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Modelling Dust Evolution in Galaxies with a Multiphase, Inhomogeneous ISM
- Publication Year :
- 2016
-
Abstract
- We develop a model of dust evolution in a multiphase, inhomogeneous ISM including dust growth and destruction processes. The physical conditions for grain evolution are taken from hydrodynamical simulations of giant molecular clouds in a Milky Way-like spiral galaxy. We improve the treatment of dust growth by accretion in the ISM to investigate the role of the temperature-dependent sticking coefficient and ion-grain interactions. From detailed observational data on the gas-phase Si abundances [Si/H]_{gas} measured in the local Galaxy, we derive a relation between the average [Si/H]_{gas} and the local gas density n(H) which we use as a critical constraint for the models. This relation requires a sticking coefficient that decreases with the gas temperature. The synthetic relation constructed from the spatial dust distribution reproduces the slope of -0.5 of the observed relation in cold clouds. This slope is steeper than that for the warm medium and is explained by the dust growth. We find that it occurs for all adopted values of the minimum grain size a_{min} from 1 to 5nm. For the classical cut-off of a_{min}=5 nm, the ion-grain interactions result in longer growth timescales and higher [Si/H]_{gas} than the observed values. For a_{min} below 3 nm, the ion-grain interactions enhance the growth rates, steepen the slope of [Si/H]_{gas}-n(H) relation and provide a better match to observations. The rates of dust re-formation in the ISM by far exceed the rates of dust production by stellar sources as expected from simple evolution models. After the cycle of matter in and out of dust reaches a steady state, the dust growth balances the destruction operating on similar timescales of 350 Myr.<br />17 pages, 11 figures, accepted to ApJ
- Subjects :
- Physics
Extinction
010308 nuclear & particles physics
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
Astrophysics - Astrophysics of Galaxies
Galaxy
13. Climate action
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
0103 physical sciences
Galaxy formation and evolution
Astrophysics::Earth and Planetary Astrophysics
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....80d854d942178105f7035b63d4792e2e