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.

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

Published:

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.

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

Published:

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.

Halo Occupation Distribution estimation performance for LSST Data

Published:

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.

teaching

Teaching Fellow in Physics I

Undergraduate course, . Department of Physics, Buenos Aires University, Faculty of Exact and Natural Sciences, 2017

Analysis II (multivariable calculus), curse 8

Teaching Fellow in Cosmology

Undergraduate course, Department of Physics, Buenos Aires University, Faculty of Exact and Natural Sciences, 2024

Assistant teaching in Cosmology