Fabio De Colle

Astrophysicist, specializing in high-energy and computational astrophysics.

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Fabio De Colle - Astrophysicist

Researcher at the Instituto de Ciencias Nucleares (UNAM, Mexico City), specializing in numerical simulations of high-energy astrophysical phenomena.

My work focuses on high energy transients, in particular gamma-ray bursts (GRBs), core-collapse supernovae, and tidal disruption events (TDEs)—some of the most energetic processes in the universe.

I develop computational methods such as adaptive mesh refinement (AMR) and moving mesh techniques to model fluid dynamics, magnetic fields, and radiation in extreme conditions. My work involves newtonian and relativistic hydrodynamics and magnetohydrodynamics (MHD).

Recently, I have incorporated machine learning and data science techniques to enhance both simulation analysis and physical modeling.

Curriculum Vitae

Numerical astrophysicist working mainly on high-energy transients.

Professional Experience

2012 – Present

Researcher — UNAM, Mexico

  • Numerical simulations of high-energy astrophysical transients
  • SNI III, Titular C
2009 – 2012

Postdoctoral Researcher — UCSC, USA

  • Relativistic jet simulations (GRBs, TDEs)
2006 – 2008

Marie Curie Postdoc — Dublin Institute for Advanced Studies

  • Protostellar and HH jet simulations

Education

2003 – 2005

PhD in Astrophysics — UNAM

Thesis: Jets and disks around young stars (with honours)

2001 – 2003

MSc in Astrophysics — UNAM

1993 – 1999

Laurea in Physics — Università dell'Insubria

Thesis: SF6 plasma diagnostics and modeling — 110/110 cum laude

Research

My research focuses on relativistic astrophysics, emphasizing the physics of jets and high-energy transients such as gamma-ray bursts (GRBs), supernovae (SNe), tidal disruption events (TDEs), and common envelopes (CEs). I combine large-scale numerical simulations and high-performance computing to study their dynamics, radiation, and interaction with complex environments.

A central component of my work is the development of the Mezcal simulation code, a high-performance framework for newtonian and relativistic hydrodynamics and magnetohydrodynamics, using adaptive mesh refinement (AMR) and MPI parallelization.

GRBs

Gamma-ray Bursts

I study relativistic jets in GRBs, focusing on the cocoon structure, off-axis emission, and afterglow physics. My work combines numerical simulations with observational constraints to understand jet dynamics and radiation mechanisms.

Supernovae

Supernovae

My work explores supernova interaction with circumstellar material, including connections to relativistic jets and GRBs.

Numerical Simulations

Numerical Simulations & Code Development

I develop high-performance simulation codes for newtonian and relativistic flows, including hydrodynamics and magnetohydrodynamics. My work focuses on scalable algorithms using AMRa and MPI to model complex astrophysical systems.

TDEs

Jets in Tidal Disruption Events

I study jet dynamics and emission in tidal disruption events, focusing on ther dynamics and high-energy radiation.

Relativistic Jets

Jets in Common envelopes

I investigate the accretion process and jet propagation in common envelopes, and their role to shape the CE evolution. These studies are relevant for understanding the formation of compact binaries and gravitational wave sources.

Herbig-Haro Jets

Herbig-Haro Jets

I have studied jets from young stellar objects, focusing on their interaction with the surrounding medium and emission properties.

Students & Postdocs

I supervise undergraduate, master's, and PhD students in relativistic astrophysics. Projects include simulations of astrophysical transients, relativistic jets, supernovae, radiation processes. I also welcome students interested in computational methods and machine learning applications in astrophysics.

Former students have continued to PhD programs and postdoctoral positions in astrophysics.

Current Students

Jesus Carrillo - co-supervisor
PhD — UNAM
Common Envelopes
Jhonnayker Paredes
PhD — UNAM
Non-thermal particle emission
Carla Chavez
Undergraduate - UNAM
Parallelization of CFD codes using graph theory

Former Students and postdoctoral researchers

Postdoctoral Researchers
  • Rosa Becerra — GRB observations with robotic telescopes (2020–2023)
PhD Students
Master's Students
Undergraduate Students

Teaching

Courses I have taught:

Graduate Courses

Advanced topics in high-energy astrophysics, stellar astrophysics, and computational fluid dynamics.

  • Stellar astrophysics (from 2017 to 2026, once a year)
  • High energy astrophysics (2016)
  • Computational astrophysics (2016, 2020)
  • Physics of gamma-ray bursts (2014, 2017, 2020, 2023)
  • Radiative processes in astrophysics (2015, 2016, 2026)

Undergraduate Courses

Introductory and advanced undergraduate courses in astrophysics, computational methods, and numerical simulations at UNAM

  • Computational astrophysics (2024)
  • High energy astrophysics (2013, 2018)

Latest Publications

Recent publications and submitted manuscripts from last year. See the complete publication list below.

Two-dimensional density structure of a relativistic tidal disruption event jet
Two-dimensional density structure of a continuously powered relativistic tidal disruption event jet. Sustained energy injection produces a different jet structure from the standard impulsive blast-wave picture.
In press 2026

Beyond the Impulsive Approximation: The Dynamics and Radio Emission of Tidal Disruption

De Colle, F. & Ramirez-Ruiz, E.

ApJL, in press

Relativistic tidal disruption event jets are powered by fallback accretion over weeks to months, rather than by a single impulsive explosion. Using relativistic hydrodynamic simulations coupled to synchrotron radiation calculations, we show that sustained energy injection produces slower shocks and substantially fainter radio emission than predicted by the standard impulsive approximation.

01

Slower and fainter. Fallback-powered jets produce slower forward shocks and delayed, systematically weaker radio emission.

02

The impulsive approximation breaks down. It is valid only when energy injection lasts less than roughly 10% of the deceleration time.

03

Off-axis emission is strongly suppressed. Sustained jets are less beamed, suggesting that relativistic jets in TDEs may be more common than radio observations imply.

ADS ↗
Radio synchrotron emission from an unresolved transient
Schematic illustration of how inhomogeneities in an unresolved shock modify the observed synchrotron spectrum.
Submitted 2026

Constraining Inhomogeneities and Asymmetries in SNe, FBOTs, and Other High-Energy Transients from Unresolved Radio Observations

De Colle, F., Becerra, R., Meza Gónzalez, L., et al.

MNRAS, submitted

Radio synchrotron spectra provide a powerful probe of high-energy transients, even for spatially unresolved sources. We show that deviations from the standard synchrotron self-absorption spectrum can be used to infer the degree of inhomogeneity and asymmetry of the emitting region directly from unresolved radio observations.

01

Structure from an unresolved source. The shape of a synchrotron self-absorption spectrum can reveal information about the spatial structure of the emitting region even when it cannot be directly imaged.

02

SN 2016coi and AT2018cow reveal different structures. The method provides evidence for strong inhomogeneities in SN 2016coi and asymmetry in the emitting region of AT2018cow.

03

A general diagnostic for high-energy transients. With well-sampled radio spectra, the method can constrain inhomogeneities in unresolved SNe, FBOTs, TDEs, and GRBs without relying on a detailed geometric model.

ADS ↗
Magnetic interaction between a planet and its host star
Current-density streamlines around the planet, revealing the complex magnetic structure generated by the planetary interaction.
Published 2025

Numerical Simulations of the Interaction Between the Stellar Magnetic Field and a Planet

De Colle, F., Lin, D.N.C., Chen, C., & Li, G.

MNRAS, Vol. 539, pp. 3459–3472, 2025

Ultrashort-period super-Earths orbit extremely close to young, strongly magnetized stars. We investigate how magnetic interactions between the stellar wind and non-magnetized planets can remove orbital angular momentum and drive their long-term orbital evolution. Combining magnetic torque calculations with models of stellar spin-down and magnetic-field decay, we determine the conditions under which these planets can survive.

01

Magnetic drag modify substantially planetary orbits. Interaction between the stellar wind and the planet exerts a torque that can modify the planet's orbital evolution.

02

Young stars matter. Strong kiloGauss magnetic fields during the early evolution of G-, K-, and M-type stars can produce significant orbital torques on close-in planets.

03

Not all ultrashort-period planets survive. The evolution of stellar rotation and magnetic-field strength defines which close-in super-Earths can remain on stable orbits.

ADS ↗

Publications

I have published 86 papers, 54 (~63%) as first, second or third author. You can find my full publication list below (divided into categories) or from the ADS.

GRBs (32 papers)

Lead-author and student-lead (12)
Major Contributions (2nd or 3rd Author) (10)
Collaborations (10)

SNe & SNR (20 papers)

Lead-author and student-lead (2)
Major Contributions (2nd or 3rd Author) (3)
Collaborations (15)

CEs (7 papers)

Lead-author and student-lead (1)
Major Contributions (2nd or 3rd Author) (6)

TDEs (7 papers)

Lead-author and student-lead (3)
Collaborations (4)

HH jets and star formation (16 papers)

Lead-author and student-lead (7)
Major Contributions (2nd or 3rd Author) (5)
Collaborations (4)

Fluids and shocks (9 papers)

Lead-author and student-lead (2)
Major Contributions (2nd or 3rd Author) (5)
Collaborations (3)

Contact

Office

Instituto de Ciencias Nucleares, UNAM
Ciudad Universitaria, Mexico City

Email

fabio [at] nucleares.unam.mx