We present a detailed spectropolarimetric study of the Sco-like Z-source simultaneously observed with the Imaging X-ray Polarimetry Explorer (and Nuclear Spectroscopic Telescope Array (νstar). During the observations was mainly found in the normal branch. A model-independent polarimetric analysis yields a polarisation degree of 1. 1% ± 0. 3% at a polarisation angle of 29 ± 7 in the 2--8, keV band, with a ∼4. 1σ confidence level significance. No variability of polarisation in time and flux has been observed, while an energy-resolved analysis shows a complex dependence of polarisation on energy, as confirmed by a spectropolarimetric analysis. Spectral modelling reveals a dominant disc blackbody component and a Comptonising emitting region, with evidence of a broad iron line associated with a reflection component. Spectropolarimetric fits suggest differing polarisation properties for the disc and Comptonised components, and slightly favour a spreading layer geometry. The polarisation of the Comptonised component exceeds the theoretical expectations but is in line with the results for other Z-sources with similar inclinations. A study of the reflection's polarisation is also reported, with the polarisation degree ranging around 10% depending on the assumptions. Despite GX 349+2's classification as a Sco-like source, these polarimetric results align more closely with the Cyg-like system GX 340+0 of similar inclination. This indicates that polarisation is primarily governed by accretion state and orbital inclination, rather than by the subclass to which the source belongs.
Monaca et al. (Thu,) studied this question.