Desde Marzo 07, 2018 13:15 hasta Marzo 07, 2018 13:45
En Seminar Room
Accretion of material onto supermassive black holes powers the high-energy X-ray emission from active galactic nuclei (AGN) - most of which are predicted to be obscured by thick layers of gas and dust. The NuSTAR Local AGN N_H Distribution Survey (NuLANDS) is one of the largest (1 Ms) legacy surveys of AGN currently underway with the X-ray satellites NuSTAR, XMM-Newton and the Neil Gehrels Swift Observatory. Due to the isotropic (far-infrared) selection capable of selecting sources irrespective of X-ray obscuration, and sensitive optical spectroscopic classifications, NuLANDS will provide a representative sampling of obscuring column density (N_H), transforming our understanding of AGN obscuration in the local Universe. Furthermore, due to the unprecedented sensitivity of NuSTAR in high energy X-rays, NuLANDS is capable of robustly inferring the column densities of heavily obscured AGN with broadband X-ray spectral modelling. In this talk, I will review the pros and cons of AGN selection strategies from radio to X-rays. I will then present the new and growing sample of heavily obscured AGN in NuLANDS, each previously undetected after > 8 years of contiguous exposure with the Swift/Burst Alert Telescope, due to their extreme nuclear obscuration. Finally, I will present the ultimate goal of NuLANDS: to construct a representative understanding of obscuration and accretion rates amongst AGN in the local Universe.