Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-08-29
Astronomy and Astrophysics
Astrophysics
5 pages, 4 figures. Accepted for publication in Astronomy & Astrophysics Letters
Scientific paper
10.1051/0004-6361:200500174
The Seyfert 1 galaxy NGC4151 is characterized by complex X-ray absorption, well described by a dual absorber, composed of a uniform mildly ionized gas and a cold system that partially covers the central source. However, in one of the 5 BeppoSAX observations, the spectrum shows two peculiar features. An absorption feature is detected around 8.5-9 keV with a statistical significance of 99.96%. This feature can be fitted either with an absorption edge at E=8.62^{+0.34}_{-0.52} keV with optical depth \tau=0.06\pm0.03 or with an absorption line with 9.5^{+1.3}_{-0.6} keV, width \sigma=0.95^{+1.2}_{-0.7} keV and EW= 200 eV. In the first case, we associate the feature to highly ionized iron at rest, like FeXXII-FeXXIII (E_{rest}=8.4-8.5 keV). In the second case the feature could be identified with a blend of FeXXV and FeXXVI lines, with an outflow velocity v \approx (0.09-0.26)c. This spectrum is also characterized by a substantial reduction of the absorption column density and the covering fraction of the dual absorber. In particular the column density of the mildly ionized and cold absorbers is \approx 3-5 times lower than observed in the other states, and the covering fraction is reduced by \approx 40 per cent. We propose a possible explanation linking the two properties in terms of a multi-phase ionized absorber.
Matt Giorgia
Perola Giuseppe Cesare
Piro Luigi
Rosa Adriano de
No associations
LandOfFree
Clearing up the clouds around NGC 4151: evidence of a highly ionized absorber 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 Clearing up the clouds around NGC 4151: evidence of a highly ionized absorber, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clearing up the clouds around NGC 4151: evidence of a highly ionized absorber will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-404674