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

Abstract

We report on the second observing program of the active galactic nucleus NGC 4151 with simultaneous Imaging X-ray Polarimetry Explorer (IXPE; {\sim}750 ks), NuSTAR ({\sim}60 ks), XMM-Newton ({\sim}75 ks), and NICER ({\sim}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 is 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 {\pm} 1.3 percent and angle Ψ = 77° {\pm} 8° east of north (68 percent confidence level) are 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 {\pm} 0.9 percent and Ψ = 81° {\pm} 6° (with detection significance {\sim}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° {\pm} 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, rather pointing to scattering from some kind of mirror.

9 pages, 8 figures, 3 tables. Accepted to Astronomy & Astrophysics

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• Investigating the interplay between the coronal properties and the hard X-ray variability of active galactic nuclei with NuSTAR
• The polarized spectral energy distribution of NGC 4151
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Cited by in corpus (8)

• X-ray polarization from accretion disk winds
• X-ray linear polarization prediction in Black-Hole binaries and Active Galactic Nuclei and its measurements by IXPE
• X-ray polarization in radio-quiet AGN: Insights from the wedge corona model using Monte Carlo simulations
• A possible two-fold scenario for the disc-corona of the luminous AGN 1H 0419--577: a high-density disc or a warm corona
• Detection and Characterization of Quasi-Periodic Oscillations in Seyfert Galaxy NGC 4151
• Polarization Signatures of Quasi-Periodic Oscillations in Simulated Tilted, Truncated Disks
• On the Relation between the Inclination Angle of the Accretion Disk and the Broad-line Region in Active Galactic Nuclei
• X-ray polarization observations of NGC 2110 with IXPE