On the nature of the so-called narrow-line X-ray galaxies

Six X-ray emitting galaxies are known which are called narrow-emission line galaxies. Spectroscopic and photographic observations show that two of them (NGC 1365 and NGC 2992) have both a star-like nucleus and a broad H alpha component; NGC 5506 has a star-like nucleus, but the authors were unable to detect a broad H alpha component; A 0945-30 has no visible star-like nucleus but possibly shows a broad H alpha component; NGC 2110, an elliptical galaxy, has no visible star-like nucleus and was not observed spectroscopically; NGC 7582 was not observed at all. The authors' observations suggest that all these galaxies could have a Seyfert 1 nucleus partially hidden behind a dark absorbing cloud. (15 refs).