MIDIS: Quantifying the active galactic nucleus component of X-ray-detected galaxies

X-ray and infrared surveys provide efficient, and to some degree complementary, means of detecting and characterising active galactic nuclei (AGNs), with the infrared also providing an important probe of the host galaxies. To this end we combine the deepest X-ray survey from the Chandra Deep Field-South (CDF-S) ‘7-Ms’ survey with the deepest mid-infrared (5.6 μm) image from the JWST/MIRI Deep Imaging Survey (MIDIS) in the Hubble Ultra-Deep Field (HUDF) to study the infrared counterparts and point-source emission of 31 X-ray sources with a median, intrinsic, rest-frame X-ray luminosity of log 10 ( L Xc 0.5−7 keV ) = 42.04 ± 0.22 erg s −1 . The sample includes 24 AGNs with a redshift range, set by the X-ray detectability, of z ≃ 0.5−3, with the bulk of the sources lying at z ≃ 1−2, i.e. around the epoch of cosmic noon. Through a multi-wavelength morphological decomposition, employing three separate classifications (visual, parametric, and non-parametric), we separate (where present) the luminosity of the point-like AGN component from the remainder of the host-galaxy emission. The unprecedented mid-infrared sensitivity and imaging resolution of MIRI allows, in many cases, for the direct characterisation of point-like (i.e. unresolved) components in the galaxies’ emission. We establish a broad agreement between the three morphological classifications. At least 70% of the X-ray sources, including some classified as galaxies, show unresolved emission in the MIRI images, with the unresolved-to-total flux fraction at rest-frame 2 μm ranging from ∼0.2 to ∼0.9. At high X-ray luminosities (log 10 ( L Xc ) > 43 erg s −1 ), we derive a consistent rest-frame near-infrared 2 μm point-source luminosity to that derived for local AGNs, whilst at lower X-ray luminosities we identify an excess in the 2 μm emission compared to pre-JWST studies. We speculate that this offset may be driven by a combination of Compton-thick AGN components and nuclear starburst, merger-driven activity. Our observations highlight the complex nature of X-ray sources in the distant Universe and demonstrate the power of JWST/MIRI in quantifying their nuclear infrared emission.

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Journal
Astronomy and Astrophysics
Published
2025-10-28
DOI
https://doi.org/10.1051/0004-6361/202553779
Primary Topic
Galaxies: Formation, Evolution, Phenomena
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article
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article

MIDIS: Quantifying the active galactic nucleus component of X-ray-detected galaxies

Fabian Walter, M. Guêdel, A. Bik, Pascal Ray et al.
Astronomy and Astrophysics
Galaxies: Formation, Evolution, Phenomena
article

MIDIS: Quantifying the active galactic nucleus component of X-ray-detected galaxies

Fabian Walter, M. Guêdel, A. Bik, Pascal Ray, A. Alonso‐Herrero, Alvaro Labiano, Luca Costantin, L. Colina, Alejandro Crespo Gómez, Leindert Boogaard, Edoardo Iani, Ralf Greve, J. E. Ward, Pierluigi Rinaldi, Eckhard Bosman, Javier Álvarez-Márquez, M. García-Marín, G. Östlin, Jens Melinder, Thomas Henning, Steven Gillman, Danial Langeroodi, Florian Peißker, Jens Hjorth, Andreas Eckart, P. O. Lagage, G. Pablo Pérez-González, P. John Pye, V. Tuomo Tikkanen
article en

Abstract

X-ray and infrared surveys provide efficient, and to some degree complementary, means of detecting and characterising active galactic nuclei (AGNs), with the infrared also providing an important probe of the host galaxies. To this end we combine the deepest X-ray survey from the Chandra Deep Field-South (CDF-S) ‘7-Ms’ survey with the deepest mid-infrared (5.6 μm) image from the JWST/MIRI Deep Imaging Survey (MIDIS) in the Hubble Ultra-Deep Field (HUDF) to study the infrared counterparts and point-source emission of 31 X-ray sources with a median, intrinsic, rest-frame X-ray luminosity of log 10 ( L Xc 0.5−7 keV ) = 42.04 ± 0.22 erg s −1 . The sample includes 24 AGNs with a redshift range, set by the X-ray detectability, of z ≃ 0.5−3, with the bulk of the sources lying at z ≃ 1−2, i.e. around the epoch of cosmic noon. Through a multi-wavelength morphological decomposition, employing three separate classifications (visual, parametric, and non-parametric), we separate (where present) the luminosity of the point-like AGN component from the remainder of the host-galaxy emission. The unprecedented mid-infrared sensitivity and imaging resolution of MIRI allows, in many cases, for the direct characterisation of point-like (i.e. unresolved) components in the galaxies’ emission. We establish a broad agreement between the three morphological classifications. At least 70% of the X-ray sources, including some classified as galaxies, show unresolved emission in the MIRI images, with the unresolved-to-total flux fraction at rest-frame 2 μm ranging from ∼0.2 to ∼0.9. At high X-ray luminosities (log 10 ( L Xc ) > 43 erg s −1 ), we derive a consistent rest-frame near-infrared 2 μm point-source luminosity to that derived for local AGNs, whilst at lower X-ray luminosities we identify an excess in the 2 μm emission compared to pre-JWST studies. We speculate that this offset may be driven by a combination of Compton-thick AGN components and nuclear starburst, merger-driven activity. Our observations highlight the complex nature of X-ray sources in the distant Universe and demonstrate the power of JWST/MIRI in quantifying their nuclear infrared emission.

Astronomy and AstrophysicsVol. 704
Leiden University (NL), University of Copenhagen (DK), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), University of Vienna (AT), Dublin Institute For Advanced Studies (IE), Consejo Superior de Investigaciones Científicas (ES), University of Arizona (US), University of Leicester (GB), Délégation Paris 7 (FR), University of Groningen (NL), University of Cologne (DE), Durham University (GB), Université Paris Cité (FR), Heidelberg University (DE), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), European Space Agency (FR), Department of Space (IN), Astrophysique, Instrumentation et Modélisation (FR), Sorbonne Paris Cité (FR), Institute of Particle Physics (CA), European Centre for Space Applications and Telecommunications (GB), DAWN Center for Independent Living (US), Instituto de Física Teórica (ES), Schnörringen Telescope Science Institute (DE), CEA Paris-Saclay (FR), Centro de Astrobiología (ES), AlbaNova (SE), Astronomical Institute of the Slovak Academy of Sciences (SK), Heidelberg Institute for Theoretical Studies (DE)
National Aeronautics and Space Administration, Villum Fonden, Space Telescope Science Institute, Ministerio de Ciencia, Innovación y Universidades, European Commission, National Research Foundation, Deutsche Forschungsgemeinschaft, Danmarks Grundforskningsfond, Swedish National Space Agency, Nuclear Safety and Security Commission, Ministerio de Ciencia e Innovación, Science and Technology Facilities Council, European Regional Development Fund, Agencia Estatal de Investigación
Openalex Percentile: Top 78%
Galaxies: Formation, Evolution, Phenomena
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