Research Note Supersolar metal abundances and the Broad Line Region of Narrow-line Seyfert 1 galaxies

¹ Max-Planck-Institut für extraterrestrische Physik, Postfach 1603, 85740 Garching, Germany
² The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA

Corresponding author: S. Komossa, skomossa@xray.mpe.mpg.de

Received: 12 February 2001
Accepted: 5 June 2001

Abstract

Narrow-line Seyfert 1 galaxies (NLSy1) are intriguing due to their extreme continuum and emission line properties which are not yet well understood. This paper is motivated by the recent suggestion that NLSy1 galaxies might be young active galactic nuclei (AGNs) and that they may have supersolar metal abundances. We have examined the stability of broad emission line region (BLR) clouds under isobaric perturbation and its dependence on gas metal abundances. We show that supersolar metallicity increases the range where multiple phases in pressure balance may exist. This is particularly important for NLSy1s with steep X-ray spectra where it delays the trend of hindrance of a multi-phase equilibrium. Finally, the role of warm absorbers in the context of this scenario is assessed.