Tracing the [FeII]/[NeII] ratio and its relationship with other ISM indicators within star forming dwarf galaxies: a Spitzer IRS archival study

Abstract

Archival Spitzer observations of 41 starburst galaxies that span a wide range in metallicity reveal for the first time a correlation between the [FeII]/[NeII] 26.0/12.8 micron ratio and the electron gas density as traced by the 18.7/33.4 micron [SIII] ratio, with the [FeII]/[NeII] ratio decreasing with increasing gas density. The correlations of the [FeII]/[NeII] ratio, the PAH peak to continuum strength & metallicity found in an earlier paper were confirmed for a larger sample. We also find a strong correlation between the gas density and the PAH peak to continuum strength. Using shock and photoionization models, we see the driver of the observed [FeII]/[NeII] ratios is metallicity. The majority of [FeII] emission in low metallicity galaxies may be shock-derived, whilst at high metallicity, the [FeII] emission may be instead dominated by contributions from HII and in particular from dense PDR regions. However, the observed [FeII]/[NeII] ratios may instead be following a metallicity-abundance relationship, with iron being less depleted onto grains in low metallicity galaxies - a result that would have profound implications for the use of iron emission lines as unambiguous tracers of shocks.

11 pages, 7 figures, preprint produced in ApJ format using emulateapj. Accepted for publication in ApJ

References in corpus (33)

• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• Theoretical Modeling of Starburst Galaxies
• Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
• Interstellar Dust Grains
• A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
• Using Strong Lines to Estimate Abundances in Extragalactic HII Regions and Starburst Galaxies
• The chemical composition of metal-poor emission-line galaxies in the Data Release 3 of the Sloan Digital Sky Survey
• The SMART Data Analysis Package for the Infrared Spectrograph on the Spitzer Space Telescope
• Starburst-driven galactic winds: I. Energetics and intrinsic X-ray emission
• A large mid-infrared spectroscopic and near-IR imaging survey of ULIRGs: their nature and evolution
• A Spitzer Space Telescope Infrared Survey of Supernova Remnants in the Inner Galaxy
• Mid Infrared Properties of Low Metallicity Blue Compact Dwarf Galaxies From Spitzer/IRS
• Stellar Evolutionary Effects on the Abundances of PAH and SN-Condensed Dust in Galaxies
• Molecular hydrogen formation in the interstellar medium
• Mid-infrared and optical spectroscopy of ultraluminous infrared galaxies: A comparison
• Warm dust and aromatic bands as quantitative probes of star-formation activity
• The H II Region/PDR Connection: Self-Consistent Calculations of Physical Conditions in Star-Forming Regions
• A mid-infrared spectroscopic survey of starburst galaxies: excitation and abundances
• Molecular Hydrogen in Star-forming regions: implementation of its micro-physics in Cloudy
• High-Resolution X-ray Spectroscopy of the Interstellar Medium II: Neon and Iron Absorption Edges
• The PAH Emission Deficit In Low-Metallicity Galaxies - A Spitzer View
• Grain size distributions and photo-electric heating in ionized media
• The [Fe IV] Discrepancy: Constraining the Iron Abundances in Nebulae
• The Ionized Gas in Local Starburst Galaxies: Global and Small--Scale Feedback from Star Formation
• Mid-Infrared Fine Structure Line Ratios in Active Galactic Nuclei Observed with Spitzer IRS: Evidence for Extinction by the Torus
• Spitzer-IRS Spectroscopy of the Prototypical Starburst Galaxy NGC7714
• Infrared Spectroscopy of Molecular Supernova Remnants
• Deep VLT spectroscopy of the blue compact dwarf galaxies Tol 1214-277 and Tol 65
• A Chandra X-ray survey of nearby dwarf starburst galaxies: I. Data reduction and results
• Chandra X-Ray Imaging of the Interacting Starburst Galaxy System NGC 7714/5: Tidal ULXs, Emergent Wind, and Resolved HII Regions
• The impact on the general properties of HII galaxies in the local universe of the visibility of the [OIII]l 4363 line
• Chandra Detection of Fe XVII in Absorption: Iron Abundance in the Hot Gaseous Interstellar Medium

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• Probing the Dust Properties of Galaxies up to Submillimetre Wavelengths I. The Spectral Energy Distribution of dwarf galaxies using LABOCA
• Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database
• The nature of the interstellar medium of the starburst low-metallicity galaxy Haro11: a multi-phase model of the infrared emission
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