XRISM Resolves the Circum-nuclear Environment of NGC 4945
Peter G. Boorman, Poshak Gandhi, Yoshihiro Ueda, Bert Vander Meulen, Kanta Fujiwara, Aoi Nakano, Johannes Buchner, Claudio Ricci, Kirpal Nandra, Daniel Stern, Almudena Alonso Herrero, Carolina Andonie, Franz E. Bauer, Stefano Bianchi, Murray Brightman, Francesca Civano, Richard I. Davies, Gulab Dewangan, Georgios Dimopoulos, Ismael García-Bernete, Santiago García-Burillo, Sebastian F. Hönig, Nancy A. Levenson, Andrea Merloni, Yuya Nakatani, Hirofumi Noda, Shoji Ogawa, Chris Packham, Simonetta Puccetti, Cristina Ramos Almeida, Marko Stalevski, Yuichi Terashima, Martin Ward, Satoshi Yamada
University of Southampton · University of Southampton · Kyoto University · ESTEC · Kyoto University · Kyoto University · MPE · Peking University · MPE · JPL · CSIC-INTA · MPE · Universidad de Tarapacá · Università degli Studi Roma Tre · Caltech · NASA Goddard Code 660 · MPE · IUCAA · NASA Goddard Code 662 · CSIC-INTA · OAN-IGN · University of Southampton · STScI · MPE · Kyoto University · Astronomical Institute, Tohoku University · Research Institute for Science & Technology, Tokyo University of Science · National Astronomical Observatory of Japan · ASI · Universidad de La Laguna · Universiteit Gent · Ehime University · Durham University · Astronomical Institute, Tohoku University
astro-ph.GA
Submitted: 2026-08-03
Comments: Submitted to A&A Letters. Comments welcome
Code: https://github.com/BertVdM/xskirtor
License: http://creativecommons.org/licenses/by-nc-sa/4.0/
The gist: Compton-thick Active Galactic Nuclei (AGN) represent one of the most elusive phases of massive black hole growth, yet are expected to contribute substantially to the Cosmic X-ray Background and the
Terminology
Abstract
Compton-thick Active Galactic Nuclei (AGN) represent one of the most elusive phases of massive black hole growth, yet are expected to contribute substantially to the Cosmic X-ray Background and the integrated growth of massive black holes. NGC 4945 is the closest Compton-thick AGN and amongst the brightest AGN in the hard X-ray sky, making it an important benchmark for more distant Compton-thick AGN. We present the first high-resolution X-ray spectral analysis of NGC 4945 using XRISM/Resolve. The entire 4-15 keV Resolve spectrum, including a strong Fe K alpha doublet and weak Compton Shoulder, is well described by a de-coupled dual-obscurer model. The model features a low-covering-factor Compton-thick primary obscurer intersecting the line-of-sight that permits the rapidly variable, direct transmitted coronal continuum to dominate above 10 keV. A Compton-thin secondary reprocessor with a high covering factor dominates the reprocessed emission between about 4-10 keV. Assuming that virial motion accounts for line broadening, the secondary reprocessor can exist at about 0.12 pc, and could help explain the weak high-ionisation optical and infrared emission lines observed in NGC 4945. If such obscuration geometries are common among more distant and/or fainter Compton-thick AGN, our results suggest that simpler coupled X-ray spectral modelling could substantially over-estimate Compton-thick covering factors and under-estimate intrinsic X-ray luminosities.
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