Exploratory Chandra observations of the highest-redshift quasars

X-rays from the dawn of the modern universe

C. Vignali, W. N. Brandt, Xiaohui Fan, J. E. Gunn, S. Kaspi, D. P. Schneider, Michael A. Strauss

Research output: Contribution to journalArticle

46 Citations (Scopus)

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 J160501.21-011220.0, 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 αox) with those of lower-redshift samples indicates that the Chandra quasars are X-ray fainter by a factor of ≈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.

Original languageEnglish (US)
Pages (from-to)2143-2155
Number of pages13
JournalAstronomical Journal
Volume122
Issue number5
DOIs
StatePublished - Nov 2001
Externally publishedYes

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quasars
universe
x rays
Constellation-X
observatory
radio
spectral energy distribution
prediction
gas
observatories
energy
galaxies

Keywords

  • Galaxies: active
  • Galaxies: nuclei
  • Quasars: general
  • X-rays

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Vignali, C., Brandt, W. N., Fan, X., Gunn, J. E., Kaspi, S., Schneider, D. P., & Strauss, M. A. (2001). Exploratory Chandra observations of the highest-redshift quasars: X-rays from the dawn of the modern universe. Astronomical Journal, 122(5), 2143-2155. https://doi.org/10.1086/323712

Exploratory Chandra observations of the highest-redshift quasars : X-rays from the dawn of the modern universe. / Vignali, C.; Brandt, W. N.; Fan, Xiaohui; Gunn, J. E.; Kaspi, S.; Schneider, D. P.; Strauss, Michael A.

In: Astronomical Journal, Vol. 122, No. 5, 11.2001, p. 2143-2155.

Research output: Contribution to journalArticle

Vignali, C, Brandt, WN, Fan, X, Gunn, JE, Kaspi, S, Schneider, DP & Strauss, MA 2001, 'Exploratory Chandra observations of the highest-redshift quasars: X-rays from the dawn of the modern universe', Astronomical Journal, vol. 122, no. 5, pp. 2143-2155. https://doi.org/10.1086/323712
Vignali, C. ; Brandt, W. N. ; Fan, Xiaohui ; Gunn, J. E. ; Kaspi, S. ; Schneider, D. P. ; Strauss, Michael A. / Exploratory Chandra observations of the highest-redshift quasars : X-rays from the dawn of the modern universe. In: Astronomical Journal. 2001 ; Vol. 122, No. 5. pp. 2143-2155.
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AB - 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 J160501.21-011220.0, 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 αox) with those of lower-redshift samples indicates that the Chandra quasars are X-ray fainter by a factor of ≈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.

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