AGORA High-resolution Galaxy Simulations Comparison Project

Welcome to the AGORA Project (Assembling Galaxies Of Resolved Anatomy)! We investigate galaxy formation with high-resolution simulations and compare the results across code platforms and with observations. This is an one-of-a-kind, inter-institutional effort by more than 160 participants from over 60 institutions worldwide (as of 2021). We welcome anybody who is interested in participating in the Project. Click the image on the right to see an 1-slide introduction to the Project.

This research uses resources of the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility. We also thank the support from the University of California High-Performance AstroComputing Center and the National Science Foundation.


● The 3rd paper of the Project ("Cosmological run") was published in ApJ in 2021: [ADS] [arXiv] [local/high-res]

● The 2nd paper of the Project ("Disk run") was published in ApJ in 2016: [ADS] [arXiv] [local/high-res]

● The 1st paper of the Project ("Flagship paper") was published in ApJS in 2014: [ADS] [arXiv] [local/high-res] [press release]

● The 9th annual Workshop of the Project is expected to be held online on Aug. 12-13 (tentative), 2021. Stay tuned!

● The 8th annual Workshop of the Project was held at UC Santa Cruz on Aug. 9-10, 2019.

● Click the News tab above to read more news.

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● AGORA Project goals and rationale. For details, see the Project's Flagship paper (ADS, arXiv, press release). [Read more]

In the AGORA Project (Assembling Galaxies Of Resolved Anatomy; formerly known as Santa Cruz High-resolution Galaxy Simulation Comparison Project), we aim to:

  • Inaugurate a lasting infrastructure for comparing high-resolution galaxy formation simulations across different high-resolution numerical platforms

  • Establish isolated and cosmological initial conditions so each participating group can run a suite of simulations in the coming years

  • Invite (but not require) each of the participating code groups to perform two types of high-resolution galaxy formation simulations (isolated galaxy and cosmological zoom-in galaxy) with resolution of ~100 parsecs

  • Analyze and compare the resulting simulations at several epochs and in multiple dimensions; at the end, go a step further to include comparisons with observational data

  • Focus on science-based, multi-platform research, rather than merely an one-time code comparison; use this project as a springboard to launch many science-oriented comparison endeavors

  • Raise the predictive power of the numeircal galaxy formation collectively

  • Maintain healthy and vibrant collaboration through annual workshops, and online meetings between them

Early history and rationale:

  • AGORA Project was launched during its 1st Workshop in 2012 at UC Santa Cruz. The initial project infrastructures were built and the proof-of-concept simulations were carried out in 2012-2013, which led us to achieve its first measurable objective in late 2013, the Project's "Flagship paper" (published in 2014).

  • All the main simulation groups in the world were represented (in many cases by their leaders), and through extremely constructive discussion we were able to reach consensus on a wide variety of key issues. These include common initial conditions for cosmological zoom-in simulations and isolated disk simulations, common physics packages such as ultraviolet background and cooling functions, and common analysis tools including yt.

  • People have signed up to be key contacts for all the simulation groups, titles and topics of the major papers to be produced by the Project were agreed upon with at least one person tentatively agreeing to take charge of each.

  • It is remarkable that we have launched this project at the time when several key technologies have just become available including the simulation codes, the MUlti-Scale Initial Conditions generator (MUSIC) for simulation ICs, and the yt code for analyzing the outputs from many simulations. This project will be state-of-the-art in every respect, and in fact will advance the entire field of galaxy simulations.


● We have formed 4 task-oriented working groups and 9 science-oriented working groups, along with a Project Steering Committee. We have also formed several "paper groups" with multiple working groups engaged to report our research in articles. [Read more]

Task-oriented Working Groups (I-IV): click the Groups tab to learn more

  • Working Group I - Common Physics and Introduction to Project

  • Working Group II - Common ICs: Isolated

  • Working Group III - Common ICs: Cosmological

  • Working Group IV - Common Analysis

Science-oriented Working Groups (V-XIII): click the Groups tab to learn more

  • Working Group V - Isolated Galaxies and Subgrid Physics

  • Working Group VI - Dwarf Galaxies in Cosmological Simulations

  • Working Group VII - Dark Matter

  • Working Group VIII - Satellite Galaxies

  • Working Group IX - Characteristics of Cosmological Galaxies

  • Working Group X - Outflows

  • Working Group XI - High-redshift Galaxies

  • Working Group XII - Interstellar Medium

  • Working Group XIII - Black Hole Accretion and Feedback

Examples of Paper Groups: click the Groups tab to learn more

  • Paper Group "Flagship"

  • Paper Group "Disk"

  • Paper Group "CosmoRun"

+ many more

AGORA Steering Committee

  • Tom Abel (Stanford University)

  • Nick Gnedin (Fermilab)

  • Piero Madau (University of California at Santa Cruz)

  • Lucio Mayer (University of Zurich)

  • Joel Primack (University of California at Santa Cruz)

  • Romain Teyssier (University of Zurich)

  • James Wadsley (McMaster University)

+ Ji-hoon Kim (Seoul National University, Project Coordinator)


● The cohort of numerical codes that have shown interest in participating in the Project include (but are not limited in future studies to) the following. Each participating code is represented by point persons who volunteered to be liaisons for isolated and/or cosmological simulations. Participating codes that are in the actual comparison may differ in each paper. [Read more]

AREPO: [to be confirmed]

ART-I (NMSU): Daniel Ceverino, Anatoly Klypin, Santi Roca-Fabrega, Sebastian Trujillo-Gomez

ART-II (Chicago): Robert Feldmann, Nick Gnedin, Sam Leitner

CHANGA: Johnny Powell, Tom Quinn, Hector Velazquez, Spencer Wallace

ENZO: Mike Butler, John Forbes, Ji-hoon Kim, Christine Simpson, John Wise

GADGET-2/3/4: Junhwan Choi, Ken Nagamine, Jose Onorbe, Miguel Rocha, Ikkoh Shimizu, Keita Todoroki

GADGET-SPHS: Alexander Hobbs, Justin Read

GASOLINE: Ben Keller, Sijing Shen, James Wadsley

GCD+: Daisuke Kawata

GEAR: Loic Hausammann, Yves Revaz

GIZMO/P-SPH: Philip Hopkins, Alessandro Lupi

NYX: Wolfram Schmidt (isolated runs only)

PKDGRAV-2: Javiera Guedes, Mike Kuhlen (cosmological runs only)

RAMSES: Oscar Agertz, Oliver Hahn, Santi Roca-Fabrega, Romain Teyssier


● Want to join the AGORA Collaboration? Want to use the AGORA ICs, simulation datasets, and more? [Read more]

If you are looking for the AGORA common initial conditions (ICs), examples of common analysis yt scripts used in the Project, or the isolated galaxy simulation snapshots produced by AGORA, click the Tools+Data tab above.

Consider joining the Collaboration with no obligation, especially if you want to learn more about the AGORA common ICs and analysis scripts used in the Project. Simply send an email to the Project coordinator. Contact us if you have any other question, too!