The Chandra Deep Field–North Survey and the cosmic X–ray background

Chandra has performed a 1.4 Ms survey centred on the Hubble Deep Field–North (HDF–N), probing the X–ray Universe 55–550 times deeper than was possible with pre–Chandra missions. We describe the detected point and extended X–ray sources and discuss their overall multi–wavelength (optical, infrared, submillimetre and radio) properties. Special attention is paid to the HDF–N X–ray sources, luminous infrared starburst galaxies, optically faint X–ray sources and high–to–extreme redshift active galactic nuclei. We also describe how stacking analyses have been used to probe the average X–ray–emission properties of normal and starburst galaxies at cosmologically interesting distances. Finally, we discuss plans to extend the survey and argue that a 5–10 Ms Chandra survey would lay key groundwork for future missions such as XEUS and Generation–X.