A Herschel/PACS Far-infrared Line Emission Survey of Local Luminous Infrared Galaxies
By T. Díaz-Santos, Lee Armus, Vassilis Charmandaris, N. Lu, S. Stierwalt, G. Stacey, S. Malhotra, P. Werf, J. Howell, G. Privon and 13 more. 2017
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We present an analysis of , [O iii]88, [N ii]122, and far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ∼240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines (“deficits”) of line-to-FIR continuum emission for [N ii]122, , and as a function of FIR color and infrared luminosity surface density, . The median electron density of the ionized gas in LIRGs, based on the [N ii]122/[N ii]205 ratio, is = 41 cm−3. We find that the dispersion in the deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed emission, f( ) = / , which increases from ∼60% to ∼95% in the warmest LIRGs. The / ratio is tightly correlated with the PDR gas kinetic temperature in sources where is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, , and intensity of the interstellar radiation field, G, in units of and find G/ ratios of ∼0.1–50 cm3, with ULIRGs populating the upper end of the distribution. There is a relation between G/ and , showing a critical break at ≃ 5 × 1010 L⊙ kpc−2. Below , G/ remains constant, ≃0.32 cm3, and variations in are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above , G/ increases rapidly with , 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.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/8e168d64d404eb0f55393942933ef4222a1f96e1
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In Astronomy and Astrophysics
Citations in the corpus
- Detection of the Far-infrared [O iii] and Dust Emission in a Galaxy at Redshift 8.312: Early Metal Enrichment in the Heart of the Reionization Era (2018, background): “19 It is known that the [ ]L O III /LIR ratios exhibit a possible weak anti-correlation with LIR as suggested by earlier studies of local galaxies (De Looze et al. 2014; Cormier et al. 2015; Díaz-Santos et al. 2017).”
- An ALMA [C ii] Survey of 27 Quasars at z > 5.94 (2018, methodology): “Our data generally follow the trend shown in Díaz-Santos et al. (2017) for local IR-luminous galaxies, with lower [C II] EWs associated with higher FIR surface densities.”