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 initial conditions of local three dimensional radiation
hydrodynamics simulations to investigate the formation of the first stars. We
find two-thirds of the minihalos host multiple stars, while the rest of them
have single stars. The mass of the stars found in our simulations are in the
range of 1 Msun \la M \la 300 Msun, peaking at several x 10 Msun. Most of the
very massive stars of \ga 140 Msun are born as single stars, although not all
of the single stars are very massive. We also find a few stars of \la 1 Msun
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 \sim 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 Lyman-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.
