LYRA

I have been developing LYRA since 2019. It follows the interstellar medium in all its phases, down to 10 K. Stars form individually, sampled from the initial mass function, and each one's lifetime and fate is tracked. Every supernova explodes as its own blast wave, with variable energy, inside the hydrodynamic calculation.

At our fiducial resolution of 4 solar masses per gas cell, most supernovae are resolved. Their feedback builds a hot phase in the interstellar medium on its own, drives strong outflows, and regulates star formation. Clustered supernovae turn out to matter most: the majority explode into low-density gas, where they are far more effective.

LYRA makes it possible to run this detailed interstellar medium model directly in cosmological zoom-in simulations of dwarf galaxies and beyond.

The first cosmological LYRA run (Gutcke et al. 2022) follows a dwarf galaxy in a 2×10⁹ solar-mass halo all the way to the present day. The resulting galaxy matches the stellar mass, size, kinematics and metallicity of Local Group dwarfs, and it shows that where the very first stars form shapes how a dwarf galaxy assembles.

• Self-interacting dark matter in LYRAGutcke et al. 2026
• Dark matter and baryons in LYRASureda et al. 2026
• LYRA ultra-faint dwarfsBrown et al. 2026
• Globular cluster formation in LYRA dwarfsGutcke 2024
• A suite of five dwarf galaxiesGutcke et al. 2022b
• Cosmological LYRAGutcke et al. 2022a
• The method paperGutcke et al. 2021

LYRA was initially developed by Thales A. Gutcke at the Max-Planck-Institute for Astrophysics in Garching with support from Volker Springel, Rüdiger Pakmor and Thorsten Naab.

More recently, some improvements and analysis is being carried out by Azadeh Fattahi's group at Stockholm University. Initial conditions were created at the Institute for Computational Cosmology, Durham University by Adrian Jenkins, Ashley J. Kelly and Azadeh Fattahi.

LYRA is a Virgo Consortium project. If you'd like to take part, get in touch.