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Far-infrared fine-structure line diagnostics of ultraluminous infrared galaxies

Farrah, D.; Lebouteiller, V.; Spoon, H. W. W.; Bernard Salas, J.; Pearson, C.; Rigopoulou, D.; Smith, H. A.; González-Alfonso, E.; Clements, D. L.; Efstathiou, A.; Cormier, D.; Afonso, J.; Petty, S. M.; Harris, K.; Hurley, P.; Borys, C.; Verma, A.; Cooray, A. and Salvatelli, V. (2013). Far-infrared fine-structure line diagnostics of ultraluminous infrared galaxies. Astrophysical Journal, 776(1), article no. 38.

DOI (Digital Object Identifier) Link: https://doi.org/10.1088/0004-637X/776/1/38
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Abstract

We present Herschel observations of 6 fine-structure lines in 25 ultraluminous infrared galaxies at z < 0.27. The lines, [O III]52 μm, [N III]57 μm, [O I]63 μm, [N II]122 μm, [O I]145 μm, and [C II]158 μm, are mostly single Gaussians with widths <600 km s–1 and luminosities of 107-109 L . There are deficits in the [O I]63/L IR, [N II]/L IR, [O I]145/L IR, and [C II]/L IR ratios compared to lower luminosity systems. The majority of the line deficits are consistent with dustier H II regions, but part of the [C II] deficit may arise from an additional mechanism, plausibly charged dust grains. This is consistent with some of the [C II] originating from photodissociation regions or the interstellar medium (ISM). We derive relations between far-IR line luminosities and both the IR luminosity and star formation rate. We find that [N II] and both [O I] lines are good tracers of the IR luminosity and star formation rate. In contrast, [C II] is a poor tracer of the IR luminosity and star formation rate, and does not improve as a tracer of either quantity if the [C II] deficit is accounted for. The continuum luminosity densities also correlate with the IR luminosity and star formation rate. We derive ranges for the gas density and ultraviolet radiation intensity of 101 < n < 102.5 and 102.2 < G 0 < 103.6, respectively. These ranges depend on optical type, the importance of star formation, and merger stage. We do not find relationships between far-IR line properties and several other parameters: active galactic nucleus (AGN) activity, merger stage, mid-IR excitation, and SMBH mass. We conclude that these far-IR lines arise from gas heated by starlight, and that they are not strongly influenced by AGN activity.

Item Type: Journal Item
Copyright Holders: 2013. The American Astronomical Society
ISSN: 1538-4357
Keywords: active galaxies; galactic evolution; starburst
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 40492
Depositing User: Jeronimo Bernard Salas
Date Deposited: 08 Jul 2014 09:53
Last Modified: 07 Dec 2018 10:24
URI: http://oro.open.ac.uk/id/eprint/40492
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