Universe@Home

Universe@Home is an astrophysics project that builds synthetic models of stellar populations — whole galaxies worth of stars simulated in aggregate — to understand where compact objects come from. These include neutron stars, stellar-mass black holes, and especially the compact binary systems whose mergers are now routinely detected as gravitational waves by LIGO, Virgo, and KAGRA.

The project runs StarTrack, a population-synthesis code developed by Polish astrophysicist Krzysztof Belczyński. Starting from a stellar population with a chosen initial mass function, metallicity, and binary fraction, StarTrack follows each star through its life — main sequence, red giant, supernova, compact-object formation — applying probabilistic models for mass loss, common-envelope evolution, natal kicks, and dozens of other physical processes. Running these simulations for entire galaxies is computationally intensive but embarrassingly parallel, making it ideal for BOINC.

Universe@Home is hosted by the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, with data archives at the Synthetic Universe portal. Results have directly contributed to our understanding of the progenitors of GW150914 and subsequent gravitational-wave sources, informing observational expectations for LIGO/Virgo/KAGRA's ongoing runs.

Following the death of founder Krzysztof Belczyński in January 2024, the project continues operations under the Nicolaus Copernicus Astronomical Center; its synthetic catalog of black-hole binaries remains an actively referenced resource in gravitational-wave astronomy.