The optical continuum properties of the nuclei of radio galaxies, Seyfert galaxies, N systems, BL Lac Objects, and QSOs are reviewed. The observations are in the main consistent with the hypothesis of contributions in varying degrees for a stellar component and a small non-thermal source. The presence of dust strongly influences the continuum spectrum and polarization in the case of Seyferts. The observations have not as yet led to an understanding of the nature of the non-thermal continuum source but offer prospects of so doing.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Mathematical Physics
- Condensed Matter Physics