We describe a population of young star clusters ( SCs ) formed in a hydrodynamical simulation of a gas-rich dwarf galaxy merger resolved with individual massive stars at sub-parsec spatial resolution .
The simulation is part of the griffin ( Galaxy Realizations Including Feedback From INdividual massive stars ) project .
The star formation environment during the simulation spans seven orders of magnitude in gas surface density and thermal pressure , and the global star formation rate surface density ( \Sigma _ { \mathrm { SFR } } ) varies by more than three orders of magnitude during the simulation .
Young SCs more massive than M _ { \mathrm { *,cl } } \sim 10 ^ { 2.5 } M _ { \odot } form along a mass function with a power-law index \alpha \sim - 1.7 ( \alpha \sim - 2 for M _ { \mathrm { *,cl } } \gtrsim 10 ^ { 3 } M _ { \odot } ) at all merger phases , while the normalization and the highest SC masses ( up to \sim 10 ^ { 6 } M _ { \odot } ) correlate with \Sigma _ { \mathrm { SFR } } .
The cluster formation efficiency varies from \Gamma \sim 20 \% in early merger phases to \Gamma \sim 80 \% at the peak of the starburst and is compared to observations and model predictions .
The massive SCs ( \gtrsim 10 ^ { 4 } M _ { \odot } ) have sizes and mean surface densities similar to observed young massive SCs .
Simulated lower mass clusters appear slightly more concentrated than observed .
All SCs form on timescales of a few Myr and lose their gas rapidly resulting in typical stellar age spreads between \sigma \sim 0.1 - 2 Myr ( 1 \sigma ) , consistent with observations .
The age spreads increase with cluster mass , with the most massive cluster ( \sim 10 ^ { 6 } M _ { \odot } ) reaching a spread of 5 \mathrm { Myr } once its hierarchical formation finishes .
Our study shows that it is now feasible to investigate the SC population of entire galaxies with novel high-resolution numerical simulations .