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Low-Activity Nuclei in Spiral Galaxies

Published online by Cambridge University Press:  07 August 2017

G. Fabbiano
G. Fabbiano*
Affiliation:
Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA

Extract

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Two types of active nuclei have been observed in normal spiral galaxies in X-rays with the Einstein Observatory: low-activity AGN, and starburst regions. The prototype of the first kind is the nucleus of M81 (Elvis and Van Speybroeck 1982; Fabbiano 1988a), but similar nuclei might also be those of M33 and NGC 1313. Soft X-ray spectra of these nuclei suggest relatively steep soft X-ray components (Trinchieri, Fabbiano and Peres 1988; Fabbiano and Trinchieri 1987; Fabbiano 1988a), reminiscent of those observed in QSOs by Bechtold et al (1987) and Wilkes and Elvis (1987). In M81, in particular, this soft component might supply enough photons to explain the optical line spectrum. If this soft X-ray component originates from an accretion disk surrounding a central black hole, the mass of the latter is likely to be smaller than 104–5 solar masses.

Type
Part 9: Intrinsically Weak AGNs
Information
Symposium - International Astronomical Union , Volume 134: Active Galactic Nuclei , 1989 , pp. 517
Copyright
Copyright © Kluwer 1989 

References

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