The Dielectric Function of "Astrodust" and Predictions for Polarization in the 3.4$\mu$m and 10$\mu$m Features

Abstract

The dielectric function of interstellar dust material is modeled using observations of extinction and polarization in the infrared, together with estimates for the mass of interstellar dust. The "astrodust" material is assumed to be a mix of amorphous silicates and other materials, including hydrocarbons producing an absorption feature at 3.4$\mu$m. The detailed shape of the 10$\mu$m polarization profile depends on the assumed porosity and grain shape, but the 10$\mu$m spectropolarimetric data are not yet good enough to clearly favor one shape over another, nor to constrain the porosity. The expected 3.4$\mu$m feature polarization is consistent with existing upper limits, provided the 3.4$\mu$m absorption is preferentially located in grain surface layers; a separate population of non-aligned carbonaceous grains is not required. We predict the 3.4$\mu$m polarization feature to be $(\Delta p{)}_{3.4\mu \mathrm{m}}/p(10\mu \mathrm{m})\approx 0.016$, just below current upper limits. Polarization by the same grains at submm wavelengths is also calculated.

32 pages, 10 figures. Submitted to Ap.J

References in corpus (15)

• 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
• Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
• The shape and composition of interstellar silicate grains
• Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization
• The Efficiency of Grain Alignment in Dense Interstellar Clouds: A Reassessment of Constraints from Near Infrared Polarization
• A new, large-scale map of interstellar reddening derived from HI emission
• Observational Constraints on the Physical Properties of Interstellar Dust in the Post-Planck Era
• Spectropolarimetry of the 3.4 micron Feature in the Diffuse ISM toward the Galactic Center Quintuplet Cluster
• The infrared emission spectra of compositionally inhomogeneous aggregates composed of irregularly shaped constituents
• The Composition of Interstellar Grains Toward Zeta Ophiuchi: Constraining the Elemental Budget Near the Diffuse-Dense Cloud Transition
• Silicate Composition of the Interstellar Medium
• Spectropolarimetric Constraints on the Nature of Interstellar Grains
• Constraints on interstellar dust models from extinction and spectro-polarimetry

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