Interstellar Dust Models and Evolutionary Implications

TL;DR

This paper presents a comprehensive model of interstellar dust that aligns with observations, emphasizing the importance of in-ISM grain growth and the processes shaping dust composition, structure, and size distribution.

Contribution

The paper introduces a dust model consistent with observations, highlighting the dominant role of in-ISM grain growth over stellar sources in dust formation.

Findings

The model reproduces observed extinction and polarization.

Most interstellar dust material is grown in the ISM.

Dust in high-redshift systems is primarily produced in the ISM.

Abstract

The wavelength dependences of interstellar extinction and polarization, supplemented by observed elemental abundances and the spectrum of infrared emission from dust heated by starlight, strongly constrain dust models. One dust model that appears to be consistent with observations is presented. To reproduce the observed extinction, the model consumes the bulk of interstellar Mg, Si, and Fe (in amorphous silicates), and a substantial fraction of C (in carbonaceous material), with size distributions and alignment adjusted to match observations. The composition, structure, and size distribution of interstellar grains is the result of injection of dust from stellar outflows into the interstellar medium (ISM), followed by destruction, growth, coagulation, and photoprocessing of interstellar grains. The balance among these poorly-understood processes is responsible for the mix of solid material present in the ISM. Most interstellar grain material present in the diffuse ISM must be grown in the ISM. The amorphous silicate and carbonaceous materials that form the bulk of interstellar dust must therefore be the result of grain growth in the presence of ultraviolet radiation. Dust in high-z systems such as J1148+5251 is also produced primarily in the ISM, with supernova-produced dust contributing only a small fraction of the total dust mass.