The Life and Times of Star-forming Cores: An Analysis of Dense Gas in the STARFORGE Simulations

Dense gas in molecular clouds is an important signature of ongoing and future star formation. We identify and track dense cores in the starforge simulations, following the core evolution from birth through dispersal by stellar feedback for typical Milky Way cloud conditions. Only similar to 8% of cores host protostars, and most disperse before forming stars. The median starless and protostellar core lifetimes are similar to 0.5-0.6 Myr and similar to 0.8-1.1 Myr, respectively, where the protostellar phase lasts similar to 0.1(-0.05)(+0.1) Myr. While core evolution is stochastic, we find that virial ratios and line widths decline in prestellar cores, coincident with turbulent decay. Collapse occurs over similar to 0.1 Myr, once the central density exceeds greater than or similar to 10(6) cm(-3). Starless cores, only, follow line-width-size and mass-size relations, sigma proportional to R-0.3 and M proportional to R-1. The core median mass, radius, and velocity dispersion scale weakly with the cloud magnetic field strength. We cluster the core properties and find that protostellar cores have >80% likelihood of belonging to three particular groups that are characterized by high central densities, compact radii, and lower virial parameters. Overall, core evolution appears to be universally set by the interplay of gravity and magnetized turbulence, while stellar feedback dictates protostellar core properties and sets the protostellar phase lifetime.