Black holes in AGN: recent results on IC 4329a and NGC 4945
✍ Scribed by G. Madejski; Ch. Done; P. Zycki
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 326 KB
- Volume
- 320
- Category
- Article
- ISSN
- 0004-6337
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✦ Synopsis
This paper briefly reviews the observations which provide the best evidence for the presence of black holes in active galaxies: kinematic studies using optical emission lines as well as the distribution of megamaser spots; X-ray variability; and the profile of the Fe Kα X-ray emission line. It summarizes the current popular models for the radiative processes operating in radio-quiet AGN. Finally, it presents two recent X-ray observations of AGN, where (1) the shape of the Fe K line indicates a diversity of locations where such lines originate (based on the ASCA & RXTE data for IC 4329a and NGC 5548), and (2) the rapid hard X-ray variability measured with the RXTE in the heavily absorbed Seyfert 2 NGC 4945 implies that the Thomson-thick absorber surrounding the nucleus (with τ 2.4) is unlikely to subtend a large solid angle to the nucleus, meaning that it is not geometrically thick, but is confined to a rather thin, disk-like structure.