Astronomy and Astrophysics – Astrophysics
Scientific paper
1999-07-09
Astronomy and Astrophysics
Astrophysics
13 pages, 6 figures, LaTeX, uses emulateapj.sty and apjfonts.sty, submitted to ApJ
Scientific paper
10.1086/308178
We present simultaneous observations by EUVE, ASCA, and RXTE of the type~1 Seyfert galaxy NGC 5548. These data indicate that variations in the EUV emission (at $\sim 0.2 $keV) appear to lead similar modulations in higher energy ($\ga 1 $keV) X-rays by $\sim$10--30 ks. This is contrary to popular models which attribute the correlated variability of the EUV, UV and optical emission in type~1 Seyferts to reprocessing of higher energy radiation. This behavior instead suggests that the variability of the optical through EUV emission is an important driver for the variability of the harder X-rays which are likely produced by thermal Comptonization. We also investigate the spectral characteristics of the fluorescent iron K$\alpha$ line and Compton reflection emission. In contrast to prior measurements of these spectral features, we find that the iron K$\alpha$ line has a relatively small equivalent width ($W_{K\alpha} \sim 100 $eV) and that the reflection component is consistent with a covering factor which is significantly less than unity ($\Omega/2\pi \sim 0.4$--0.5). Notably, although the 2--10 keV X-ray flux varies by $\sim \pm 25$% and the derived reflection fraction appears to be constant throughout our observations, the flux in the Fe~K$\alpha$ line is also constant. This behavior is difficult to reconcile in the context of standard Compton reflection models.
Blaes Omer M.
Chiang James
Madejski Greg
Magdziarz Pawel
Marshall Herman L.
No associations
LandOfFree
Simultaneous EUVE/ASCA/RXTE Observations of NGC 5548 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 Simultaneous EUVE/ASCA/RXTE Observations of NGC 5548, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Simultaneous EUVE/ASCA/RXTE Observations of NGC 5548 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-9281