アブストラクト:
"We study the number and the distribution of low mass Pop III stars in
the Milky Way. In our numerical model, hierarchical formation of dark
matter minihalos and Milky Way sized halos are followed by a high
resolution cosmological simulation, which can predict the spatial
distribution of Pop III survivors in the Milky Way. We model the Pop
III formation in H2 cooling minihalos without metal under UV radiation
of the Lyman-Werner bands. Assuming a Kroupa IMF from 0.15 to 1.0 Msun
for low mass Pop III stars, as a working hypothesis, we try to
constrain the theoretical models in reverse by current and future
observations. We find that the number of survivors is proportional to
the halo mass and the number of Pop III per minihalo. Thus, the
distribution of survivors reflects that of dark matter and the
survivors tend to concentrate on the center of halo and subhalos. We
also evaluate the observability of Pop III survivors in the Milky Way
and dwarf galaxies, and constraints on the number of Pop III survivors
per minihalo. The higher latitude fields require lower sample sizes
because of the high number density of stars in the galactic disk, the
required sample sizes are comparable in the high and middle latitude
fields by photometrically selecting low metallicity stars with
optimized narrow band filters, and the required number of dwarf
galaxies to find one Pop III survivor is less than ten at <100 kpc for
the tip of redgiant stars. Provided that available observations have
not detected any survivors,
the formation models of low mass Pop III stars with more than ten
stars per minihalos are already excluded."