| Description |
We propose to exploit the spectroscopic capabilities of PACS to describe the C IIline emission in a unique and comprehensive sample of star-forming galaxies selectedfrom the wide-field, parallel PACS+SPIRE H-ATLAS imaging survey.The sample has exquisite optical spectra from GAMA and SDSS, allowing us to:1 describe C II line as a function of dust and stellar mass, metallicity, extinction, dust temperature, and many other physical parameters;2 identify the parameters controlling the behaviour of CII/L(FIR) at log L(FIR)>11;3 calibrate CII as a star-formation indicator exploiting our accurate L(FIR) and L(Halpha) and determine the range over which it is valid.CII is potentially an unrivalled tracer of the total gas mass in galaxies (intheory better than CO), and it is therefore an increasingly important observable,e.g. for upcoming ALMA observations of distant galaxies. Our study will become thebenchmark for the interpretation of high-z observations, with a legacy value thatwill survive well into the SPICA era.Some of the key advantages of this proposal over previous Herschel studies such asSHINING and HerCULES are:- we cover 10.2 < log L(FIR) < 11.5 and are unbiased towards powerful ULIRGs with complex merger morphologies;- our sample is selected blindly from H-ATLAS rather than from IRAS, and thus allows exploration of comprehensive parameter space and is much less biased towards galaxies with warm dust emission;- we know the spatial extent of the galaxies, allowing reliable flux measurements via a single pointing within 10 min/target.We can thus achieve our goals in a systematic fashion, maximising the parameter spacefor the diagnostics of interest.We stress that the scientific legacy of ISO and Spitzer has in large part been basedon the wealth of data in their spectroscopic archives and the same will likely betrue for Herschel. |
