Radiative Regulation of Population III Star Formation
  We explore the impact of ultraviolet (UV) radiation from massive Population
III (Pop III) stars of 25, 40, 80, and 120 M_sun on the subsequent Pop III star
formation. In this paper, particular attention is paid to the dependence of
radiative feedback on the mass of source Pop III star. UV radiation from the
source star can work to impede the secondary star formation through the
photoheating and photodissociation processes. Recently, Susa & Umemura (2006)
have shown that the ionizing radiation alleviates the negative effect by
H_2-dissociating radiation from 120$M_sun PopIII star, since an H_2 shell
formed ahead of an ionizing front can effectively shield H_2-dissociating
radiation. On the other hand, it is expected that the negative feedback by
H_2-dissociating radiation can be predominant if a source star is less massive,
since a ratio of the H_2-dissociating photon number to the ionizing photon
number becomes higher. In order to investigate the radiative feedback effects
from such less massive stars, we perform three-dimensional radiation
hydrodynamic simulations, incorporating the radiative transfer effect of
ionizing and H_2-dissociating radiation. As a result, we find that if a source
star is less massive than ~25M_sun, the ionizing radiation cannot suppress the
negative feedback of H_2-dissociating radiation. Therefore, the fate of the
neighboring clouds around such less massive stars is determined solely by the
flux of H_2-dissociating radiation from source stars. With making analytic
estimates of H_2 shell formation and its shielding effect, we derive the
criteria for radiation hydrodynamic feedback depending on the source star mass.
