Probing the Excitation of Extreme Starbursts: High Resolution Mid-IR Spectroscopy of Blue Compact Dwarfs

Abstract

We present an analysis of the mid-infrared emission lines for a sample of 12 low metallicity Blue Compact Dwarf (BCD) galaxies based on high resolution observations obtained with Infrared Spectrograph on board the {\rm Spitzer} Space Telescope. We compare our sample with a local sample of typical starburst galaxies and active galactic nuclei (AGNs), to study the ionization field of starbursts over a broad range of physical parameters and examine its difference from the one produced by AGN. The high-ionization line [OIV]25.89$\mu$m is detected in most of the BCDs, starbursts, and AGNs in our sample. We propose a diagnostic diagram of the line ratios [OIV]25.89$\mu$m/[SIII]33.48$\mu$m as a function of [NeIII]15.56$\mu$m/[NeII]12.81$\mu$m which can be useful in identifying the principal excitation mechanism in a galaxy. Galaxies in this diagram split naturally into two branches. Classic AGNs as well as starburst galaxies with an AGN component populate the upper branch, with stronger AGNs displaying higher [NeIII]/[NeII] ratios. BCDs and pure starbursts are located in the lower branch. We find that overall the placement of galaxies on this diagram correlates well with their corresponding locations in the log([NII]/H$\alpha$) vs. log([OIII]/H$\beta$) diagnostic diagram, which has been widely used in the optical. The two diagrams provide consistent classifications of the excitation mechanism in a galaxy. On the other hand, the diagram of [NeIII]15.56$\mu$m/[NeII]12.81$\mu$m vs. [SIV]10.51$\mu$m/[SIII]18.71$\mu$m is not as efficient in separating AGNs from BCDs and pure starbursts. (abridged)

15 pages, including 1 table and 14 figures. Accepted by ApJ

References in corpus (14)

• The Host Galaxies and Classification of Active Galactic Nuclei
• The MAPPINGS III Library of Fast Radiative Shock Models
• Mid-IR Galaxy Classification Based on Silicate Obscuration and PAH Equivalent Width
• High resolution mid-infrared spectroscopy of ultraluminous infrared galaxies
• The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
• Mid-Infrared Spectral Diagnostics of Nuclear and Extra-Nuclear Regions in Nearby Galaxies
• Chemical composition and mixing in giant HII regions: NGC3603, 30Doradus, and N66
• Spatially Resolved Spitzer Spectroscopy of the Starburst Nucleus in NGC 5253
• Elemental Abundances of Blue Compact Dwarfs from mid-IR Spectroscopy with Spitzer
• The Mid-Infrared [SIV]/[NeII] versus [NeIII]/[NeII] Correlation
• Blue Compact Dwarf Galaxies with Spitzer: The Infrared/Radio Properties
• Tracing the [FeII]/[NeII] ratio and its relationship with other ISM indicators within star forming dwarf galaxies: a Spitzer IRS archival study
• NGC 3310 and Its Tidal Debris: Remnants of Galaxy Evolution
• The Extraordinary Infrared Spectrum of NGC 1222 (Mkn 603)

Cited by in corpus (31)

• The Spitzer View of Low-Metallicity Star Formation: III. Fine Structure Lines, Aromatic Features, and Molecules
• Mid-Infrared Atomic Fine-Structure Emission Line Spectra of Luminous Infrared Galaxies: Spitzer/IRS Spectra of the GOALS Sample
• Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database
• Mid-Infrared Properties of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. I. Emission-Line Diagnostics
• Towards a Complete Census of AGNs in Nearby Galaxies: The Incidence of Growing Black Holes
• GOALS-JWST: Tracing AGN Feedback on the Star-Forming ISM in NGC 7469
• The interstellar medium in high-redshift submillimeter galaxies as probed by infrared spectroscopy
• Probing high-redshift quasars with ALMA. I. Expected observables and potential number of sources
• Physical Properties of II Zw 40's Super Star Cluster and Nebula: New Insights and Puzzles from UV Spectroscopy
• Dust emission in star-forming dwarf galaxies: General properties and the nature of the sub-mm excess
• Ultra-Luminous X-ray Sources in Haro 11 and the Role of X-ray Binaries in Feedback in Lyman-alpha Emitting Galaxies
• Infrared Spectroscopy of Halos of Edge-on Galaxies
• A Framework for Modeling Polycyclic Aromatic Hydrocarbon Emission in Galaxy Evolution Simulations
• Theoretical Modeling of Emission-Line galaxies: New Classification Parameters for Mid-Infrared and Optical Spectroscopy
• The first Infrared study of the close environment of a long Gamma-Ray Burst
• Optical and JWST Mid-IR Emission Line Diagnostics for Simultaneous IMBH and Stellar Excitation in z~0 Dwarf Galaxies
• Spitzer IRS Spectral Mapping of the Toomre Sequence: Spatial Variations of PAH, Gas, and Dust Properties in Nearby Major Mergers
• A New Technique for Measuring Polycyclic Aromatic Hydrocarbon Emission in Different Environments
• Mid-Infrared Spectroscopy of Two Lensed Star-forming Galaxies
• A New Radio Loudness Diagnostic for Active Galaxies: a Radio-To-Mid-Infrared Parameter
• Dissecting the Mid-Infrared Heart of M83 with JWST
• The Diagnostics and Possible Evolution in Active Galactic Nuclei Associated With Starburst Galaxies
• Exploring the relationship between black hole accretion and star formation with blind mid-/far-infrared spectroscopic surveys
• Exploring the mysterious high-ionization source powering [Ne V] in high-z analog SBS0335-052 E with JWST/MIRI
• Searching for an Intermediate Mass Black Hole in the Blue Compact Dwarf galaxy MRK 996
• Core Revelations: the Star Formation and AGN Connection at the Heart of NGC 7469
• The Curious Case of Glass I: High Ionization and Variability of Different Types
• On the origin of X-ray oxygen emission-lines in obscured AGN
• MIRACLE II: Unveiling the multi-phase gas interplay in the circumnuclear region of NGC 1365 via multi-cloud modeling
• Infrared view of the multiphase ISM in NGC 253 II. Modelling the ionised and neutral atomic gas
• Mid-IR properties of Seyferts: Spitzer/IRS spectroscopy of the IRAS 12micron Seyfert sample