MM-observations of Markarian galaxies

We present high sensitivity continuum measurements at 1300μm of 14 Markarian galaxies. The spectral index between 100 and 1300μm clearly indicates that the emission must be thermal radiation from dust. We find a relation L ∝ Mg0.72 between Mg and the total luminosity L of the galaxies. At the low luminosity end classical star burst galaxies like M82 or NGC253 also follow this relation. This implies that the basic parameter for the strength of the activity is the gas mass. Recently, a very similar dependence L ∝ Mg0.9 was found to hold for nonactive galaxies and visually obscured HII regions, but with L/Mg a factor of 20 lower. We conclude that a galaxy can be in either one of two modes: active or inactive. In both modes the luminosity is roughly proportional to the gas mass and therefore originates from star formation