Category: article

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second public data release of the FIRE-2 simulations

With our second public data release, we have released nearly every FIRE-2 simulation, with nearly every snapshot for each simulation.

In Wetzel et al 2025, we describe the second public data release (DR2) of the FIRE-2 simulations, available at flathub.flatironinstitute.org/fire. DR2 contains nearly every available snapshot from 119 simulations, spanning massive to Milky Way-mass to ultra-faint galaxies, with up to 601 snapshots each across z = 0 to 99, as well as halo/galaxy catalogs with full merger trees, particle tracking, and 3-D formation coordinates for all star particles. DR2 also includes physics variations, including dark-matter-only resimulations, resimulations with a modified ultraviolet background, and resimulations with magnetohydrodynamics (MHD) and cosmic rays.

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public data release of the FIRE-2 simulations

Nearly all of our FIRE-2 cosmological zoom-in simulations of galaxy formation are now publicly available!

In Wetzel et al 2023 we describe the first public data release (DR1) of the FIRE-2 simulations, available at flathub.flatironinstitute.org/fire. DR1 contains full snapshots from 46 different simulations, spanning massive to Milky Way-mass to ultra-faint galaxies, with up to 39 snapshots each across z = 0 to 10, as well as halo/galaxy catalogs, particle tracking, 3-D formation coordinates for each star particle, and additional data products. We provide a comprehensive description of the FIRE-2 simulations and data products, and we describe various publicly available Python analysis packages to make using these simulations easier.

This DR1 extends our initial data release (DR0) of a subset of FIRE-2 simulations, which contained complete snapshots of 3 of our Latte simulations of Milky Way-like galaxies at z = 0, accompanied by our Ananke synthetic Gaia DR2-like surveys that we created from these simulations (Sanderson et al 2020), which are available via yt Hub at ananke.hub.yt.

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Sky & Telescope article: plane of satellites

The Alignment of the Milky Way’s Entourage, Explained

Sky & Telescope highlighted our recent research in their article: The Alignment of the Milky Way’s Entourage, Explained. PhD student Jenna Samuel led this work, to understand the origin of the thin plane of satellite galaxies around the Milky Way, including the likely important role that the Large Magellanic Cloud has played in causing this planar structure.

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first student-led paper from our group: radial distribution of satellite galaxies

Radial distance distribution of satellite galaxies around MW-mass galaxies in the FIRE-2 simulations, as compared with the MW and M31

We are excited to announce the first student-led paper from our group, from PhD student Jenna Samuel: A profile in FIRE: resolving the radial distributions of satellite dwarf galaxies in the Local Group with simulations. Jenna examined the radial distance distribution of satellite galaxies around MW/M31-mass galaxies in our FIRE simulations, which she showed are consistent with the Local Group and with MW-like galaxies from the SAGA survey. Interestingly, more massive host galaxies have fewer satellites at small distances, because of tidal destruction from the host galaxy. Jenna also quantified the destruction of subhalos by comparing our baryonic simulations to their dark matter-only versions, finding 10x fewer subhalos within the inner 20 kpc. Finally, Jenna applied observational completeness within the LG to our simulations, predicting 2-10 more satellites with stellar mass > 1e5 Msun to be discovered around the MW and 6-9 around M31. Congratulations to Jenna for an excellent first paper!

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Ananke: synthetic Gaia surveys

synthetic Gaia DR2-like surveys from the Latte suite of FIRE-2 cosmological simulations of Milky Way-mass galaxies

We are excited to announce the release of our synthetic Gaia DR2-like surveys from our Latte suite of FIRE-2 cosmological simulations of Milky Way-mass galaxies. We generated 9 synthetic surveys from 3 simulations, using 3 solar viewpoints per simulation.  Along with these synthetic surveys, we also released the full simulation snapshots, including all particle data. All data is available at , and the paper that describes our methods is Sanderson et al 2020.

Congratulations to Robyn Sanderson for leading this ambitious effort, including developing our new Ananke framework for generating synthetic surveys from baryonic simulations. Thanks to Kacper Kowalik and Matt Turk for help hosting this data via the awesome .

We hope that these cosmological synthetic Gaia DR2-like surveys will provide useful tools to the scientific community in interpreting the amazing data of the Milky Way from the Gaia space telescope.