The NuSTAR Survey of Swift/BAT Sources

Launch of the first focusing hard X-ray telescope, the Nuclear Spectroscopic Telescope Array (NuSTAR), enabled studies of the local active galactic nuclei (AGN) to extend in the spectral window above 10 keV with unprecedented spatial resolution and two orders of magnitude higher sensitivity than any other instrument operating in that bandpass. As a part of its long-term Extragalactic Surveys program, NuSTAR will survey the nearby population of AGN detected at hard X-ray energies in the Swift/BAT all-sky survey. In the first two years of operation we surveyed ~100 Swift/BAT AGN, which we present here. A short 15-25 ks NuSTAR exposure of a source detected with the Swift/BAT instrument provides a sufficiently detailed hard X-ray spectrum to provide well-constrained model parameters for each one individually. This sample forms an atlas of the best hard X-ray spectra available to date for a substantial number of AGN. Assuming a range of spectral models, both phenomenological and physically motivated, we determine the distributions of spectral parameters, such as the spectral index, absorption column, reflection strength and iron line equivalent width. Here we discuss the implications for the local Seyfert 2 population and the limitations of the current results. We also highlight more detailed studies of particular AGN, and preliminary results on multiplicity and variability in the hard X-ray band.