The Resolved Behavior of Dust Mass, Polycyclic Aromatic Hydrocarbon Fraction, and Radiation Field in ∼800 Nearby Galaxies

Abstract

We present resolved 3.6–250 μ m dust spectral energy distribution (SED) fitting for ∼800 nearby galaxies. We measure the distribution of radiation field intensities heating the dust, the dust mass surface density (Σ _d ), and the fraction of dust in the form of polycyclic aromatic hydrocarbons (PAHs; q _PAH ). We find that the average interstellar radiation field ( $\overline{U}$ ) is correlated both with stellar mass surface density (Σ _⋆ ) and star formation rate surface density (Σ _SFR ), while more intense radiation fields are only correlated with Σ _SFR . We show that q _PAH is a steeply decreasing function of Σ _SFR , likely reflecting PAH destruction in H ii regions. Galaxy-integrated q _PAH is strongly, negatively correlated with specific star formation rate (sSFR) and offset from the star-forming “main sequence” (ΔMS), suggesting that both metallicity and star formation intensity play a role in setting the global q _PAH . We also find a nearly constant M _d / M _* ratio for galaxies on the main sequence, with a lower ratio for more quiescent galaxies, likely due to their lower gas fractions. From these results, we construct prescriptions to estimate the radiation field distribution in both integrated and resolved galaxies. We test these prescriptions by comparing our predicted $\overline{U}$ to results of SED fitting for stacked “main-sequence” galaxies at 0 < z < 4 from M. Béthermin et al. and find sSFR is an accurate predictor of $\overline{U}$ even at these high redshifts. Finally, we describe the public delivery of matched-resolution Wide-field Infrared Survey Explorer and Herschel maps along with the resolved dust SED-fitting results through the Infrared Science Archive.

Keywords

• Interstellar dust
• Polycyclic aromatic hydrocarbons
• Infrared photometry