THE MASS SPECTRUM OF THE FIRST STARS

We perform cosmological hydrodynamics simulations with non-equilibrium primordial chemistry to obtain 59 minihalos that host first stars. The obtained minihalos are used as the initial conditions of local three-dimensional radiation hydrodynamics simulations to investigate the formation of the first stars. We find that two-thirds of the minihalos host multiple stars, while the other third has single stars. The mass of the stars found in our simulations are in the range of 1 M-circle dot less than or similar to M less than or similar to 300 M-circle dot, peaking at several x 10 M-circle dot. Most of the very massive stars of greater than or similar to 140 M-circle dot are born as single stars, although not all of the single stars are very massive. We also find a few stars of less than or similar to 1 M-circle dot that are kicked by the gravitational three body interactions to the position distant from the center of mass. The frequency that a star forming minihalo contains a binary system is similar to 50%. We also investigate the abundance pattern of the stellar remnants by summing up the contributions from the first stars in the simulations. Consequently, the pattern is compatible with that of the low metallicity damped Ly alpha systems or the extremely metal-poor (EMP) stars, if the mass spectrum obtained in our experiment is shifted to the low mass side by 0.2 dex. If we consider the case that an EMP star is born in the remnant of the individual minihalo without mixing with others, the chemical signature of the pair instability supernova is more prominent, because most of them are born as single stars.