The Spitzer Infrared Nearby Galaxies Survey: A High-Resolution Spectroscopy Anthology

March 2009 • 2009ApJ...693.1821D

Authors • 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 μm/[S III] 33.48 μm, but the average ratio of the ensemble indicates a typical interstellar electron density of 300-400 cm^-3 on ~23'' × 15'' scales and 500-600 cm^-3 using ~11'' × 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 μm/[Ne II] 12.81 μm, 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 μm/[Ne II] 12.81 μm ratios. Finally, [Fe II] 25.99 μm/[Ne II] 12.81 μm versus [Si II] 34.82 μm/[S III] 33.48 μm also provides an empirical method for discerning AGN from normal star-forming sources. However, similar to [Ne III] 15.56 μm/[Ne II] 12.81 μm, these mid-infrared line ratios lose their AGN/star-formation diagnostic powers for very low metallicity star-forming systems with hard radiation fields.

Links

• PREPRINT http://arxiv.org/abs/0811.4190
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2009ApJ...693.1821D
• ELECTR https://doi.org/10.1088%2F0004-637X%2F693%2F2%2F1821
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2009ApJ...693.1821D
• PDF https://iopscience.iop.org/article/10.1088/0004-637X/693/2/1821/pdf
• PDF https://stacks.iop.org/0004-637X/693/1821/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/693/1821
• DATA https://irsa.ipac.caltech.edu/bibdata/2009/D/2009ApJ...693.1821D.html
• SPIRES http://inspirehep.net/search?p=find+eprint+arXiv:0811.4190