High Polarization and Complex Accretion Wind Structure in 4U 1700−37

We present a spectro-polarimetric analysis of the wind-accreting high-mass X-ray binary 4U 1700−37 with the Imaging X-ray Polarimetry Explorer (IXPE). Using the hardness–intensity diagram (HID), we divide the observations into three states: a high-soft state (HR 1), a medium state (HR 2), and a low-hard state (HR 3). HR 1 and HR 3 exhibit high polarization degree (PD) values of 9.6 ± 1.5 % and 22.4 ± 4.3 %, respectively, while HR 2 exhibits a lower PD of 7.2 ± 1.6 %. Using a phenomenological triple power-law model further reveals a highly polarized, unobscured component in HR 1 (PD = 41.5 ± 12.3 %), which may originate from the polar region of the neutron star. The wind-reprocessed components in HR 1 and HR 3 both show PD exceeding 15 %, which may arise from the superposition or interaction of disk-wind scattering and neutron star radiation whose polarization direction is aligned with it, or be related to symmetry breaking. The decline in PD in HR 2, together with the 30○–40○ differences in polarization angle (PA) between states, may imply the disruption of a transient disk and a transition in accretion mode. In addition, the 99 % confidence upper limit on PD during the mid-eclipse phase is ~10 %, lower than the predictions from simple stellar wind models, indicating a more complex wind geometry.