No CrossRef data available.
Published online by Cambridge University Press: 26 January 2006
Molecular emissions are powerful tracers of intense heating andstar-formation processes. In this paper we consider thecharacteristics of Megamaser emission that originate in some activenuclei that are powered by intense star-formation or accretion onto amassive compact object. The OH and possibly the H2CO Megamaseractivity occurs among the most luminous sources in the population of(Ultra-) Luminous Infrared Galaxies. In addition, we consider thesystematic behaviour of the line emission of high-density tracermolecules. An evolutionary scenario is presented for ULIRGs that mayexplain the molecular line ratios observed in the population of FIRgalaxies.