IXPE and

We report the third observation of the Seyfert-1.9 active galactic nucleus (AGN) MCG-05-23-16 with the Imaging X-ray Polarimetry Explorer (IXPE), together with optical spectropolarimetry obtained at the Very Large Telescope (VLT), and combined with archival near-ultraviolet, optical, and near-infrared polarimetric data. We detect no X-ray polarization in the 2–8 keV band, with a 99% confidence upper limit of ≤2.9%, which is further reduced to ≤2.5% when combined with the two previous IXPE observations of the same target. Monte Carlo simulations suggest that equatorial coronal models are disfavored if the AGN is indeed a type 1.9/2 AGN, while coronae coplanar to the accretion disk remain consistent if the source is less inclined than previously assumed. Data from VLT/FORS2 reveal a typical type 2 spectrum in total flux, a broad Hα line in polarized flux, and a polarization degree and angle that depend strongly on wavelength. The polarization angle rotates by nearly 70° across the optical band. Comparison with historical measurements confirms the long-term stability of the polarization spectrum and a ∼90° rotation in the near-ultraviolet. Interpreting the multiwavelength polarization relative to the AGN ionization axis indicates that the main obscurer is not a compact circumnuclear torus, but rather a distant kiloparsec-scale dust lane crossing the galaxy. This result implies that MCG-05-23-16 is, in fact, a type 1 AGN seen through foreground dust. The low X-ray column density becomes consistent with the absence of polarization, provided that the nuclear inclination is low.

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Publication Details

Journal
Springer Link (Chiba Institute of Technology)
Published
2026-03-03
DOI
https://doi.org/10.1051/0004-6361/202558176/pdf
Primary Topic
Astrophysical Phenomena and Observations
Type
article
Field-Weighted Citation Impact
0.00

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article

IXPE and

F. Ursini, Daniele Tagliacozzo, R. Middei, Nicole Cavero Rodriguez et al.
Springer Link (Chiba Institute of Technology)
Astrophysical Phenomena and Observations
article

IXPE and

F. Ursini, Daniele Tagliacozzo, R. Middei, Nicole Cavero Rodriguez, V. E. Gianolli, Andrea Marinucci, Jirí Svoboda, Alessandro Leonardo Lai, Ephraim Gau, Henric Krawczynski, Mitsuru Kokubo, Pierre-Olivier Petrucci, W. Peter Maksym, Kun Hu, Frédéric Marin, Damien Hutsemékers, Francesco Tombesi, Thibault Barnouin, Giorgio Matt, Stefano Bianchi, Herman Marshall, Roberto Serafinelli, Simonetta Puccetti
article en

Abstract

We report the third observation of the Seyfert-1.9 active galactic nucleus (AGN) MCG-05-23-16 with the Imaging X-ray Polarimetry Explorer (IXPE), together with optical spectropolarimetry obtained at the Very Large Telescope (VLT), and combined with archival near-ultraviolet, optical, and near-infrared polarimetric data. We detect no X-ray polarization in the 2–8 keV band, with a 99% confidence upper limit of ≤2.9%, which is further reduced to ≤2.5% when combined with the two previous IXPE observations of the same target. Monte Carlo simulations suggest that equatorial coronal models are disfavored if the AGN is indeed a type 1.9/2 AGN, while coronae coplanar to the accretion disk remain consistent if the source is less inclined than previously assumed. Data from VLT/FORS2 reveal a typical type 2 spectrum in total flux, a broad Hα line in polarized flux, and a polarization degree and angle that depend strongly on wavelength. The polarization angle rotates by nearly 70° across the optical band. Comparison with historical measurements confirms the long-term stability of the polarization spectrum and a ∼90° rotation in the near-ultraviolet. Interpreting the multiwavelength polarization relative to the AGN ionization axis indicates that the main obscurer is not a compact circumnuclear torus, but rather a distant kiloparsec-scale dust lane crossing the galaxy. This result implies that MCG-05-23-16 is, in fact, a type 1 AGN seen through foreground dust. The low X-ray column density becomes consistent with the absence of polarization, provided that the nuclear inclination is low.

Springer Link (Chiba Institute of Technology)
National Aeronautics and Space Administration, University of Leicester, Grantová Agentura České Republiky, Fonds De La Recherche Scientifique - FNRS, Centre National d’Etudes Spatiales, Nuclear Safety and Security Commission, Agenzia Spaziale Italiana, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, Istituto Nazionale di Fisica Nucleare, Agencia Nacional de Investigación y Desarrollo, Marshall Space Flight Center, Goddard Space Flight Center
Openalex Percentile: Top 62%
Astrophysical Phenomena and Observations
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