We report on the second observation of the radio-quiet active galactic nucleus (AGN) MCG-05-23-16 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation started on 2022 November 6 for a net observing time of 640 ks, and was partly simultaneous with NuSTAR (86 ks). After combining these data with those obtained in the first IXPE pointing on May 2022 (simultaneous with XMM-Newton and NuSTAR) we find a 2–8 keV polarization degree Π = 1.6 ± 0.7 (at 68 per cent confidence level), which corresponds to an upper limit Π = 3.2 per cent (at 99 per cent confidence level). We then compare the polarization results with Monte Carlo simulations obtained with the monk code, with which different coronal geometries have been explored (spherical lamppost, conical, slab and wedge). Furthermore, the allowed range of inclination angles is found for each geometry. If the best fit inclination value from a spectroscopic analysis is considered, a cone-shaped corona along the disc axis is disfavoured.

We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy NGC 4151. The source has been observed with the Imaging X-ray Polarimetry Explorer (IXPE) for 700 ks, complemented with simultaneous XMM-Newton (50 ks) and NuSTAR (100 ks) pointings. A polarization degree Π = 4.9 ± 1.1% and angle Ψ = 86○ ± 7○ east of north (68% confidence level) are measured in the 2–8 keV energy range. The spectro-polarimetric analysis shows that the polarization could be entirely due to reflection. Given the low reflection flux in the IXPE band, this requires however a reflection with a very large (>38%) polarization degree. Assuming more reasonable values, a polarization degree of the hot corona ranging from ∼4 to ∼8% is found. The observed polarization degree excludes a ‘spherical’ lamppost geometry for the corona, suggesting instead a slab-like geometry, possibly a wedge, as determined via Monte Carlo simulations. This is further confirmed by the X-ray polarization angle, which coincides with the direction of the extended radio emission in this source, supposed to match the disc axis. NGC 4151 is the first AGN with an X-ray polarization measure for the corona, illustrating the capabilities of X-ray polarimetry and IXPE in unveiling its geometry.

We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy IC 4329A. The Imaging X-ray Polarimetry Explorer (IXPE) observed the source for ∼500 ks, supported by XMM-Newton (∼60 ks) and NuSTAR (∼80 ks) exposures. We detect polarisation in the 2–8 keV band with 2.97σ confidence. We report a polarisation degree of 3.3 ± 1.1 per cent and a polarisation angle of 78○ ± 10○ (errors are 1σ confidence). The X-ray polarisation is consistent with being aligned with the radio jet, albeit partially due to large uncertainties on the radio position angle. We jointly fit the spectra from the three observatories to constrain the presence of a relativistic reflection component. From this, we obtain constraints on the inclination angle to the inner disc (<39○ at 99 per cent confidence) and the disc inner radius (<11 gravitational radii at 99 per cent confidence), although we note that modelling systematics in practice add to the quoted statistical error. Our spectro-polarimetric modelling indicates that the 2–8 keV polarisation is consistent with being dominated by emission directly observed from the X-ray corona, but the polarisation of the reflection component is completely unconstrained. Our constraints on viewer inclination and polarisation degree tentatively favour more asymmetric, possibly out-flowing, coronal geometries that produce more highly polarised emission, but the coronal geometry is unconstrained at the 3σ level.