NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-24 T13:13:52 PDT
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For refcode 2009ApJ...693.1821D:
Retrieve 163 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
2009ApJ...693.1821D The Spitzer Infrared Nearby Galaxies Survey: A High-Resolution Spectroscopy Anthology Dale, D. A.; Smith, J. D. T.; Schlawin, E. A.; Armus, L.; Buckalew, B. A.; Cohen, S. A.; Helou, G.; Jarrett, T. H.; Johnson, L. C.; Moustakas, J.; Murphy, E. J.; Roussel, H.; Sheth, K.; Staudaher, S.; Bot, C.; Calzetti, D.; Engelbracht, C. W.; Gordon, K. D.; Hollenbach, D. J.; Kennicutt, R. C.; Malhotra, S. Abstract. High-resolution mid-infrared spectra are presented for 155 nuclear and extranuclear regions from the Spitzer Infrared Nearby Galaxies Survey (SINGS). The fluxes for nine atomic forbidden and three molecular hydrogen mid-infrared emission lines are also provided, along with upper limits in key lines for infrared-faint targets. The SINGS sample shows a wide range in the ratio of [S III] 18.71 micron/[S III] 33.48 micron, but the average ratio of the ensemble indicates a typical interstellar electron density of 300-400 cm^-3^ on ~23" x 15" scales and 500-600 cm^-3^ using ~11" x 9" apertures, independent of whether the region probed is a star-forming nuclear, a star-forming extranuclear, or an active galactic nuclei (AGN) environment. Evidence is provided that variations in gas-phase metallicity play an important role in driving variations in radiation field hardness, as indicated by [Ne III] 15.56 micron/[Ne II] 12.81 micron, for regions powered by star formation. Conversely, the radiation hardness for galaxy nuclei powered by accretion around a massive black hole is independent of metal abundance. Furthermore, for metal-rich environments AGN are distinguishable from star-forming regions by significantly larger [Ne III] 15.56 micron/[Ne II] 12.81 micron ratios. Finally, [Fe II] 25.99 micron/[Ne II] 12.81 micron versus [Si II] 34.82 micron/[S III] 33.48 micron also provides an empirical method for discerning AGN from normal star-forming sources. However, similar to [Ne III] 15.56 micron/[Ne II] 12.81 micron, these mid-infrared line ratios lose their AGN/star-formation diagnostic powers for very low metallicity star-forming systems with hard radiation fields. Key words: accretion, accretion disks, galaxies: active, galaxies: jets
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