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

Gianolli, V. E.; Bianchi, S.; Kammoun, E.; Gnarini, A.; Marinucci, A.; Ursini, F.; Parra, M.; Tortosa, A.; De Rosa, A.; Kim, D. E.; Marin, F.; Matt, G.; Serafinelli, R.; Soffitta, P.; Tagliacozzo, D.; Di Gesu, L.; Done, C.; Marshall, H. L.; Middei, R.; Mikusincova, R.; Petrucci, P-O.; Ravi, S.; Svoboda, J.; Tombesi, F.

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 ∼4.6σ). 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.

Citation

Gianolli, V. E., Bianchi, S., Kammoun, E., Gnarini, A., Marinucci, A., Ursini, F., Parra, M., Tortosa, A., De Rosa, A., Kim, D. E., Marin, F., Matt, G., Serafinelli, R., Soffitta, P., Tagliacozzo, D., Di Gesu, L., Done, C., Marshall, H. L., Middei, R., Mikusincova, R., …Tombesi, F. (2024). A second view on the X-ray polarization of NGC 4151 with IXPE. Astronomy & Astrophysics, 691, Article A29. https://doi.org/10.1051/0004-6361/202451645

• Journal Article Type: Article
• Acceptance Date: Sep 6, 2024
• Online Publication Date: Oct 29, 2024
• Publication Date: 2024-11
• Deposit Date: Dec 2, 2024
• Publicly Available Date: Dec 2, 2024
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 691
• Article Number: A29
• DOI: https://doi.org/10.1051/0004-6361/202451645
• Public URL: https://durham-repository.worktribe.com/output/3197826