XMM-Newton spectroscopy of high redshift quasars

Abstract

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 latter two radio-quiet. Model fits require only a power law with Galactic absorption in each case; additional intrinsic absorption is also needed for [HB89] 0438-436 and RX J122135.6+280613. The spectra are hard (Gamma \~1.7 for [HB89] 0438-436, [HB89] 2000-330 and ~1.4 for RX J122135.6+280613) with the exception of [SP89]~1107+487 which is softer (Gamma ~2.0); the combined Galactic and intrinsic absorption of lower energy X-rays in the latter source is much less significant than in the other three. The two intrinsically unabsorbed sources have greater optical fluxes relative to the X-ray contributions at the observed energies. While there is no need to include reflection or iron line components in the models, our derived upper limits (99% confidence) on these parameters are not stringent; the absence of these features, if confirmed, may be explained in terms of the high power law contribution and/or a potentially lower albedo due to the low disc temperature. However, we note that the power-law spectrum can be produced via mechanisms other than the Comptonization of accretion disc emission by a corona; given that all four of these quasars are radio sources at some level we should also consider the possibility that the X-ray emission originates, at least partially, in a jet.

arXiv commentAccepted for publication in MNRAS

References in corpus (25)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey II: Discovery of Three Additional Quasars at z>6
• ASCA observations of Seyfert 1 galaxies: II. Relativistic Iron K-alpha emission
• Broad iron lines in Active Galactic Nuclei
• A jet model for the broadband spectrum of XTE J1118+480: Synchrotron emission from radio to X-rays in the Low/Hard spectral state
• Fluorescent iron lines as a probe of astrophysical black hole systems
• Radio / X-ray correlation in the low/hard state of GX 339--4
• X-ray Spectra of a large sample of Quasars with ASCA
• A relativistic jet from Cygnus X-1 in the low/hard X-ray state
• Large-Scale, Decelerating, Relativistic X-ray Jets from the Microquasar XTE J1550-654
• Exploring the Role of Jets in the Radio/X-ray Correlations of GX339-4
• X-ray Emission Processes in Radio Jets
• Transformation Properties of External Radiation Fields, Energy-Loss Rates and Scattered Spectra, and a Model for Blazar Variability
• The very flat radio - millimetre spectrum of Cygnus X-1
• ASCA and ROSAT X-ray Spectra of High-Redshift Radio-Loud Quasars
• Chandra Discovery of a 300 kpc X-ray Jet in the GPS Quasar PKS1127-145
• The central engines of radio-quiet quasars
• Chandra Observations of Nuclear X-ray Emission from a Sample of Radio Sources
• A search for signatures of quasar evolution: Comparison of the shapes of the rest-frame optical/UV continua of quasars at z>3 and z~0.1
• A 5-GHz Southern Hemisphere VLBI Survey of Compact Radio Sources - II
• An XMM-Newton detection of the z=5.80 X-ray weak quasar SDSSp J104433.04-012502.2
• Probing the hard X-ray properties of high-redshift Radio-Quiet Quasars with ASCA
• XMM-Newton observations of four high-z quasars
• The first XMM-Newton spectrum of a high redshift quasar - PKS 0537-286
• Black Hole Blackbodies

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• XMM-Newton spectroscopy of high-redshift QSOs
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• Multiwavelength XMM-Newton observations of the Laor et al. sample of PG quasars
• XMM-Newton Observations of High Redshift Quasars
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• On the absence of molecular absorption in high redshift millimetre-band searches
• Chandra measurement of the X-ray spectrum of a quasar at z=5.99
• The Powerful Jet and Gamma-Ray Flare of the Quasar PKS 0438$-$436