A second view on the X-ray polarization of NGC 4151 with IXPE

We report on the second observing program of the active galactic nucleus NGC 4151 with simultaneous Imaging X-ray Polarimetry Explorer (IXPE; 750 ks), NuSTAR (∼60 ks), XMM-Newton (∼75 ks), and NICER (∼65 ks) pointings. NGC 4151 is the first Type-1 radio-quiet Seyfert galaxy with constrained polarization properties for the X-ray corona. Despite the lower flux state in which the source was re-observed and the resulting higher contribution of the constant reflection component in the IXPE energy band, our results are in agreement with the first detection. From polarimetric analysis, a polarization degree Π = 4.7 ± 1.3% and polarization angle Ψ = 77° ± 8° east of north (68% c.l.) were derived in the 2.0–8.0 keV energy range. Combining the two observations leads to polarization properties that are more constrained than those of the individual detections, showing Π = 4.5 ± 0.9% and Ψ = 81° ± 6° (with a detection significance of ∼4.6 σ ). The observed polarization angle aligns very well with the radio emission in this source, supporting, together with the significant polarization degree, a slab or wedge geometry for the X-ray corona. However, a switch in the polarization angle at low energies (37° ±7° in the 2–3.5 keV bin) suggests the presence of another component. When it is included in the spectro-polarimetric fit, a high polarization degree disfavors an interpretation in terms of a leakage through the absorbers, instead pointing to scattering from some kind of mirror.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2024-09-30
DOI
https://doi.org/10.1051/0004-6361/202451645
Citations
17
Primary Topic
Astrophysical Phenomena and Observations
Type
article
Field-Weighted Citation Impact
5.64

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article

A second view on the X-ray polarization of NGC 4151 with IXPE

Chris Done, Jiří Svoboda, L. Di Gesu, Dawoon E. Kim et al.
17 citations
Astronomy and Astrophysics
Astrophysical Phenomena and Observations
5.64
article

A second view on the X-ray polarization of NGC 4151 with IXPE

Chris Done, Jiří Svoboda, L. Di Gesu, Dawoon E. Kim, A. Tortosa, R. Mikusincova, F. Ursini, G. Matt, S. Bianchi, Alessandra De Rosa, Francesco Tombesi, Daniele Tagliacozzo, Maxime Parra, Andrea Gnarini, Elias Kammoun, P. Soffitta, H. L. Marshall, Andrea Marinucci, R. Middei, V. E. Gianolli, Roberto Serafinelli, Frédéric Marin, Swati Ravi, P-O Petrucci
article en
17 citations

Abstract

We report on the second observing program of the active galactic nucleus NGC 4151 with simultaneous Imaging X-ray Polarimetry Explorer (IXPE; 750 ks), NuSTAR (∼60 ks), XMM-Newton (∼75 ks), and NICER (∼65 ks) pointings. NGC 4151 is the first Type-1 radio-quiet Seyfert galaxy with constrained polarization properties for the X-ray corona. Despite the lower flux state in which the source was re-observed and the resulting higher contribution of the constant reflection component in the IXPE energy band, our results are in agreement with the first detection. From polarimetric analysis, a polarization degree Π = 4.7 ± 1.3% and polarization angle Ψ = 77° ± 8° east of north (68% c.l.) were derived in the 2.0–8.0 keV energy range. Combining the two observations leads to polarization properties that are more constrained than those of the individual detections, showing Π = 4.5 ± 0.9% and Ψ = 81° ± 6° (with a detection significance of ∼4.6 σ ). The observed polarization angle aligns very well with the radio emission in this source, supporting, together with the significant polarization degree, a slab or wedge geometry for the X-ray corona. However, a switch in the polarization angle at low energies (37° ±7° in the 2–3.5 keV bin) suggests the presence of another component. When it is included in the spectro-polarimetric fit, a high polarization degree disfavors an interpretation in terms of a leakage through the absorbers, instead pointing to scattering from some kind of mirror.

Astronomy and AstrophysicsVol. 691
University of Rome Tor Vergata (IT), Roma Tre University (IT), Centre National de la Recherche Scientifique (FR), Durham University (GB), Astronomical Observatory of Rome (IT), Czech Academy of Sciences, Astronomical Institute (CZ), Agenzia Spaziale Italiana (IT), Japan Aerospace Exploration Agency (JP), Observatoire astronomique de Strasbourg (FR), Kavli Institute for Particle Astrophysics and Cosmology (US), Institute for Space Astrophysics and Planetology (IT), Institut de Planétologie et d'Astrophysique de Grenoble (FR), Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata (IT), Institute of Space and Astronautical Science (JP), Astronomical Observatory (RS), Massachusetts Institute of Technology (US), University of Maryland, College Park (US), Université de Strasbourg (FR), Sapienza University of Rome (IT), National Institute for Astrophysics (IT), Université Grenoble Alpes (FR)
National Aeronautics and Space Administration, Agenzia Spaziale Italiana, Istituto Nazionale di Astrofisica, Istituto Nazionale di Fisica Nucleare, Marshall Space Flight Center, Goddard Space Flight Center
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