X-ray polarization of the Compton-thin Seyfert galaxy NGC 5506 with IXPE

We report on the observation of the Compton-thin Seyfert galaxy NGC 5506 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation, with a net observing time of 975 ks, was partly simultaneous with NuSTAR (52 ks) and XMM-Newton (37 ks). Using a simple baseline model with IXPE data only, we find an upper limit on the 2--8 keV polarization fraction at the 99% confidence level: Π<3.1%. We then performed a spectropolarimetric analysis combining data from the three X-ray observatories. While pure spectral modeling confirms the presence of both relativistic and cold distant reflection, in addition to the primary continuum power law, their contributions lead to somewhat different constraints on the coronal Π, depending on the specific assumptions. We also performed Monte Carlo simulations with the radiative transfer code MONK, exploring various coronal geometries. Comparing these results with the IXPE data, and assuming a radially extended corona, as suggested by previous observations of similar sources, the corresponding polarization upper limits require inclination angles below 40°.