ﻻ يوجد ملخص باللغة العربية
X-ray spectroscopy of Seyfert 1 galaxies often reveal absorption edges resulting from photoionized gas along the line-of-sight to the central engine, the so-called warm absorber. I discuss how recent ASCA observations of warm absorber variability in MCG-6-30-15 can lead us to reject a one-zone model and, instead, have suggested a multi-zone warm absorber. The evidence for dust within the warm absorbers of MCG-6-30-15 and IRAS 13349+2438 is also addressed. These dusty warm absorbers reveal themselves by significantly reddening the optical flux without heavily absorbing the soft X-ray photons. Thermal emission from this warm/hot dust may be responsible for the infra-red bump commonly seen in the broad band spectrum of many Seyfert galaxies.
We present both phenomenological and more physical photoionization models of the Chandra HETG spectra of the Seyfert-1 AGN NGC 4051. We detect 40 absorption and emission lines, encompassing highly ionized charge states from O, Ne, Mg, Si, S and the F
We collate the results of recent high resolution X-ray spectroscopic observations of 23 AGN, and use the resulting information to try to provide answers to some of the main open questions about warm absorbers: where do they originate, what effect do
The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its
This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the
We report the detection of the 3.3 mu Polycyclic Aromatic Hydrocarbon (PAH) feature in two Seyfert 1 galaxies - NGC 3227 and Mrk 766, and one QSO - Mrk 478, observed with SpeX at IRTF at a spectral resolution not previously attained for this type of