| Abstract | Accurate near-infrared photometry of a selection of extragalactic emission-line objects shows an excess infrared continuum to be present in radio galaxies and to be most pronounced in Seyfert galaxies. The excess is mostly restricted to the more luminous objects. It is difficult to explain the observed colors by synchrotron radiation; in Markarian 171, the infrared continuum can be produced only by thermal radiation ... |
