EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 371/ 2 Article

Free access article

Issue A&A
Volume 371, Number 2, May IV 2001
Page(s) 507 - 511
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010404



A&A 371, 507-511 (2001)
DOI: 10.1051/0004-6361:20010404

A two-phase model for the narrow line region of NGC 4151

S. Komossa

Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany

(Received 9 February 2001 / Accepted 16 March 2001)

Abstract
NGC 4151 is one of the brightest and best-studied Seyfert galaxies. Here, we present a two-phase model of the narrow-line region (NLR) of NGC 4151. This study is motivated by (i) the fact that the X-ray spectrum of NGC 4151 is among the flattest known for Seyferts, and (ii) the recent Chandra detection of an X-ray narrow-line region in this galaxy. X-ray spectra as flat as that of NGC 4151 ( $\Gamma_{\rm x}$ $\simeq -1.5$) are expected to favor the presence of two gas phases in pressure equilibrium (Krolik et al. 1981). In the present study, we show that a pronounced two-phase equilibrium develops in the extended emission-line region if we use the observed multi-wavelength spectrum of NGC 4151 to ionize the clouds. The material is stable to isobaric perturbations over a wide range of temperatures. We therefore propose that such a condition has arisen in the NLR of NGC 4151, and that it explains the detection of hot, extended X-ray gas which we identify as the NLR-cloud confining medium.


Key words: galaxies: Seyfert -- galaxies: individual: NGC 4151 -- galaxies: nuclei -- galaxies: emission lines -- X-rays: galaxies

Offprint request: S. Komossa, skomossa@xray.mpe.mpg.de

SIMBAD Objects



© ESO 2001

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.