Abstract
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.
Highlights
Stellar light, in particular at shorter wavelengths, is absorbed by dust and re-emitted as a far-infrared thermal emission from the dust (e.g., Witt and Gordon, 2000, and references therein)
In this work, we have constructed a galaxy evolution model taking into account the metallicity and age dependence on the various dust sources (AGB stars, SNe II and growth in the interstellar medium (ISM)) to investigate what is the main driver of the grain growth which is expected to be the dominant source of dust in various galaxies with various starformation timescales
We have found that the point at which the dust mass growth in the ISM becomes dominant is determined by the metallicity
Summary
In particular at shorter wavelengths, is absorbed by dust and re-emitted as a far-infrared thermal emission from the dust (e.g., Witt and Gordon, 2000, and references therein). Dust affects the spectral energy distributions of galaxies (e.g., Takagi et al, 1999; Granato et al, 2000; Noll et al, 2009; Popescu et al, 2011). The existence of dust in galaxies affects the star-formation activity. Star formation is activated drastically by dust. Dust is one of the most important factors for the evolution of galaxies (e.g., Hirashita and Ferrara, 2002; Yamasawa et al, 2011)
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