Extragalactic Surveys with NuSTAR

The Nuclear Spectroscopic Telescope Array (NuSTAR), launched in June 2012, is opening the high energy X-ray sky for sensitive study for the first time. Soft X-ray telescopes like Chandra and XMM-Newton have peered deep into the X-ray universe at low energies and have resolved much of the X-ray background below a few keV. However, extrapolating such work to higher energies indicates that a significant population of heavily-obscured AGN remain undetected in the soft X-rays, but should be detectable in the hard X-ray band. By focusing X-rays at higher energy, up to 79 keV, NuSTAR will study the X-ray background at its 30 keV peak. The NuSTAR mission baselines three nested extragalactic surveys, a very deep 200 ks), pencil-beam survey of the Extended Chandra Deep Field-South (ECDFS) field, a moderate depth 50 ks) survey of the COSMOS field, and a shallow 10 ks) survey of 100 bright Swift/BAT AGN. We discuss plans, predictions and early results of the ECDFS and COSMOS programs. Discussion of the Swift/BAT program is presented in the companion poster by T.-N. Lu.