Exploratory Chandra Observations of the Highest-Redshift Quasars: X-rays from the Dawn of the Modern Universe

Abstract

We report exploratory Chandra observations of 14 high-redshift (z=4.06-5.27), optically selected quasars. Ten of these quasars are detected, increasing the number of z>4 X-ray detected quasars by 71%. Our detections include four of the five highest-redshift X-ray detected quasars to date, among them SDSSp J021043.17-001818.4, the highest-redshift (z=4.77) radio-loud quasar detected in the X-ray band. The four undetected objects are the Broad Absorption Line quasars SDSSp J112956.10-014212.4 and SDSSp 160501.21-011220.0, the weak emission-line quasar SDSSp J153259.96-003944.1, and the quasar PSS 1435+3057. A comparison of the quasars' spectral energy distributions (by means of the optical-to-X-ray spectral index, alpha_ox) with those of lower-redshift samples indicates that the Chandra quasars are X-ray fainter by a factor of approx 2. X-ray faintness could be associated with the presence of large amounts of gas in the primeval galaxies harboring these high-redshift quasars, as suggested by recent studies conducted on z>4 quasars in other bands. Using the current Chandra data, predictions for the next generation of X-ray observatories, Constellation-X and Xeus, are also provided.

13 pages, 7 figures included, LaTeX emulateapj5.sty, accepted for publication by the Astronomical Journal

References in corpus (43)

• The Sloan Digital Sky Survey: Technical Summary
• Composite Quasar Spectra From the Sloan Digital Sky Survey
• Elemental Abundances in QSOs: Star Formation and Galactic Nuclear Evolution at High Redshifts
• X-ray Spectra of a large sample of Quasars with ASCA
• On the Nature of Soft X-ray Weak Quasi-Stellar Objects
• The Discovery of a Luminous z=5.80 Quasar from the Sloan Digital Sky Survey
• Simulation of Stellar Objects in SDSS Color Space
• Molecular gas and dust around a radio-quiet quasar at redshift 4.7
• X-ray Observations of Optically-Selected, Radio-Quiet Quasars I: The ASCA results
• Mitigating Charge Transfer Inefficiency in the Chandra X-ray Observatory's ACIS Instrument
• A Chandra Survey of Broad Absorption Line Quasars
• A 1.2mm MAMBO/IRAM-30m Survey of Dust Emission from the Highest Redshift PSS Quasars
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data
• The Chandra Deep Survey of the Hubble Deep Field North Area. IV. An Ultradeep Image of the HDF-N
• The Discovery of a High-redshift Quasar without Emission Lines from Sloan Digital Sky Survey Commissioning Data
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data III: A Color Selected Sample at i^*<20 in the Fall Equatorial Stripe
• A 250 GHz Survey of High Redshift QSOs from the Sloan Digital Sky Survey
• ASCA and ROSAT X-ray Spectra of High-Redshift Radio-Loud Quasars
• Exploratory ASCA Observations of Broad Absorption Line Quasi-Stellar Objects
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data VI. Sloan Digital Sky Survey Spectrograph Observations
• 350 Micron Dust Emission from High Redshift Objects
• Radio Properties of z>4 Optically-Selected Quasars
• Heavy X-ray Absorption in Soft X-ray Weak Active Galactic Nuclei
• X-ray Spectral Survey of WGACAT Quasars, I: Spectral Evolution & Low Energy Cut-offs
• NICMOS Imaging of the Dusty Microjansky Radio Source VLA J123642+621331 at z = 4.424
• Submillimetre observations of luminous z>4 radio-quiet quasars and the contribution of AGN to the submm source population
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data II: The Spring Equatorial Stripe
• PMN J0525-3343: soft X-ray spectral flattening in a blazar at z=4.4
• Sensitive Radio Observations of High Redshift Dusty QSOs
• Five High-Redshift Quasars Discovered in Commissioning Imaging Data of the Sloan Digital Sky Survey
• High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data V. Hobby-Eberly Telescope Observations
• An XMM-Newton detection of the z=5.80 X-ray weak quasar SDSSp J104433.04-012502.2
• The X-ray Properties of z>4 Quasars
• Probing the hard X-ray properties of high-redshift Radio-Quiet Quasars with ASCA
• The blazar GB1428+4217: a warm absorber at z=4.72?
• Detection of CO (2-1) and Radio Continuum Emission from the z = 4.4 QSO BRI 1335-0417
• The QSO variability-luminosity-redshift relation
• PKS 1004+13: A High-Inclination, Highly-Absorbed Radio-Loud QSO -- The First Radio-Loud BAL QSO at Low Redshift?
• Evidence of thick obscuring matter revealed in the X-ray spectrum of the Z=4.28 quasar RXJ1028.6-0844
• The 3-53 keV Spectrum of the Quasar 1508+5714: X-rays from z = 4.3
• Discovery of strong CIV absorption in the highest redshift quasar
• The Second APM UKST Colour Survey for z>4 Quasars
• A deep ROSAT survey XV. the average QSO spectrum and its evolution

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• The X-ray Spectral Properties of SCUBA Galaxies
• X-ray emission from radio-quiet quasars in the SDSS Early Data Release. The alpha_ox dependence upon UV luminosity
• The Chandra Deep Field-North Survey. XIV. X-ray detected Obscured AGNs and Starburst Galaxies in the Bright Submm Source Population
• High-Redshift SDSS Quasars with Weak Emission Lines
• The Mean Star-Forming Properties of QSO Host Galaxies
• An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: The AGN Fraction and X-ray Properties of Submillimeter Galaxies
• Chandra Observations of the Highest Redshift Quasars from the Sloan Digital Sky Survey
• The Intrinsically X-ray Weak Quasar PHL 1811. II. Optical and UV Spectra and Analysis
• Observational Constraints on the Dependence of Radio-Quiet Quasar X-ray Emission on Black Hole Mass and Accretion Rate
• X-ray Lighthouses of the High-Redshift Universe. II. Further Snapshot Observations of the Most Luminous z>4 Quasars with Chandra
• The Chandra Multiwavelength Project: Optical Followup of Serendipitous Chandra Sources
• Chandra Survey of Radio-quiet, High-redshift Quasars
• The X-ray Spectral Properties and Variability of Luminous High-Redshift Active Galactic Nuclei
• Chandra and XMM-Newton observations of the first quasars: X-rays from the age of cosmic enlightenment
• Quasars as standard candles II: The non linear relation between UV and X-ray emission at high redshifts
• Evolution of the X-ray Emission of Radio-Quiet Quasars
• Exploratory Chandra Observations of the Three Highest Redshift Quasars Known
• X-ray lighthouses of the high-redshift Universe. Probing the most luminous z>4 Palomar Digital Sky Survey Quasars with Chandra
• An X-ray and Multiwavelength Survey of Highly Radio-Loud Quasars at z > 4: Jet-Linked Emission in the Brightest Radio Beacons of the Early Universe
• Chandra Observations of Radio-Loud Quasars at z > 4: X-rays from the Radio Beacons of the Early Universe
• The X-ray/UV ratio in Active Galactic Nuclei: dispersion and variability
• XMM-Newton observations of high-luminosity radio-quiet QSOs
• XMM-Newton Observations of High Redshift Quasars
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• A Chandra Search for X-Ray Jets in Redshift 6 Quasars
• Chandra and MMT observations of low-mass black hole active galactic nuclei accreting at low rates in dwarf galaxies
• The Chandra Deep Field-North Survey. XVI. The X-ray properties of moderate-luminosity Active Galaxies at z>4
• X-ray spectroscopy of the z=6.4 quasar J1148+5251
• MM-Newton Observations of two high redshift quasars: RX J1028-0844 and BR 0351-1034
• Discovery of a z=4.93, X-ray selected quasar by the Chandra Multiwavelength Project (ChamP)
• Serendipitous AGN in the XMM-Newton fields of Markarian 205 and QSO 0130-403
• A Chandra Snapshot Survey of Representative High-Redshift Radio-Loud Quasars from the Parkes-MIT-NRAO Sample
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• Discovery of Compton-thick quasars in the Sloan Digital Sky Survey
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• Exploratory X-ray Monitoring of Luminous Radio-Quiet Quasars at High Redshift: No Evidence for Evolution in X-ray Variability
• Constraints on the X-ray Luminosity Function of AGN at z=5.7-6.4 with the Extragalactic Serendipitous Swift Survey
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• Outflowing material in the zem = 4.92 BAL QSO SDSS~J160501.21-011220.0
• Chandra Observations of Six QSOs at z $\approx$ 3
• Rest-frame optical continua of L ~ L*, z>3 quasars: probing the faint end of the high z quasar luminosity function
• X-rays from the High-Redshift Universe: The Chandra view
• Exploratory X-Ray Monitoring of Luminous Radio-Quiet Quasars at High Redshift: Extended Time-Series Analyses and Stacked Imaging Spectroscopy
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