Polycyclic Aromatic Hydrocarbon emission in Spitzer/IRS maps I: Catalog and simple diagnostics

Abstract

We present a sample of resolved galactic HII regions and photodissociation regions (PDRs) observed with the Spitzer infrared spectrograph (IRS) in spectral mapping mode between the wavelengths of 5--15 $\mu$m. For each object we have spectral maps at a spatial resolution of $\sim$4" in which we have measured all of the mid-infrared emission and absorption features. These include the PAH emission bands, primarily at 6.2, 7.7, 8.6, 11.2 and 12.7 $\mu$m, as well as the spectral emission lines of neon and sulfur and the absorption band caused by silicate dust at around 9.8 $\mu$m. In this work we describe the data in detail, including the data reduction and measurement strategies, and subsequently present the PAH emission band intensity correlations for each of the objects and the sample as a whole. We find that there are distinct differences between the sources in the sample, with two main groups, the first comprising the HII regions and the second the reflection nebulae (RNe). Three sources, the reflection nebula NGC~7023, the Horsehead nebula PDR (an interface between the HII region IC~434 and the Orion B molecular cloud) and M 17, resist this categorization, with the Horsehead PDR points mimicking the RNe and the NGC~7023 fluxes displaying unique bifurcated appearance in our correlation plots. These discrepancies seem to be due to the very low radiation field experienced by the Horsehead PDR and the very clean separation between the PDR environment and a diffuse environment in the NGC~7023 observations.

17 pages, 9 figures. ApJ accepted

References in corpus (11)

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• Variations of the Mid-IR Aromatic Features Inside and Among Galaxies
• Spectral Mapping Reconstruction of Extended Sources
• Main-Seqence Fitting Distance to the sigma Ori Cluster
• Dust processing in photodissociation regions - Mid-IR emission modelling
• Blowing in the wind: The dust wave surrounding $\sigma$ Ori AB
• Polycyclic Aromatic Hydrocarbons with armchair edges and the 12.7 μm band
• Probing the Ionization States of Polycyclic Aromatic Hydrocarbons via the 15-20 μm Emission Bands
• The mid-infrared appearance of the Galactic Mini-Starburst W49A
• A bimodal dust grain distribution in the IC 434 HII region
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• Polycyclic Aromatic Hydrocarbon emission in Spitzer/IRS maps II: A direct link between band profiles and the radiation field strength
• Interpreting the subtle spectral variations of the 11.2 and 12.7 μm polycyclic aromatic hydrocarbon bands
• A Principal Component Analysis of polycyclic aromatic hydrocarbon emission in NGC 2023
• Polycyclic Aromatic Hydrocarbon emission model in photodissociation regions I: Application to the 3.3, 6.2, and 11.2 $\mu$m bands
• Spectral variations among different scenarios of PAH processing or formation
• Polycyclic Aromatic Hydrocarbon Size Tracers
• The 3.3 $\mu$m Infrared Emission Feature: Observational and Laboratory Constraints on Its Carrier
• High-resolution images of two wiggling stellar jets, MHO 1502 and MHO 2147, obtained with GSAOI+GeMS
• A Principal Component Analysis of polycyclic aromatic hydrocarbon emission in NGC 7023
• Characterizing Spatial Variations of PAH Emission in the Reflection Nebula NGC 1333
• Polycyclic aromatic hydrocarbon emission toward the Galactic bulge
• Spatial variations of PAH properties in M17SW revealed by Spitzer/IRS spectral mapping
• 3D structure of HII regions in the star-forming complex S254-S258
• PDRs4All: XVIII. The evolution of the PAH ionisation and PAH size distribution across the Orion Bar
• Tracing PAH Size in Prominent Nearby Mid-Infrared Environments
• SPHEREx: Aromatics, Aliphatics and PAH Size across the Iris Nebula
• JWST observations of photodissociation regions. IV. Carbonaceous emission band sub-components in NGC 7023 have distinct spatial distributions
• Characterizing the PAH Emission in the Orion Bar