UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei

Details UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei

2003-02-04

arxiv.org/abs/astro-ph/0302041v1

Astrophys.J. 587 (2003) 562-570; Erratum-ibid. 592 (2003) 1264

Astronomy and Astrophysics

Astrophysics

23 pages, 7 figures. Accepted for Publication in ApJ

Scientific paper

10.1086/376759

The narrow line region of active galaxies is formed by gas clouds surrounded by a diluted gas. Standard one-dimensional photoionization models are usually used to model this region in order to reproduce the observed emission lines. Since the narrow line region is not homogeneous, two major types of models are used: (a) those assuming a homogeneous gas distribution and a filling factor less than unity to mimic the presence of the emitting clouds; (b) those based on a composition of single-cloud models combined in order to obtain the observed spectra. The first method is largely used but may induce to misleading conclusions as shown in this paper. The second one is more appropriate, but requires a large number of observed lines in order to limit the number of single models used. After discussing the case of an extragalactic HII region, for which the ionizing radiation spectrum is better known, we show that 1-D models for the narrow line region with a filling factor less than unit do not properly mimic the clumpiness, but just simulates an overall lower density. Multi-cloud models lead to more reliable results. Both models are tested in this paper, using the emission-line spectra of two well-known Seyfert galaxies, NGC 4151 and NGC 1068. It is shown that ionizing radiation spectra with a blue bump cannot be excluded by multi-cloud models, although excluded by Alexander et al. (1999, 2000)using homogeneous models with a filling factor less than unity.

Affiliated with

Also associated with

No associations

Rating

UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-268901