MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies

D. A. Dale, J. D T Smith, L. Armus, B. A. Buckalew, G. Helou, R. C. Kennicutt, J. Moustakas, H. Roussel, K. Sheth, G. J. Bendo, D. Calzetti, B. T. Draine, C. W. Engelbracht, K. D. Gordon, D. J. Hollenbach, T. H. Jarrett, L. J. Kewley, C. Leitherer, A. Li, S. MalhotraE. J. Murphy, F. Walter

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from ISO and Spitzer, The SINGS data set includes low- and high-resolution spectral maps and broadband imaging in the infrared for over 160 nuclear and extranuclear regions within 75 nearby galaxies spanning a wide range of morphologies, metallicities, luminosities, and star formation rates. Our main result is that these mid-infrared diagnostics effectively constrain a target's dominant power source. The combination of a highionization line index and PAH strength serves as an efficient discriminant between AGNs and star-forming nuclei, confirming progress made with ISO spectroscopy on starbursting and ultraluminous infrared galaxies. The sensitivity of Spitzer allows us to probe fainter nuclear and star-forming regions within galaxy disks. We find that both star-forming nuclei and extranuclear regions stand apart from nuclei that are powered by Seyfert or LINER activity. In fact, we identify areas within four diagnostic diagrams containing >90% Seyfert/LINER nuclei or >90% H II regions/H II nuclei. We also find that, compared to starbursting nuclei, extranuclear regions typically separate even further from AGNs, especially for low-metallicity extranuclear environments. In addition, instead of the traditional midinfrared approach to differentiating between AGNs and star-forming sources that utilizes relatively weak highionization lines, we show that strong low-ionization cooling lines of X-ray-dominated regions like [Si II] 34.82 μm can alternatively be used as excellent discriminants. Finally, the typical target in this sample shows relatively modest interstellar electron density (∼400 cm-3) and obscuration (AV ∼ 1.0 mag for a foreground screen), consistent with a lack of dense clumps of highly obscured gas and dust residing in the emitting regions.

Original languageEnglish (US)
Pages (from-to)161-173
Number of pages13
JournalAstrophysical Journal
Volume646
Issue numberI
DOIs
StatePublished - Jul 20 2006

Fingerprint

galaxies
nuclei
stars
metallicity
disk galaxies
H II regions
occultation
polycyclic aromatic hydrocarbons
clumps
star formation rate
spectral resolution
electron density
dust
diagrams
luminosity
PAH
ionization
broadband
cooling
diagram

Keywords

  • Galaxies: active
  • Galaxies: nuclei - H ii regions
  • Infrared: galaxies
  • Infrared: ISM

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Dale, D. A., Smith, J. D. T., Armus, L., Buckalew, B. A., Helou, G., Kennicutt, R. C., ... Walter, F. (2006). MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies. Astrophysical Journal, 646(I), 161-173. https://doi.org/10.1086/504835

MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies. / Dale, D. A.; Smith, J. D T; Armus, L.; Buckalew, B. A.; Helou, G.; Kennicutt, R. C.; Moustakas, J.; Roussel, H.; Sheth, K.; Bendo, G. J.; Calzetti, D.; Draine, B. T.; Engelbracht, C. W.; Gordon, K. D.; Hollenbach, D. J.; Jarrett, T. H.; Kewley, L. J.; Leitherer, C.; Li, A.; Malhotra, S.; Murphy, E. J.; Walter, F.

In: Astrophysical Journal, Vol. 646, No. I, 20.07.2006, p. 161-173.

Research output: Contribution to journalArticle

Dale, DA, Smith, JDT, Armus, L, Buckalew, BA, Helou, G, Kennicutt, RC, Moustakas, J, Roussel, H, Sheth, K, Bendo, GJ, Calzetti, D, Draine, BT, Engelbracht, CW, Gordon, KD, Hollenbach, DJ, Jarrett, TH, Kewley, LJ, Leitherer, C, Li, A, Malhotra, S, Murphy, EJ & Walter, F 2006, 'MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies', Astrophysical Journal, vol. 646, no. I, pp. 161-173. https://doi.org/10.1086/504835
Dale DA, Smith JDT, Armus L, Buckalew BA, Helou G, Kennicutt RC et al. MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies. Astrophysical Journal. 2006 Jul 20;646(I):161-173. https://doi.org/10.1086/504835
Dale, D. A. ; Smith, J. D T ; Armus, L. ; Buckalew, B. A. ; Helou, G. ; Kennicutt, R. C. ; Moustakas, J. ; Roussel, H. ; Sheth, K. ; Bendo, G. J. ; Calzetti, D. ; Draine, B. T. ; Engelbracht, C. W. ; Gordon, K. D. ; Hollenbach, D. J. ; Jarrett, T. H. ; Kewley, L. J. ; Leitherer, C. ; Li, A. ; Malhotra, S. ; Murphy, E. J. ; Walter, F. / MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies. In: Astrophysical Journal. 2006 ; Vol. 646, No. I. pp. 161-173.
@article{d256d04c15ea4d0eb6db4b7ff30fa67d,
title = "MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies",
abstract = "Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from ISO and Spitzer, The SINGS data set includes low- and high-resolution spectral maps and broadband imaging in the infrared for over 160 nuclear and extranuclear regions within 75 nearby galaxies spanning a wide range of morphologies, metallicities, luminosities, and star formation rates. Our main result is that these mid-infrared diagnostics effectively constrain a target's dominant power source. The combination of a highionization line index and PAH strength serves as an efficient discriminant between AGNs and star-forming nuclei, confirming progress made with ISO spectroscopy on starbursting and ultraluminous infrared galaxies. The sensitivity of Spitzer allows us to probe fainter nuclear and star-forming regions within galaxy disks. We find that both star-forming nuclei and extranuclear regions stand apart from nuclei that are powered by Seyfert or LINER activity. In fact, we identify areas within four diagnostic diagrams containing >90{\%} Seyfert/LINER nuclei or >90{\%} H II regions/H II nuclei. We also find that, compared to starbursting nuclei, extranuclear regions typically separate even further from AGNs, especially for low-metallicity extranuclear environments. In addition, instead of the traditional midinfrared approach to differentiating between AGNs and star-forming sources that utilizes relatively weak highionization lines, we show that strong low-ionization cooling lines of X-ray-dominated regions like [Si II] 34.82 μm can alternatively be used as excellent discriminants. Finally, the typical target in this sample shows relatively modest interstellar electron density (∼400 cm-3) and obscuration (AV ∼ 1.0 mag for a foreground screen), consistent with a lack of dense clumps of highly obscured gas and dust residing in the emitting regions.",
keywords = "Galaxies: active, Galaxies: nuclei - H ii regions, Infrared: galaxies, Infrared: ISM",
author = "Dale, {D. A.} and Smith, {J. D T} and L. Armus and Buckalew, {B. A.} and G. Helou and Kennicutt, {R. C.} and J. Moustakas and H. Roussel and K. Sheth and Bendo, {G. J.} and D. Calzetti and Draine, {B. T.} and Engelbracht, {C. W.} and Gordon, {K. D.} and Hollenbach, {D. J.} and Jarrett, {T. H.} and Kewley, {L. J.} and C. Leitherer and A. Li and S. Malhotra and Murphy, {E. J.} and F. Walter",
year = "2006",
month = "7",
day = "20",
doi = "10.1086/504835",
language = "English (US)",
volume = "646",
pages = "161--173",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "I",

}

TY - JOUR

T1 - MID-infrared spectral diagnostics of nuclear and extranuclear regions in nearby galaxies

AU - Dale, D. A.

AU - Smith, J. D T

AU - Armus, L.

AU - Buckalew, B. A.

AU - Helou, G.

AU - Kennicutt, R. C.

AU - Moustakas, J.

AU - Roussel, H.

AU - Sheth, K.

AU - Bendo, G. J.

AU - Calzetti, D.

AU - Draine, B. T.

AU - Engelbracht, C. W.

AU - Gordon, K. D.

AU - Hollenbach, D. J.

AU - Jarrett, T. H.

AU - Kewley, L. J.

AU - Leitherer, C.

AU - Li, A.

AU - Malhotra, S.

AU - Murphy, E. J.

AU - Walter, F.

PY - 2006/7/20

Y1 - 2006/7/20

N2 - Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from ISO and Spitzer, The SINGS data set includes low- and high-resolution spectral maps and broadband imaging in the infrared for over 160 nuclear and extranuclear regions within 75 nearby galaxies spanning a wide range of morphologies, metallicities, luminosities, and star formation rates. Our main result is that these mid-infrared diagnostics effectively constrain a target's dominant power source. The combination of a highionization line index and PAH strength serves as an efficient discriminant between AGNs and star-forming nuclei, confirming progress made with ISO spectroscopy on starbursting and ultraluminous infrared galaxies. The sensitivity of Spitzer allows us to probe fainter nuclear and star-forming regions within galaxy disks. We find that both star-forming nuclei and extranuclear regions stand apart from nuclei that are powered by Seyfert or LINER activity. In fact, we identify areas within four diagnostic diagrams containing >90% Seyfert/LINER nuclei or >90% H II regions/H II nuclei. We also find that, compared to starbursting nuclei, extranuclear regions typically separate even further from AGNs, especially for low-metallicity extranuclear environments. In addition, instead of the traditional midinfrared approach to differentiating between AGNs and star-forming sources that utilizes relatively weak highionization lines, we show that strong low-ionization cooling lines of X-ray-dominated regions like [Si II] 34.82 μm can alternatively be used as excellent discriminants. Finally, the typical target in this sample shows relatively modest interstellar electron density (∼400 cm-3) and obscuration (AV ∼ 1.0 mag for a foreground screen), consistent with a lack of dense clumps of highly obscured gas and dust residing in the emitting regions.

AB - Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from ISO and Spitzer, The SINGS data set includes low- and high-resolution spectral maps and broadband imaging in the infrared for over 160 nuclear and extranuclear regions within 75 nearby galaxies spanning a wide range of morphologies, metallicities, luminosities, and star formation rates. Our main result is that these mid-infrared diagnostics effectively constrain a target's dominant power source. The combination of a highionization line index and PAH strength serves as an efficient discriminant between AGNs and star-forming nuclei, confirming progress made with ISO spectroscopy on starbursting and ultraluminous infrared galaxies. The sensitivity of Spitzer allows us to probe fainter nuclear and star-forming regions within galaxy disks. We find that both star-forming nuclei and extranuclear regions stand apart from nuclei that are powered by Seyfert or LINER activity. In fact, we identify areas within four diagnostic diagrams containing >90% Seyfert/LINER nuclei or >90% H II regions/H II nuclei. We also find that, compared to starbursting nuclei, extranuclear regions typically separate even further from AGNs, especially for low-metallicity extranuclear environments. In addition, instead of the traditional midinfrared approach to differentiating between AGNs and star-forming sources that utilizes relatively weak highionization lines, we show that strong low-ionization cooling lines of X-ray-dominated regions like [Si II] 34.82 μm can alternatively be used as excellent discriminants. Finally, the typical target in this sample shows relatively modest interstellar electron density (∼400 cm-3) and obscuration (AV ∼ 1.0 mag for a foreground screen), consistent with a lack of dense clumps of highly obscured gas and dust residing in the emitting regions.

KW - Galaxies: active

KW - Galaxies: nuclei - H ii regions

KW - Infrared: galaxies

KW - Infrared: ISM

UR - http://www.scopus.com/inward/record.url?scp=33747511781&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33747511781&partnerID=8YFLogxK

U2 - 10.1086/504835

DO - 10.1086/504835

M3 - Article

AN - SCOPUS:33747511781

VL - 646

SP - 161

EP - 173

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - I

ER -