Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-06-14
Astronomy and Astrophysics
Astrophysics
23 pages, 41 figures, accepted for publication in A&A
Scientific paper
10.1051/0004-6361:20065477
While [OIII] narrow-band imaging is commonly used to measure the size of the narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be contaminated by emission from surrounding starbursts. Recently, we have shown that long-slit spectroscopy provides a valuable alternative approach to probe the size in terms of AGN photoionisation. Moreover, several parameters of the NLR can be directly accessed. We here apply the same methods developed and described for the Seyfert-2 galaxy NGC1386 to study the NLR of five other Seyfert-2 galaxies by using high-sensitivity spatially-resolved optical spectroscopy obtained at the VLT and the NTT. We probe the AGN-photoionisation of the NLR and thus, its ``real'' size using diagnostic line-ratio diagrams.We derive physical properties of the NLR such as reddening, ionisation parameter, electron density, and velocity as a function of distance from the nucleus. For NGC5643, the diagnostic diagrams unveil a similar transition between line ratios falling in the AGN regime and those typical for HII regions as found for NGC1386, thus determining the size of the NLR. For the other four objects, all measured line ratios fall in the AGN regime. In almost all cases, both electron density and ionisation parameter decrease with radius. Deviations from this general behaviour (such as a secondary peak) seen in both the ionisation parameter and electron density can be interpreted as signs of shocks from the interaction of a radio jet and the NLR gas. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We compare our results to those of NGC1386 and show that the latter can be considered as prototypical also for this larger sample. We discuss our findings in detail for each object.
Bennert Nicola
Chini Rolf
Haas Martin
Jungwiert Bruno
Komossa Stefanie
No associations
LandOfFree
Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy 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 Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-605951