Taking Hard X-ray Spectroscopy from the Local Universe out to the Cosmic Noon

The nature of obscuring structures hiding the central engine of obscured active galactic nuclei (AGN) remains unclear. Broadband X-ray spectroscopy gives us unique insight into the anatomy of obscured AGN in the local universe as hard X-rays punch through even heavy obscuration, enabling us to study both the X-ray source and the properties of the obscuring matter. Much has been learned from hundreds of observations of nearby AGN taken over the first 10 years of NuSTAR, but less so for typical AGN at high redshift closer to the Cosmic Noon, when AGN feedback was more important for galaxy evolution and AGN obscuration may have been structured very differently. This poster presents the principles of deriving obscuration geometry constraints via hard X-ray spectroscopy and real constraints on the geometry of the obscuring structures based on a large sample of nearby obscured AGN observed with NuSTAR. Finally, preliminary results on the strength of reprocessing spectral features are shown for a small sample of high-luminosity, intermediate-redshift (z~0.5) quasars recently observed with long XMM-Newton and NuSTAR exposures. Covering the hard X-ray rest-frame band that includes the critical spectral features at high redshift (z~3), Athena promises to open up a unique window onto the obscuring structures in powerful AGN at Cosmic Noon.