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Today's Colloquium: Studying the dark hearts of luminous infrared galaxies with Herschel

Submitter: Colloquium
Description: Speaker: Rowin Meijerink (Leiden Observatory)

Luminous and ultraluminous infrared galaxies ((U)LIRGs) are among the most spectacular objects in the local universe as far as their energy output is concerned. While they are locally fairly rare, star formation becomes more and more dominated by these galaxies as we look back towards higher redshifts.

Optical studies of the energy sources of (U)LIRGs are hampered by their large obscuring column densities of dust, but the concomitant molecular gas provides unique probes of local conditions in far-infrared and submillimetre spectral lines. With this in mind, we have embarked on the Herschel Comprehensive (U)LIRG Emission Survey (HerCULES), an Open Time Key Program on the Herschel Space Observatory. In this program, we obtained full 194-671 micron spectra (plus spectra of the principal infrared cooling lines at shorter wavelengths) of a complete sample of 29 (U)LIRGs.

I will discuss first results of HerCULES and related projects, including (i) the use of the CO rotational ladder and other lines to separate star formation and AGN power; and (ii) the H2O rotational lines as probes of local physical conditions. These lines will become key diagnostics of high-z galaxies in the ALMA era, and it is therefore imperative to understand them in local galaxies. I will also discuss prospects for the study of high-redshift counterparts.
Copyright: Rowin Meijerink & Paul van der Werf
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