Related papers: Chandra Observations of Two High-Redshift Quasars
We present deep Chandra observations of PSO J231.6576$-$20.8335, a quasar at redshift z=6.59 with a nearby (${\sim}8$ proper kpc) companion galaxy. ALMA observed both the quasar and companion to be bright in [C II], and the system has…
We present {\it Chandra} X-ray Observatory observations of Giga-Hertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources. The {\it Chandra} sample contains 13 quasars and 3 galaxies with measured 2-10 keV X-ray luminosity…
We present results from a Chandra X-ray Observatory study of the field X-ray source populations in 4 different observations: two high-redshift (z~0.5) clusters of galaxies 3C295 and RXJ003033.2+261819; and two non-cluster fields with…
The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a…
We present BeppoSAX observations of three gamma-ray emitting quasars, namely 0836+710, 1510-089 and 2230+114. The three objects have been detected up to 100 keV showing extremely flat power-law spectra above 2 keV (energy index…
We present deep (265 ks) Chandra X-ray observations of PSO J352.4034$-$15.3373, a quasar at z=5.831 that, with a radio-to-optical flux ratio of R>1000, is one of the radio-loudest quasars in the early universe and is the only quasar with…
We present new observations on PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer (LETG), using the Advanced CCD Imaging Spectrometer (ACIS). We confirm the detection of an absorption line plausibly identified as…
We present the first results of the Chandra and optical follow-up observations of hard X-ray sources detected in the ASCA Medium Sensitivity Survey (AMSS). Optical identifications are made for five objects. Three of them show either weak or…
In this work, we calculated the sizes of unresolved X-ray emission regions in three gravitationally lensed radio-loud quasars, B\,1422+231, MG\,J0414+0534 and Q\,0957+561, using a combination of imaging and spectral analysis on the X-ray…
The Chandra AO1 HETGS observation of the micro-quasar GRS 1915+105 in the low hard state reveals (1) neutral K absorption edges from Fe, Si, Mg, and S in cold gas, and (2) highly ionized (Fe XXV and Fe XXVI) absorption attributed to a hot…
We present high-resolution X-ray spectroscopy of GRB 020405 obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory starting 1.68 days after the burst. The spectrum appears featureless,…
We report the results from an ASCA observation of the high-luminosity, radio-loud quasar PKS 0637-752 (redshift 0.654), covering the 0.8-15 keV band in the quasar-frame. We find the source to have a luminosity ~10^46 erg/s in the 2-10 keV…
We present results of a study of 12 dust-reddened quasars with 0.4 < z < 2.65 and reddenings in the range 0.15 < E(B-V) < 1.7. We obtained ACIS-S X-ray spectra of these quasars, estimated the column densities towards them, and hence…
The components of the wide (7.3") separation quasar pair Q2345+007A,B (z=2.15) have the most strikingly similar optical spectra seen to date (Steidel & Sargent 1991) yet no detected lensing mass, making this system the best candidate known…
We present a systematic analysis of X-ray archival data of all the 29 quasars (QSOs) at $z$ > 5.5 observed so far with Chandra, XMM-Newton and Swift-XRT, including the most-distant quasar ever discovered, ULAS J1120+0641 ($z$ = 7.08). This…
Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they are unique probes of the early universe. To date, only few quasars have been reported at $z > 6.5$ ($<$800 Myr after the Big Bang). In this work,…
We report Chandra detection of three UV bright radio quiet quasars at $z\gtrsim5$. We have collected a sufficient number of photons to extract an X-ray spectrum of each quasar to measure their basic X-ray properties, such as the X-ray flux,…
We present a small sample of Chandra X-ray sources selected from the fields of ACIS observations which probe fluxes around the break in the hard band source counts. The targets of these fields include 9 nearby galaxy clusters, 1 distant…
We present the results of an ASCA observation of the high redshift flat spectrum radio quasar S5 0836+710. The $\sim 0.4-10$ keV X-ray spectrum is remarkably flat with $\Gamma \sim 1.4$ and substantial intrinsic absorption at low energy.…
We present optical spectra and near-infrared imaging of a sample of serendipitous X-ray sources detected in the field of Chandra observations of the A2390 cluster of galaxies. The sources have 0.5-7 keV fluxes of 0.6-8 x 10^{-14} erg…