Dust formation history of galaxies: a critical role of metallicity for
  the dust mass growth by accreting materials in the interstellar medium
  This paper investigate what is the main driver of the dust mass growth in the
interstellar medium (ISM) by using a chemical evolution model of galaxy with
metals (elements heavier than helium) in dust phase in addition to the total
amount of metals. We consider asymptotic giant branch (AGB) stars, type II
supernovae (SNe II) and the dust mass growth in the ISM as the sources of dust,
and SN shocks as the destruction mechanism of dust. Further, to describe the
dust evolution precisely, our model takes into account the age and metallicity
(the ratio of metal mass to ISM mass) dependence of the sources of dust. We
particularly focused on the dust mass growth, and found that the dust mass
growth in the ISM is regulated by the metallicity. To quantify this aspect, we
introduce a "critical metallicity", which is a metallicity at which the
contribution of stars (AGB stars and SNe II) equals that of the dust mass
growth in the ISM. If the star formation timescale is shorter, the value of the
critical metallicity is higher, but the galactic age at which the metallicity
reaches the critical metallicity is shorter. From observations, it was expected
that the dust mass growth was the dominant source of dust in the Milky Way and
dusty QSOs at high redshifts. By introducing the critical metallicity, it is
clearly shown that the dust mass growth is the main source of dust in such
galaxies with various star formation timescales and ages. The dust mass growth
in the ISM is regulated by metallicity, and we stress that the critical
metallicity works as an indicator to judge whether the grain growth in the ISM
is dominant source of dust in a galaxy, especially because of the strong and
nonlinear dependence on the metallicity.
