- Rigopoulou, D
- Hopwood, R
- Magdis, GE
- Thatte, N
- Swinyard, BM
- Farrah, D
- Huang, JS
- Alonso-Herrero, A
- Bock, JJ
- Clements, D
- Cooray, A
- Griffin, MJ
- Oliver, S
- Pearson, C
- Riechers, D
- Scott, D
- Smith, A
- Vaccari, M
- Valtchanov, I
- Wang, L
- et al.
We report the first results from a spectroscopic survey of the [C II] 158 μm line from a sample of intermediate redshift (0.2 1011.5 L ), using the Spectral and Photometric Imaging REceiver-Fourier Transform Spectrometer on board the Herschel Space Observatory. This is the first survey of [C II] 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 [C II] 158 μm line emission from over 80% of the sample. We find that the [C II] 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 photodissociation regions on the surface of molecular clouds. The L [C II]/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 [C II]/L IR and L [C II]/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. © 2014. The American Astronomical Society. All rights reserved.