Herschel observations of far-infrared cooling lines in intermediate redshift (ultra)-luminous infrared galaxies

Rigopoulou, D, Hopwood, R, Magdis, G E, Thatte, N, Swinyard, B M, Farrah, D, Huang, J-S, Alonso-Herrero, A, Bock, J J, Clements, D, Cooray, A, Griffin, M J, Oliver, S, Pearson, C, Riechers, D, Scott, D, Smith, A, Vaccari, M, Valtchanov, I and Wang, L (2014) Herschel observations of far-infrared cooling lines in intermediate redshift (ultra)-luminous infrared galaxies. The Astrophysical Journal Letters, 781 (1). L15. ISSN 2041-8205

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We report the first results from a spectroscopic survey of the [Cii] 158 μm line from a sample of intermediate redshift (0.2 < z < 0.8) (ultra)-luminous infrared galaxies, (U)LIRGs (L IR > 10 11.5 L ? ), using the Spectral and Photometric Imaging REceiver–Fourier Transform Spectrometer on board the Herschel Space Observatory. This is the first survey of [Cii] emission, an important tracer of star formation, at a redshift range where the star formation rate density of the universe increases rapidly. We detect strong [Cii] 158 μm line emission from over 80% of the sample. We find that the [Cii] line is luminous, in the range (0.8–4) × 10 −3 of the far-infrared continuum luminosity of our sources, and appears to arise from photo dissociation regions on the surface of molecular clouds. The L [Cii] /L IR ratio in our intermediate redshift (U)LIRGs is on average ∼ 10 times larger than that of local ULIRGs. Furthermore, we find that the L [Cii] /L IR and L [Cii] /L CO(1 – 0) ratios in our sample are similar to those of local normal galaxies and high-z star-forming galaxies. ULIRGs at z ∼ 0.5 show many similarities to the properties of local normal and high-z star-forming galaxies. Our findings strongly suggest that rapid evolution in the properties of the star-forming regions of (U)LIRGs is likely to have occurred in the last 5 billion years.

Item Type: Article
Keywords: galaxies: starburst – infrared: galaxies – infrared: ISM
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy > QB0460 Astrophysics
Depositing User: Richard Chambers
Date Deposited: 08 Jun 2015 14:48
Last Modified: 02 Jul 2019 21:48
URI: http://sro.sussex.ac.uk/id/eprint/54331

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