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

@article{citeulike:3711393, 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 [SIII]18.71um/[SIII]33.48um, but the average ratio of the ensemble indicates a typical interstellar electron density of 300-400 cm^{-3} on \~{}23"x15" scales and 500-600 cm^{-3} using \~{}11"x9" apertures, independent of whether the region probed is a star-forming nuclear, a star-forming extranuclear, or an 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 [NeIII]15.56um/[NeII]12.81um, 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 [NeIII]15.56um/[NeII]12.81um ratios. Finally, [FeII]25.99um/[NeII]12.81um versus [SiII]34.82um/[SIII]33.48um also provides an empirical method for discerning AGN from normal star-forming sources. However, similar to [NeIII]15.56um/[NeII]12.81um, these mid-infrared line ratios lose their AGN/star-formation diagnostic powers for very low metallicity star-forming systems with hard radiation fields.}, archivePrefix = {arXiv}, author = {Dale, D. A. and Smith, J. D. T. and Schlawin, E. A. and Armus, L. and Buckalew, B. A. and Cohen, S. A. and Helou, G. and Jarrett, T. H. and Johnson, L. C. and Moustakas, J. and Murphy, E. J. and Roussel, H. and Sheth, K. and Staudaher, S. and Bot, C. and Calzetti, D. and Engelbracht, C. W. and Gordon, K. D. and Hollenbach, D. J. and Kennicutt, R. C. and Malhotra, S.}, citeulike-article-id = {3711393}, citeulike-linkout-0 = {http://arxiv.org/abs/0811.4190}, citeulike-linkout-1 = {http://arxiv.org/pdf/0811.4190}, day = {25}, eprint = {0811.4190}, keywords = {agn, disentanglement, line, ratios, spitzer}, month = {Nov}, posted-at = {2008-11-27 09:34:08}, priority = {4}, title = {The Spitzer Infrared Nearby Galaxies Survey: A High-Resolution Spectroscopy Anthology}, url = {http://arxiv.org/abs/0811.4190}, year = {2008} }

TY - JOUR ID - citeulike:3711393 L3 - citeulike-article-id:3711393 N2 - 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 [SIII]18.71um/[SIII]33.48um, but the average ratio of the ensemble indicates a typical interstellar electron density of 300-400 cm^{-3} on ~23"x15" scales and 500-600 cm^{-3} using ~11"x9" apertures, independent of whether the region probed is a star-forming nuclear, a star-forming extranuclear, or an 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 [NeIII]15.56um/[NeII]12.81um, 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 [NeIII]15.56um/[NeII]12.81um ratios. Finally, [FeII]25.99um/[NeII]12.81um versus [SiII]34.82um/[SIII]33.48um also provides an empirical method for discerning AGN from normal star-forming sources. However, similar to [NeIII]15.56um/[NeII]12.81um, these mid-infrared line ratios lose their AGN/star-formation diagnostic powers for very low metallicity star-forming systems with hard radiation fields. TI - The Spitzer Infrared Nearby Galaxies Survey: A High-Resolution Spectroscopy Anthology KW - agn KW - disentanglement KW - line KW - ratios KW - spitzer AU - Dale, DA AU - Smith, JDT AU - Schlawin, EA AU - Armus, L AU - Buckalew, BA AU - Cohen, SA AU - Helou, G AU - Jarrett, TH AU - Johnson, LC AU - Moustakas, J AU - Murphy, EJ AU - Roussel, H AU - Sheth, K AU - Staudaher, S AU - Bot, C AU - Calzetti, D AU - Engelbracht, CW AU - Gordon, KD AU - Hollenbach, DJ AU - Kennicutt, RC AU - Malhotra, S PY - 2008/Nov/25/ UR - http://arxiv.org/abs/0811.4190 ER -