Dust-depletion sequences in damped Ly-α absorbers II. The composition of cosmic dust, from low-metallicity systems to the Galaxy

Abstract

We aim at assessing what are the most dominant dust species or types, including silicate and iron oxide grains present in the ISM, by using recent observations of dust depletion of galaxies at various evolutionary stages. We use the observed elemental abundances in dust of several metals (O, S, Si, Mg, and Fe) in different environments, considering systems with different metallicities and dust content, namely damped Lyman-α absorbers (DLAs) towards quasars and the Galaxy. We derive a possible dust composition by computationally finding the statistically expected elemental abundances in dust assuming a set of key dust species with the iron content as a free parameter. Carbonaceous dust is not considered in the present study. Metallic iron (likely in the form of inclusions in silicate grains) and iron oxides is an important component of the mass composition of carbon-free dust. Iron oxides make up a significant mass fraction (~1/4 in some cases) of the oxygen-bearing dust and there are good reasons to believe that metallic iron constitutes a similar mass fraction of dust. Wüstite (FeO) could be a simple explanation for the depletion of iron and oxygen because it is easily formed. There appears to be no silicate species clearly dominating the silicate mass, but rather a mix of iron-poor as well as iron-rich olivine and pyroxene. To what extent sulphur depletion is due to sulfides remains unclear. In general, there seems to be little evolution of the dust composition (not considering carbonaceous dust) from low-metallicity systems to the Galaxy.

12 pages, 6 figures. Accepted for publication in Astronomy & Astrophysics. Updated to match version to appear online as a forthcoming paper

References in corpus (8)

• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point
• The shape and composition of interstellar silicate grains
• A close halo of large transparent grains around extreme red giant stars
• Exploring wind-driving dust species in cool luminous giants I. Basic criteria and dynamical models of M-type AGB stars
• The Herschel exploitation of local galaxy Andromeda (HELGA) V: Strengthening the case for substantial interstellar grain growth
• The Composition of Interstellar Grains Toward Zeta Ophiuchi: Constraining the Elemental Budget Near the Diffuse-Dense Cloud Transition

Cited by in corpus (10)

• Dust depletion of metals from local to distant galaxies I: Peculiar nucleosynthesis effects and grain growth in the ISM
• Magnesium and silicon in interstellar dust: an X-ray overview
• Dust depletion of of metals from local to distant galaxies II: Cosmic dust-to-metal ratio and dust composition
• Galactic dust evolution with rapid dust formation in the interstellar medium due to hypersonic turbulence
• On the grain-size distribution of turbulent dust growth
• Inhibited destruction of dust by supernova in a clumpy medium
• Three-component modelling of O-rich AGB star winds I. Effects of drift using forsterite
• The optical constants and grain sizes of interstellar dust measured directly using the dust scattered x-ray halo of GRB 221009A
• Acceleration and clustering of cosmic dust in a gravoturbulent gas -- I. Numerical simulation of the nearly Jeans-unstable case
• Observed cosmic evolution of galaxy dust properties with metallicity and tensions with models