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Past X-ray observations by ASCA suggest that warm absorbers (O VII and O VIII edges) are apparently rare in high luminosity AGNs (quasars) while they are more common in low luminosity AGNs (Seyferts). However, this could be a selection effect if high luminosity AGNs have mostly narrow absorption lines (with no strong bound free edges), which escaped detection by the low resolution of ASCA. To check this hypothesis we are studying the high-resolution X-ray spectra of quasars from grating spectrometers on board Chandra and XMM-Newton in search for absorption lines. In this contribution we present spectra of three quasars. The spectra show narrow (several hundred km/s) absorption and emission X-ray lines from H-like and He-like ions of O, Ne, Mg, and other abundant elements. We also detect absorption from iron L-shell lines and iron M-shell unresolved transition array. We present the analysis of MR2251-178 where we find that at least two, and probably three, distinct warm absorbers are needed to explain the high resolution spectrum of this object. We re-analyze the high-resolution X-ray spectrum of PG1211+143 and suggest that an outflow velocity of about 3000 km/s provides an adequate explanation to these data. We also present preliminary results form the Chandra/HETGS observation of the quasar 4C74.26.
We examine deep XMM-Newton Reflection Grating Spectrometer (RGS) spectra from the cores of three X-ray bright cool core galaxy clusters, Abell 262, Abell 3581 and HCG 62. Each of the RGS spectra show Fe XVII emission lines indicating the presence of
X-ray line profiles represent a new way of studying the winds of massive stars. In particular, they enable us to probe in detail the wind-wind collision in colliding wind binaries, providing new insights into the structure and dynamics of the X-ray-e
We present new hard X-ray spectra of three radio-loud AGNs of moderately high X-ray luminosity (L_x ~ 10^45 erg/s; PKS 2349-01, 3C 323.1, and 4C 74.26) obtained with ASCA and BeppoSAX. The X-ray continua are described in all three cases with a power
We present a survey of six low to moderate redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the Warm-Hot Intergalactic Medium. All the X-ray spectra
High-energy astrophysics is a relatively young scientific field, made possible by space-borne telescopes. During the half-century history of x-ray astronomy, the sensitivity of focusing x-ray telescopes-through finer angular resolution and increased