Abstract We report the discovery of five Narrow-Line Seyfert 1 galaxies (NLS1s) identified from the ROSAT All-Sky Survey bright sources. One of them has a quasar-like luminosity and two, including the quasar-like one, have close companions and/or show interacting features. We calculate the central black hole masses and Eddington ratios for the five NLS1s. In combination with the objects of Kaspi et al., we find that NLS1s have smaller central black hole masses and higher accretion rate than normal Seyfert 1s.
Keywords black hole physics --- galaxy: active --- galaxy: Seyfert --- X-ray: galaxy
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