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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1821-1834 |
| Number of pages | 14 |
| Journal | Astrophysical Journal |
| Volume | 693 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 10 2009 |
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Keywords
- accretion, accretion
- disks
- galaxies: active
- galaxies: jets
ASJC Scopus subject areas
- Space and Planetary Science
- Astronomy and Astrophysics
Cite this
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.
In: Astrophysical Journal, Vol. 693, No. 2, 10.03.2009, p. 1821-1834.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The spitzer infrared nearby galaxies survey
T2 - A high-resolution spectroscopy anthology
AU - Dale, D. A.
AU - Smith, J. D T
AU - Schlawin, E. A.
AU - Armus, L.
AU - Buckalew, B. A.
AU - Cohen, S. A.
AU - Helou, G.
AU - Jarrett, T. H.
AU - Johnson, L. C.
AU - Moustakas, J.
AU - Murphy, E. J.
AU - Roussel, H.
AU - Sheth, K.
AU - Staudaher, S.
AU - Bot, C.
AU - Calzetti, D.
AU - Engelbracht, C. W.
AU - Gordon, K. D.
AU - Hollenbach, D. J.
AU - Kennicutt, R. C.
AU - Malhotra, S.
PY - 2009/3/10
Y1 - 2009/3/10
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 [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.
AB - 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.
KW - accretion, accretion
KW - disks
KW - galaxies: active
KW - galaxies: jets
UR - http://www.scopus.com/inward/record.url?scp=66649094313&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=66649094313&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/693/2/1821
DO - 10.1088/0004-637X/693/2/1821
M3 - Article
AN - SCOPUS:66649094313
VL - 693
SP - 1821
EP - 1834
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
ER -