Herschel Observations of Far-Infrared Cooling Lines in intermediate Redshift (Ultra)-luminous Infrared Galaxies

Journal article

We report the first results from a spectroscopic survey of the [CII] 158um line from a sample of intermediate redshift (0.210^11.5 Lsun), using the SPIRE-Fourier Transform Spectrometer (FTS) 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] 158um line emission from over 80% of the sample. We find that the [CII] line is luminous, in the range (0.8-4)x10^(-3) of the far-infrared continuum luminosity of our sources, and appears to arise from photodissociation regions on the surface of molecular clouds. The L[CII]/LIR 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]/LIR and L[CII]/LCO(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 luminous infrared galaxies is likely to have occurred in the last 5 billion years.

Authors: Rigopoulou, D; Hopwood, R; Magdis, G; Thatte, N; Swinyard, B

• Publication status: Published
• Publisher: Institute of Physics Publishing
• Journal: ASTROPHYSICAL JOURNAL LETTERS
• Volume: 781
• Issue: 1
• Pages: L15-L15
• Publication date: 2014-01-10
• DOI: 10.1088/2041-8205/781/1/L15
• EISSN: 2041-8213
• ISSN: 2041-8205
• Language: English
• Keywords: astro-ph.CO; astro-ph.GA