Virginia TechRigopoulou, D.Hopwood, R.Magdis, G. E.Thatte, N.Swinyard, B. M.Farrah, D.Huang, J. S.Alonso-Herrero, A.Bock, J. J.Clements, D. L.Cooray, A.Griffin, M. J.Oliver, S.Pearson, C.Riechers, D. A.Scott, D.Smith, A.Vaccari, M.Valtchanov, I.Wang, L.2014-02-252014-02-252014-01D. Rigopoulou et al. 2014. "HERSCHEL observations of far-infrared cooling lines in intermediate redshift (ultra)-luminous infrared galaxies," ApJ 781 L15 doi:10.1088/2041-8205/781/1/L152041-8205http://hdl.handle.net/10919/25561We report the first results from a spectroscopic survey of the [C II] 158 mu m line from a sample of intermediate redshift (0.2 < z < 0.8) (ultra)-luminous infrared galaxies, (U) LIRGs (L-IR > 10(11.5) L-circle dot), 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 mu m line emission from over 80% of the sample. We find that the [C II] line is luminous, in the range (0.8-4) x 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 similar to 10 times larger than that of local ULIRGs. Furthermore, we find that the L-[C II]/L-IR and L-[C II]/LCO(1-0) ratios in our sample are similar to those of local normal galaxies and high-z star-forming galaxies. ULIRGs at z similar to 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.en-USIn Copyrightgalaxies: starburstinfrared: galaxiesinfrared: ismsimilar-to 2c-ii linestar-formationsubmillimeter galaxies,physical conditionsphotodissociation regionsinterstellar-medium,spectroscopydeficitemissionArticle - Refereedhttp://iopscience.iop.org/2041-8205/781/1/L15/pdf/2041-8205_781_1_L15.pdfhttps://doi.org/10.1088/2041-8205/781/1/L15