The chandra deep field-north survey. XVI. The x-ray properties of moderate-luminosity active galaxies at z > 4

C. Vignali; F. E. Bauer; D. M. Alexander; W. N. Brandt; A. E. Hornschemeier; D. P. Schneider; G. P. Garmire

doi:10.1086/345751

The chandra deep field-north survey. XVI. The x-ray properties of moderate-luminosity active galaxies at z > 4

C. Vignali, F. E. Bauer, D. M. Alexander, W. N. Brandt, A. E. Hornschemeier, D. P. Schneider, G. P. Garmire

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Abstract

We present X-ray spectral analyses of the three z > 4 active galactic nuclei (AGNs) thus far spectroscopically identified in the Chandra Deep Field-North Survey, at redshifts of 5.186, 4.424, and 4.137. These analyses are made possible by the extremely deep exposure (≈2 Ms) and the low Chandra background. The rest-frame ≈2.5-40 keV spectra are the first for optically faint (two of the three sources have I > 24) z > 4 AGNs. The z = 5.186 quasar is well fitted by a power-law model with photon index Γ = 1.8 ± 0.3, consistent with those of lower-redshift, unobscured AGNs. The other two AGNs have flatter effective X-ray photon indices (Γ ≈ 1.1-1.5), suggesting the presence of intrinsic absorption (provided their underlying X-ray continua are similar to those of lower redshift AGNs). It is possible that the flat X-ray continuum of the z = 4.424 AGN is partially related to its radio loudness. If the z = 4.137 AGN suffers from X-ray absorption, the implied column density is N_H 2 × 10 ²³ cm^-2.

Original language	English (US)
Pages (from-to)	L105-L109
Journal	Astrophysical Journal
Volume	580
Issue number	2 II
DOIs	https://doi.org/10.1086/345751
State	Published - Dec 1 2002

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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@article{a8fd4dc2dc7b4b8b93ec02912d6d3af1,

title = "The chandra deep field-north survey. XVI. The x-ray properties of moderate-luminosity active galaxies at z > 4",

abstract = "We present X-ray spectral analyses of the three z > 4 active galactic nuclei (AGNs) thus far spectroscopically identified in the Chandra Deep Field-North Survey, at redshifts of 5.186, 4.424, and 4.137. These analyses are made possible by the extremely deep exposure (≈2 Ms) and the low Chandra background. The rest-frame ≈2.5-40 keV spectra are the first for optically faint (two of the three sources have I > 24) z > 4 AGNs. The z = 5.186 quasar is well fitted by a power-law model with photon index Γ = 1.8 ± 0.3, consistent with those of lower-redshift, unobscured AGNs. The other two AGNs have flatter effective X-ray photon indices (Γ ≈ 1.1-1.5), suggesting the presence of intrinsic absorption (provided their underlying X-ray continua are similar to those of lower redshift AGNs). It is possible that the flat X-ray continuum of the z = 4.424 AGN is partially related to its radio loudness. If the z = 4.137 AGN suffers from X-ray absorption, the implied column density is NH 2 × 10 23 cm-2.",

author = "C. Vignali and Bauer, {F. E.} and Alexander, {D. M.} and Brandt, {W. N.} and Hornschemeier, {A. E.} and Schneider, {D. P.} and Garmire, {G. P.}",

note = "Funding Information: This work would not have been possible without the support of the entire Chandra and ACIS teams. We particularly thank P. Broos and L. Townsley for data analysis software and charge transfer inefficiency correction support and G. Brunetti for useful discussions. We acknowledge the financial support of NASA grants NAS 8-38252 and NAS 8-01128 (G. P. G., PI), NSF CAREER award AST-9983783 (C. V., F. E. B., D. M. A., W. N. B.), CXC grant G02-3187A (F. E. B., D. M. A., W. N. B.), CXO grant PF2-30021 (A. E. H.), and NSF grant AST-9900703 (D. P. S.). C. V. also acknowledges partial support from ASI I/R/113/01 and Cofin-00-02-36.",

year = "2002",

month = dec,

day = "1",

doi = "10.1086/345751",

language = "English (US)",

volume = "580",

pages = "L105--L109",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2 II",

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TY - JOUR

T1 - The chandra deep field-north survey. XVI. The x-ray properties of moderate-luminosity active galaxies at z > 4

AU - Vignali, C.

AU - Bauer, F. E.

AU - Alexander, D. M.

AU - Brandt, W. N.

AU - Hornschemeier, A. E.

AU - Schneider, D. P.

AU - Garmire, G. P.

N1 - Funding Information: This work would not have been possible without the support of the entire Chandra and ACIS teams. We particularly thank P. Broos and L. Townsley for data analysis software and charge transfer inefficiency correction support and G. Brunetti for useful discussions. We acknowledge the financial support of NASA grants NAS 8-38252 and NAS 8-01128 (G. P. G., PI), NSF CAREER award AST-9983783 (C. V., F. E. B., D. M. A., W. N. B.), CXC grant G02-3187A (F. E. B., D. M. A., W. N. B.), CXO grant PF2-30021 (A. E. H.), and NSF grant AST-9900703 (D. P. S.). C. V. also acknowledges partial support from ASI I/R/113/01 and Cofin-00-02-36.

PY - 2002/12/1

Y1 - 2002/12/1

N2 - We present X-ray spectral analyses of the three z > 4 active galactic nuclei (AGNs) thus far spectroscopically identified in the Chandra Deep Field-North Survey, at redshifts of 5.186, 4.424, and 4.137. These analyses are made possible by the extremely deep exposure (≈2 Ms) and the low Chandra background. The rest-frame ≈2.5-40 keV spectra are the first for optically faint (two of the three sources have I > 24) z > 4 AGNs. The z = 5.186 quasar is well fitted by a power-law model with photon index Γ = 1.8 ± 0.3, consistent with those of lower-redshift, unobscured AGNs. The other two AGNs have flatter effective X-ray photon indices (Γ ≈ 1.1-1.5), suggesting the presence of intrinsic absorption (provided their underlying X-ray continua are similar to those of lower redshift AGNs). It is possible that the flat X-ray continuum of the z = 4.424 AGN is partially related to its radio loudness. If the z = 4.137 AGN suffers from X-ray absorption, the implied column density is NH 2 × 10 23 cm-2.

AB - We present X-ray spectral analyses of the three z > 4 active galactic nuclei (AGNs) thus far spectroscopically identified in the Chandra Deep Field-North Survey, at redshifts of 5.186, 4.424, and 4.137. These analyses are made possible by the extremely deep exposure (≈2 Ms) and the low Chandra background. The rest-frame ≈2.5-40 keV spectra are the first for optically faint (two of the three sources have I > 24) z > 4 AGNs. The z = 5.186 quasar is well fitted by a power-law model with photon index Γ = 1.8 ± 0.3, consistent with those of lower-redshift, unobscured AGNs. The other two AGNs have flatter effective X-ray photon indices (Γ ≈ 1.1-1.5), suggesting the presence of intrinsic absorption (provided their underlying X-ray continua are similar to those of lower redshift AGNs). It is possible that the flat X-ray continuum of the z = 4.424 AGN is partially related to its radio loudness. If the z = 4.137 AGN suffers from X-ray absorption, the implied column density is NH 2 × 10 23 cm-2.

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U2 - 10.1086/345751

DO - 10.1086/345751

M3 - Review article

AN - SCOPUS:0001288927

SN - 0004-637X

VL - 580

SP - L105-L109

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 II

ER -

The chandra deep field-north survey. XVI. The x-ray properties of moderate-luminosity active galaxies at z > 4

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