2004MNRAS.351L...9C

We report the discovery of a strong iron Kα line in the hard X-ray selected source CXOJ 123716.7+621733 in the Chandra Deep Field-North survey at z= 1.146. The analysis is made possible by the very deep exposure of ∼2 Ms and the low background of the Advanced CCD Imaging Spectrometer (ACIS). The line profile seems to be inconsistent with a narrow feature. The best-fitting solution is achieved with a broad line. Most of the flux in the broad component originates at energies below 6.4 keV with a shape similar to that expected from emission in the innermost regions of the accretion disc.