Very high redshift X-ray-selected active galactic nuclei in the Chandra Deep Field-North

A. J. Barger, L. L. Cowie, P. Capak, D. M. Alexander, F. E. Bauer, W. N. Brandt, G. P. Garmire, A. E. Hornschemeier

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Abstract

Deep Chandra X-ray exposures provide an efficient route for locating optically faint active galactic nuclei (AGNs) at high redshifts. We use deep multicolor optical data to search for z > 5 AGNs in the 2 Ms X-ray exposure of the Chandra Deep Field-North. Of the 423 X-ray sources bright enough (z′ < 25.2) for a color-color analysis, at most one lies at z = 5-6, and none at z > 6. The one z > 5 object is spectroscopically confirmed at z = 5.19. Only 31 of the 77 sources with z′ > 25.2 are undetected in the B or V bands at the 2 σ level and could lie at z > 5. There are too few moderate-luminosity AGNs at z = 5-6.5 to ionize the intergalactic medium.

Original languageEnglish (US)
Pages (from-to)L61-L64
JournalAstrophysical Journal
Volume584
Issue number2 II
DOIs
StatePublished - Feb 20 2003

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Barger, A. J., Cowie, L. L., Capak, P., Alexander, D. M., Bauer, F. E., Brandt, W. N., Garmire, G. P., & Hornschemeier, A. E. (2003). Very high redshift X-ray-selected active galactic nuclei in the Chandra Deep Field-North. Astrophysical Journal, 584(2 II), L61-L64. https://doi.org/10.1086/368407