X-ray and optical polarization aligned with the radio jet ejecta in GX 339-4

We present the first X-ray polarization measurements of GX 339-4. IXPE observed this source twice during its 2023-2024 outburst, once in the soft-intermediate state and again during a soft state. The observation taken during the intermediate state shows significant (4\sigma) polarization degree P = 1.3\% \pm 0.3\% and polarization angle... Show more