Sensitive X-ray observations have revealed that most growing supermassive black holes (aka Active Galactic Nuclei - AGN) are obscured by large columns of gas, with their broadband spectra peaking in the X-ray and IR regimes. As such, these regimes carry complementary information about the AGN intrinsic and reprocessing structures. In this talk, I will discuss multiple techniques of selection and characterisation of obscured AGN, including new results based upon an X-ray 'Baldwin Effect' in heavily obscured sources. This study indicates that simplistic modelling of reprocessed X-ray spectra in highly obscured AGN underpredicts their growth rates, and thus a ‘representative' census of the entire AGN population is essential. To tackle this issue, we have begun the NuSTAR Local AGN N(H) Distribution Survey (NuLANDS) — a > 4 Ms legacy survey of AGN currently underway with NuSTAR, XMM-Newton and the Neil Gehrels Swift Observatory. The novel IR selection and optical classification of the sample ensures we are unbiased by X-ray obscuration up to the highest columns of material. I will present the preliminary results from the survey, most notably the indication that > 30% of all AGN in the local Universe are heavily obscured, and that hard X-ray selection alone preferentially selects less-obscured AGN. These preliminary NuLANDS results thus mark a major step towards completing the local census of accretion activity amongst AGN, as well as understanding the role obscuration plays in their evolution.
Sporilov, mistnost 101