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Front. Astron. Space Sci.
Sec. Extragalactic Astronomy
Volume 11 - 2024 | doi: 10.3389/fspas.2024.1335459

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

 Peter Boorman1* N Torres-Albà2 A Annuar3 S Marchesi2, 4 R Pfeifle5 D Stern1, 6  Francesca M. Civano5 M Baloković7, 8  Johannes Buchner9 C Ricci10, 11 D M. Alexander12  William N. Brandt13, 14, 15 M Brightman1 C T. Chen16, 17 S Creech18 P Gandhi19  Javier A. García1, 5 F Harrison1 R Hickox20  Elias Kammoun21, 22 S Lamassa23  G Lanzuisi4  Lea Marcotulli7, 8  K Madsen5 G Matt21  G Matzeu24 E Nardini22  Joanna Piotrowska1 A Pizzetti2  Simonetta Puccetti25 D Sicilian26 R Silver5 D J. Walton27  D R. Wilkins28 X Zhao29
  • 1California Institute of Technology, United States
  • 2Department of Physics and Astronomy, Clemson University, United States
  • 3National University of Malaysia, Malaysia
  • 4Osservatorio di Astrofisica e Scienza dello Spazio di Bologna (INAF), Italy
  • 5Goddard Space Flight Center, National Aeronautics and Space Administration, United States
  • 6Jet Propulsion Laboratory, California Institute of Technology, United States
  • 7Center for Astronomy and Astrophysics, Yale University, United States
  • 8Department of Physics, Faculty of Arts and Sciences, Yale University, United States
  • 9Max Planck Institute for Extraterrestrial Physics, Germany
  • 10Astronomy Nucleus, Faculty of Engineering and Sciences, Diego Portales University, Chile
  • 11The Kavli Institute for Astronomy and Astrophysics, School of Physics, Faculty of Science, Peking University, China
  • 12Centre for Extragalactic Astronomy, Durham University, United Kingdom
  • 13Department of Astronomy and Astrophysics, Eberly College of Science, The Pennsylvania State University, United States
  • 14Institute for Gravitation and the Cosmos, The Pennsylvania State University, United States
  • 15Department of Physics and Astronomy, School of Arts and Sciences, University of Pennsylvania, United States
  • 16National Space Science and Technology Center (NASA), United States
  • 17Marshall Space Flight Center, National Aeronautics and Space Administration, United States
  • 18Department of Physics & Astronomy, College of Science, The University of Utah, United States
  • 19Department of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Southampton, United Kingdom
  • 20Department of Physics and Astronomy, Dartmouth College, United States
  • 21Department of Mathematics and Physics, Roma Tre University, Italy
  • 22Osservatorio Astrofisico di Arcetri (INAF), Italy
  • 23Space Telescope Science Institute (NASA), United States
  • 24European Space Astronomy Centre (ESAC), Spain
  • 25Italian Space Agency (ASI), Italy
  • 26Department of Physics, Miami University, United States
  • 27Centre for Astrophysics Research, School of Physics Astronomy and Mathematics, University of Hertfordshire, United Kingdom
  • 28Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, United States
  • 29Center for Astrophysics, Harvard University, United States

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Ever since the discovery of the first Active Galactic Nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures of some level of obscuration in their X-ray spectra. But despite more than six decades of effort, substantial open questions remain: How does the accretion power impact the structure of the circum-nuclear obscurer? What are the dynamical properties of the obscurer? Can dense circum-nuclear obscuration exist around intrinsically weak AGN? How many intermediate mass black holes occupy the centers of dwarf galaxies? In this paper, we showcase a number of next-generation prospects attainable with the High Energy X-ray Probe (HEX-P 1 ) to contribute towards solving these questions in the 2030s.The uniquely broad (0.2 -80 keV) and strictly simultaneous X-ray passband of HEX-P makes it ideally suited for studying the temporal co-evolution between the central engine and circumnuclear obscurer. Improved sensitivities and reduced background will enable the development of spectroscopic models complemented by current and future multi-wavelength observations. We show that the angular resolution of HEX-P both below and above 10 keV will enable the discovery and confirmation of accreting massive black holes at both low accretion power and low black hole masses even when concealed by thick obscuration. In combination with other next-generation observations of the dusty hearts of nearby galaxies, HEX-P will be pivotal in paving the way towards a complete picture of black hole growth and galaxy co-evolution.

Keywords: x-ray, AGN, obscuration, black hole, Galaxies, Compton-thick, High energy, Spectral modelling

Received: 08 Nov 2023; Accepted: 21 Feb 2024.

Copyright: © 2024 Boorman, Torres-Albà, Annuar, Marchesi, Pfeifle, Stern, Civano, Baloković, Buchner, Ricci, Alexander, Brandt, Brightman, Chen, Creech, Gandhi, García, Harrison, Hickox, Kammoun, Lamassa, Lanzuisi, Marcotulli, Madsen, Matt, Matzeu, Nardini, Piotrowska, Pizzetti, Puccetti, Sicilian, Silver, Walton, Wilkins and Zhao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Peter Boorman, California Institute of Technology, Pasadena, United States