Star Formation Properties of Sloan Digital Sky Survey BOSS Void Galaxies
  in the Hyper Suprime-Cam Survey
  We utilize the Hyper Suprime-Cam (HSC) Wide Survey to explore the properties
of galaxies located in the voids identified from the Baryon Oscillation
Spectroscopic Survey (BOSS) up to z~0.7. The HSC reaches i~25, allowing us to
characterize the void galaxies down to 10$^{9.2}$ solar mass. We find that the
revised void galaxy densities, when including faint galaxies in voids defined
by bright galaxies, are still underdense compared to the mean density from the
entire field. In addition, we classify galaxies into star-forming, quiescent,
and green valley populations, and find that void galaxies tend to have slightly
higher fractions of star-forming galaxies under the mass and redshift control,
although the significance of this result is only moderate (2$\sigma$). However,
when we focus on the star-forming population, the distribution of the specific
star formation rate (sSFR) of void galaxies shows little difference from that
of the control galaxies. Similarly, the median sSFR of star-forming void
galaxies is also in good agreement with that of the star-forming control
galaxies. Moreover, the effective green valley fraction of void galaxies,
defined as the number of green valley galaxies over the number of nonquiescent
galaxies, is comparable to that of the control ones, supporting the suggestion
that void and control galaxies evolve under similar physical processes and
quenching frequencies. Our results thus favor a scenario of the galaxy assembly
bias.
