A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies

T. Díaz-Santos, L. Armus, V. Charmandaris, N. Lu, S. Stierwalt, G. Stacey, S. Malhotra, P. P.Van Der Werf, J. H. Howell, G. C. Privon, J. M. Mazzarella, P. F. Goldsmith, E. J. Murphy, L. Barcos-Muñoz, S. T. Linden, H. Inami, K. L. Larson, A. S. Evans, P. Appleton, K. IwasawaS. Lord, D. B. Sanders, J. A. Surace

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

We present an analysis of [O I]63, [O III]88, [N II]122, and [C II]158 far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ∼240 local luminous infrared galaxies (LIRGs) in the Great Observatories Allsky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [N II]122, [O I]63, and [C II]158 as a function of FIR color and infrared luminosity surface density, IR. The median electron density of the ionized gas in LIRGs, based on the [N II]122/[N II]205 ratio, is ne=41 cm-3. We find that the dispersion in the [C II]158 deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [C II]158 emission, f ([C II]158 PDR)=[C II]158 PDR/[C II]158, which increases from ∼60% to ∼95% in the warmest LIRGs. The [O I]63/[C II]158 PDR ratio is tightly correlated with the PDR gas kinetic temperature in sources where [O I]63 is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, nH, and intensity of the interstellar radiation field, G, in units of G0 and find G/nH ratios of ∼0.1-50G0cm3, with ULIRGs populating the upper end of the distribution. There is a relation between G/nH and IR, showing a critical break at IR∗; 5 × 1010 L kpc-2. BelowIR∗, G/nH remains constant, ;0.32G0cm3, and variations inIR are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. AboveIR∗, G/nH increases rapidly withIR, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.

Original languageEnglish (US)
Article number32
JournalAstrophysical Journal
Volume846
Issue number1
DOIs
StatePublished - Sep 1 2017
Externally publishedYes

Fingerprint

photodissociation
galaxies
radiation distribution
interstellar radiation
stars
ionized gases
gas
observatories
electron density
fine structure
luminosity
observatory
continuums
color
hydrogen
geometry
kinetics
gases

Keywords

  • galaxies: evolution
  • galaxies: ISM
  • galaxies: nuclei
  • galaxies: starburst
  • infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Díaz-Santos, T., Armus, L., Charmandaris, V., Lu, N., Stierwalt, S., Stacey, G., ... Surace, J. A. (2017). A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies. Astrophysical Journal, 846(1), [32]. https://doi.org/10.3847/1538-4357/aa81d7

A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies. / Díaz-Santos, T.; Armus, L.; Charmandaris, V.; Lu, N.; Stierwalt, S.; Stacey, G.; Malhotra, S.; Werf, P. P.Van Der; Howell, J. H.; Privon, G. C.; Mazzarella, J. M.; Goldsmith, P. F.; Murphy, E. J.; Barcos-Muñoz, L.; Linden, S. T.; Inami, H.; Larson, K. L.; Evans, A. S.; Appleton, P.; Iwasawa, K.; Lord, S.; Sanders, D. B.; Surace, J. A.

In: Astrophysical Journal, Vol. 846, No. 1, 32, 01.09.2017.

Research output: Contribution to journalArticle

Díaz-Santos, T, Armus, L, Charmandaris, V, Lu, N, Stierwalt, S, Stacey, G, Malhotra, S, Werf, PPVD, Howell, JH, Privon, GC, Mazzarella, JM, Goldsmith, PF, Murphy, EJ, Barcos-Muñoz, L, Linden, ST, Inami, H, Larson, KL, Evans, AS, Appleton, P, Iwasawa, K, Lord, S, Sanders, DB & Surace, JA 2017, 'A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies', Astrophysical Journal, vol. 846, no. 1, 32. https://doi.org/10.3847/1538-4357/aa81d7
Díaz-Santos T, Armus L, Charmandaris V, Lu N, Stierwalt S, Stacey G et al. A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies. Astrophysical Journal. 2017 Sep 1;846(1). 32. https://doi.org/10.3847/1538-4357/aa81d7
Díaz-Santos, T. ; Armus, L. ; Charmandaris, V. ; Lu, N. ; Stierwalt, S. ; Stacey, G. ; Malhotra, S. ; Werf, P. P.Van Der ; Howell, J. H. ; Privon, G. C. ; Mazzarella, J. M. ; Goldsmith, P. F. ; Murphy, E. J. ; Barcos-Muñoz, L. ; Linden, S. T. ; Inami, H. ; Larson, K. L. ; Evans, A. S. ; Appleton, P. ; Iwasawa, K. ; Lord, S. ; Sanders, D. B. ; Surace, J. A. / A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies. In: Astrophysical Journal. 2017 ; Vol. 846, No. 1.
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abstract = "We present an analysis of [O I]63, [O III]88, [N II]122, and [C II]158 far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ∼240 local luminous infrared galaxies (LIRGs) in the Great Observatories Allsky LIRG Survey. We find pronounced declines ({"}deficits{"}) of line-to-FIR continuum emission for [N II]122, [O I]63, and [C II]158 as a function of FIR color and infrared luminosity surface density, IR. The median electron density of the ionized gas in LIRGs, based on the [N II]122/[N II]205 ratio, is ne=41 cm-3. We find that the dispersion in the [C II]158 deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [C II]158 emission, f ([C II]158 PDR)=[C II]158 PDR/[C II]158, which increases from ∼60{\%} to ∼95{\%} in the warmest LIRGs. The [O I]63/[C II]158 PDR ratio is tightly correlated with the PDR gas kinetic temperature in sources where [O I]63 is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, nH, and intensity of the interstellar radiation field, G, in units of G0 and find G/nH ratios of ∼0.1-50G0cm3, with ULIRGs populating the upper end of the distribution. There is a relation between G/nH and IR, showing a critical break at IR∗; 5 × 1010 L kpc-2. BelowIR∗, G/nH remains constant, ;0.32G0cm3, and variations inIR are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. AboveIR∗, G/nH increases rapidly withIR, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.",
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T1 - A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies

AU - Díaz-Santos, T.

AU - Armus, L.

AU - Charmandaris, V.

AU - Lu, N.

AU - Stierwalt, S.

AU - Stacey, G.

AU - Malhotra, S.

AU - Werf, P. P.Van Der

AU - Howell, J. H.

AU - Privon, G. C.

AU - Mazzarella, J. M.

AU - Goldsmith, P. F.

AU - Murphy, E. J.

AU - Barcos-Muñoz, L.

AU - Linden, S. T.

AU - Inami, H.

AU - Larson, K. L.

AU - Evans, A. S.

AU - Appleton, P.

AU - Iwasawa, K.

AU - Lord, S.

AU - Sanders, D. B.

AU - Surace, J. A.

PY - 2017/9/1

Y1 - 2017/9/1

N2 - We present an analysis of [O I]63, [O III]88, [N II]122, and [C II]158 far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ∼240 local luminous infrared galaxies (LIRGs) in the Great Observatories Allsky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [N II]122, [O I]63, and [C II]158 as a function of FIR color and infrared luminosity surface density, IR. The median electron density of the ionized gas in LIRGs, based on the [N II]122/[N II]205 ratio, is ne=41 cm-3. We find that the dispersion in the [C II]158 deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [C II]158 emission, f ([C II]158 PDR)=[C II]158 PDR/[C II]158, which increases from ∼60% to ∼95% in the warmest LIRGs. The [O I]63/[C II]158 PDR ratio is tightly correlated with the PDR gas kinetic temperature in sources where [O I]63 is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, nH, and intensity of the interstellar radiation field, G, in units of G0 and find G/nH ratios of ∼0.1-50G0cm3, with ULIRGs populating the upper end of the distribution. There is a relation between G/nH and IR, showing a critical break at IR∗; 5 × 1010 L kpc-2. BelowIR∗, G/nH remains constant, ;0.32G0cm3, and variations inIR are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. AboveIR∗, G/nH increases rapidly withIR, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.

AB - We present an analysis of [O I]63, [O III]88, [N II]122, and [C II]158 far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ∼240 local luminous infrared galaxies (LIRGs) in the Great Observatories Allsky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [N II]122, [O I]63, and [C II]158 as a function of FIR color and infrared luminosity surface density, IR. The median electron density of the ionized gas in LIRGs, based on the [N II]122/[N II]205 ratio, is ne=41 cm-3. We find that the dispersion in the [C II]158 deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [C II]158 emission, f ([C II]158 PDR)=[C II]158 PDR/[C II]158, which increases from ∼60% to ∼95% in the warmest LIRGs. The [O I]63/[C II]158 PDR ratio is tightly correlated with the PDR gas kinetic temperature in sources where [O I]63 is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, nH, and intensity of the interstellar radiation field, G, in units of G0 and find G/nH ratios of ∼0.1-50G0cm3, with ULIRGs populating the upper end of the distribution. There is a relation between G/nH and IR, showing a critical break at IR∗; 5 × 1010 L kpc-2. BelowIR∗, G/nH remains constant, ;0.32G0cm3, and variations inIR are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. AboveIR∗, G/nH increases rapidly withIR, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.

KW - galaxies: evolution

KW - galaxies: ISM

KW - galaxies: nuclei

KW - galaxies: starburst

KW - infrared: galaxies

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