Related papers: Chandra Observations of Two High-Redshift Quasars
We observed MS 1054-0321, the highest redshift cluster of galaxies in the Einstein Medium Sensitivity Survey (EMSS), with the Chandra ACIS-S detector. We find the X-ray temperature of the cluster to be 10.4^{+1.7}_{-1.5} keV, slightly lower…
Results are presented on the X-ray properties of 9 high-redshift (1.2 < z < 3.4) radio-loud quasars (RLQs) observed by ASCA (10 observations) and ROSAT (11 observations, for a subset of 6 quasars). New ASCA observations of S5 0014+81 (z =…
We present new Chandra observations of 21 z>4 quasars, including 11 sources at z>5. These observations double the number of X-ray detected quasars at z>5, allowing investigation of the X-ray spectral properties of a substantial sample of…
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…
ASCA observations of 4 high redshift radio--loud quasars with 1.44$<$z$<$3.21 are presented. The spectral analysis for three of them (PKS 0332-403, PKS 0537-286, PKS 2149-306) reveals that their X-ray continuum emission is well represented…
We present some early results on AGN from the Chandra X-ray Observatory, highlighting high resolution spectroscopy using the High Energy Transmission Grating Spectrometer (HETGS). The quasar PKS 0637-752 was found to have a very bright…
We observed 17 optically-selected, radio-quiet high-redshift quasars with the Chandra Observatory ACIS, and detected 16 of them. The quasars have redshift between 3.70 and 6.28 and include the highest redshift quasars known. When compared…
We report on Chandra observations of three quasars SDSSP J083643+005453, SDSSP J103027+052455, and SDSSP J130608+035626 at redshifts 5.82, 6.28 and 5.99 respectively. All the three sources are clearly detected in the X-ray band, up to rest…
We report on Chandra observations of a sample of 11 optically luminous (Mb<-28.5) quasars at z=3.96-4.55 selected from the Palomar Digital Sky Survey and the Automatic Plate Measuring Facility Survey. These are among the most luminous z>4…
Quasars at early redshifts ($z > 6$) with companion galaxies offer unique insights into the growth and evolution of the first supermassive black holes. Here, we report on a 150 ks Chandra observation of PSO J308.0416$-$21.2339, a $z=6.23$…
We observed B1600+434 and B1608+656 with CXO/ACIS, detecting both quasar images in B1600+434 and three of four images in B1608+656. We did not detect significant X-ray emission from nearby galaxy groups or clusters associated with each lens…
The X-ray bright z=0.116 quasar PKS 2155-304 is frequently observed as a Chandra calibration source, with a total of 483 ksec of Low Energy Transmission Grating (LETG) exposure time accumulated through May 2006. Highly-ionized metal…
We present the observations of the gravitationally lensed system QSO 2237+0305 performed with the Chandra X-ray Observatory on 2000 Sept. 6, and on 2001 Dec. 8 for 30.3 ks and 9.5 ks, respectively. Imaging analysis resolves the four X-ray…
We are carrying out sensitive X-ray observations with Chandra and XMM of type II quasars selected from the Sloan Digital Sky Survey based on their optical emission line properties. We present observations of four objects at redshifts 0.4 <…
X-ray observations provide a unique probe of the accretion disk corona of supermassive black holes (SMBHs). In this paper, we present a uniform \emph{Chandra} X-ray data analysis of a sample of 152 $z\geq4.5$ quasars. We firmly detect 46…
We present XMM-Newton X-ray spectra and optical photometry of four high redshift (z=2.96-3.77) quasars, [HB89] 0438-436, [HB89] 2000-330, [SP89] 1107+487 and RX J122135.6+280613; of these four objects the former two are radio-loud, the…
Chandra snapshot observations of the three most distant quasars then known, at redshifts 5.82, 5.99, and 6.28, gave signficant detections even in the short, 6 -- 8 ks, observations. The X-ray to optical luminosity ratios indicate that…
We present the first X-ray detection of resonant absorption from warm/hot local gas either in our Galaxy, or in the Intergalactic space surrounding our Galaxy, along the line of sight toward the blazar PKS 2155-304. The Chandra HRCS-LETG…
We present $Beppo$SAX observations of the $\gamma $-ray emitting quasars 0836+710, 1510-089 and 2230+114. All the objects have been detected in the PDS up to 100 keV and have extremely flat power-law spectra above 2 keV ($\alpha…
We present the results of XMM-Newton observations of four high-z quasars, two radio-loud and two radio-quiet. One of the radio-loud objects, PKS 2126-158, clearly shows absorption in excess of the galactic value as claimed before from ASCA…