The role of the charge state of PAHs in ultraviolet extinction

Abstract

Aims: We explore the relation between charge state of polycyclic aromatic hydrocarbons (PAHs) and extinction curve morphology. Methods: We fit extinction curves with a dust model including core-mantle spherical particles of mixed chemical composition (silicate core, $s{p}^2$ and $s{p}^3$ carbonaceous layers), and an additional molecular component. We use exact methods to calculate the extinction due to classical particles and accurate computed absorption spectra of PAHs in different charge states, for the contribution due to the molecular component, along a sample of five rather different lines of sight. Results: A combination of classical dust particles and mixtures of real PAHs satisfactorily matches the observed interstellar extinction curves. Variations of the spectral properties of PAHs in different charge states produce changes consistent with the varying relative strengths of the bump and non-linear far-UV rise.

5 pages, 3 figures, Astronomy & Astrophysics Letters, in press

References in corpus (5)

• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• On-line database of the spectral properties of polycyclic aromatic hydrocarbons
• Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium
• Spectropolarimetry of the 3.4 micron Feature in the Diffuse ISM toward the Galactic Center Quintuplet Cluster
• Theoretical evaluation of PAH dications properties

Cited by in corpus (9)

• Electronic spectroscopy of medium-sized polycyclic aromatic hydrocarbons: Implications for the carriers of the 2175 Å UV bump
• Dehydrogenated polycyclic aromatic hydrocarbons and UV bump
• Revealing the dust attenuation properties on resolved scales in NGC628 with SWIFT UVOT data
• Diffuse Interstellar Bands and the Ultraviolet Extinction Curves: The Missing Link Revisited
• Interstellar Silicon Depletion and the Ultraviolet Extinction
• Machine-learning identified molecular fragments responsible for infrared emission features of polycyclic aromatic hydrocarbons
• What causes the ultraviolet extinction bump at the cosmic dawn?
• Analytic formulas for frequency and size dependence of absorption and scattering efficiencies of astronomical polycyclic aromatic hydrocarbons
• Spitzer's perspective of polycyclic aromatic hydrocarbons in galaxies