The NuSTAR Serendipitous Survey

A great breakthrough in studying the cosmic X-ray background (CXB) population is the Nuclear Spectroscopic Telescope Array (NuSTAR), the first focusing X-ray observatory with high sensitivity at > 10 keV. Here we present results from the NuSTAR serendipitous survey, the largest area (~7 deg²) component of the NuSTAR extragalactic survey programme. The source statistics are relatively good for a high energy X-ray survey, with ~150 detections and ~100 spectroscopically identified sources to-date. Studying the X-ray emission at > 10 keV, where X-rays from the central black hole are relatively unabsorbed, allows intrinsic properties such as column densities and luminosities to be well constrained. The X-ray analysis is supplemented by broad-band UV to mid-IR spectral energy distribution (SED) analyses. The dominant source population sampled by the NuSTAR serendipitous survey is quasars with L(10-40)keV > 10⁴⁴ erg/s. This population is broadly similar to the population of nearby high-energy selected AGNs sampled by Swift/BAT, but scaled up in luminosity and mass.