The High Energy X-ray Probe (HEX-P): The Circum-nuclear Environment of Growing Supermassive Black Holes

HEX-P is a probe-class mission concept that will combine high spatial resolution X-ray imaging (<10 arcsec FWHM) and broad spectral coverage (0.2-80 keV) with an effective area superior to current facilities (including XMM-Newton and NuSTAR), enabling revolutionary new insights into a variety of important astrophysical problems. A key goal of modern astrophysical observatories is to understand the structure and geometry of the circum-nuclear environment surrounding growing supermassive black holes (aka Active Galactic Nuclei; AGN), and how that environment co-evolves with the encompassing host galaxy and central engine. In this poster, we will showcase a number of exciting prospects HEX-P holds in this regard for studying the dense surroundings of growing supermassive black holes in our cosmic backyard. Due to its uniquely sensitive and strictly simultaneous broadband X-ray coverage, HEX-P is ideally suited to provide a next-generation multi-epoch library of heavily obscured AGN spectroscopy to drive the development of physically-motivated models to describe the structure and dynamical nature of the circum-nuclear obscurer in exquisite detail. The considerably lower background and excellent angular resolution will be key to disentangle off-nuclear ultra-luminous X-ray sources from genuine heavily obscured AGN at some of the lowest unabsorbed X-ray luminosities currently known. In combination with the plethora of multi-wavelength next-generation all-sky surveys that are planned and coming online, complementary studies with HEX-P will be pivotal in deciphering the connection between the AGN obscurer and surrounding host galaxy in some of the highest column density and covering factor regimes known. The capabilities of HEX-P are hence ideally suited for overcoming present day modelling limitations, as well as completing the black hole accretion and host galaxy co-evolution censuses in the nearby Universe for the first time. More information on HEX-P, including the full team list, is available at hexp.org.