Properties of OH megamaser galaxies in the radio continuum. II. Data analysis

The properties of OH megamaser galaxies in the radio continuum are discussed. Many radio sources in OH megamaser galaxies exhibit relatively flat (alpha >= -0.5) radio spectra between frequencies of 1.49 and 8.44 GHz along with high brightness temperatures (T-b >= 10(4) K). In these galaxies the line and radio continuum fluxes are not correlated. The continuum radio emission of OH megamasers is predominantly nonthermal and is associated either with an active nucleus or with compact star formation. The thermal component of the radio emission from these galaxies can be neglected. The observed flat radio spectra and high brightness temperatures imply the existence of an active galactic nucleus, although some megamasers may be associated with compact star formation.