The Astrodust+PAH Model: A Unified Description of the Extinction, Emission, and Polarization from Dust in the Diffuse Interstellar Medium
Abstract
We present a new model of interstellar dust in which large grains are a single composite material, "astrodust," and nanoparticle-sized grains come in distinct varieties including polycyclic aromatic hydrocarbons (PAHs). We argue that a single-composition model for grains larger than ~0.02 μm most naturally explains the lack of frequency dependence in the far-infrared (FIR) polarization fraction and the characteristic ratio of optical to FIR polarization. We derive a size distribution and alignment function for 1.4:1 oblate astrodust grains that, with PAHs, reproduce the mean wavelength dependence and polarization of Galactic extinction and emission from the diffuse interstellar medium while respecting constraints on solid-phase abundances. All model data and Python-based interfaces are made publicly available.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2023
- DOI:
- 10.3847/1538-4357/acc4c2
- arXiv:
- arXiv:2208.12365
- Bibcode:
- 2023ApJ...948...55H
- Keywords:
-
- Dust composition;
- Dust continuum emission;
- Dust formation;
- Dust physics;
- Astrophysical dust processes;
- Interstellar dust extinction;
- Interstellar dust processes;
- Optical constants (Dust);
- Starlight polarization;
- 2271;
- 412;
- 2269;
- 2229;
- 99;
- 837;
- 838;
- 2270;
- 1571;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 34 pages, 19 figures. Data available at https://dataverse.harvard.edu/dataverse/astrodust