ABSTRACT

By means of models for supernovae of type II during the photospheric phase and for accretion disks around (super–)massive black holes it is found that the pressures, temperatures and velocities in the spectrum-forming regions are quite comparable so that the energy distributions have to be similar. The observed similarity of moderate resolution optical spectra from supernovae of type II and from active galactic nuclei may therefore be just fortuitously. For the distinction of these classes of objects in particular line profiles can be used in addition to gamma–iay fluxes and polarization data.

INTRODUCTION

Optical spectra of type II supernovae (abbreviated subsequently “SNell”) during the photospheric phase look often very similar to those of active galactic nuclei (AGNs, see e.g. Filippenko 1992). This similarity was used by Terlevitch and Melnick (1985, see also subsequent papers by Terlevitch) to support the hypothesis that the activity of galaxies is caused by starbursts that produce lots of massive stars which subsequently explode as supernovae. On the other hand, there are many convincing, though indirect arguments that the optical/UV luminosity of AGNs is produced by disks around (super-)massive black holes (see e.g. Shields 1978; Rees 1984; Malkan 1991).

Since unique spectral signatures of accretion disks have still to be found this raises the following questions:

1. (i) is the optical light of AGNs indeed produced predominantly by SNell?

2. (ii) what does the similarity tell us, if the AGN spectra are in fact produced by accretion disks?

3. […]