标题： X射线偏振研究中子星低质量X射线双星GX 349+2 显示英文标题

标题： X-ray polarization study of the neutron star low-mass X-ray binary GX 349+2

摘要： 我们报告了使用成像X射线偏振探测器（IXPE）对中子星（NS）低质量X射线双星（LMXB）Z源GX 349+2进行的首次X射线偏振测量结果。我们发现X射线源的偏振度为PD = 1.1 +/- 0.3％（1-σ误差），偏振角为PA = 32 +/- 6度（1-σ误差）。同时进行的核光谱望远镜阵列（NuSTAR）观测显示，在我们的IXPE观测期间，该源在Z轨的正常分支（NB）、爆发分支（FB）和软顶点（SA）之间发生了转变。X射线光谱偏振测量结果表明，该源的几何结构包括吸积盘分量、代表中子星表面辐射的黑体以及康普顿化分量。我们根据光谱偏振测量结果讨论了Z源的吸积几何结构。 显示英文摘要

摘要： We report the first X-ray polarimetric results of the neutron star (NS) low-mass X-ray binary (LMXB) Z-source GX 349+2 using the Imaging X-ray Polarimetry Explorer (IXPE). We discovered that the X-ray source was polarized at PD = 1.1 +/- 0.3% (1-sigma errors) with a polarization angle of PA = 32 +/- 6 degree (1-sigma errors). Simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) observations show that the source transitioned through the normal branch (NB), flaring branch (FB), and soft apex (SA) of the Z-track during our IXPE observations. The X-ray spectro-polarimetry results suggest a source geometry comprising an accretion disk component, a blackbody representing the emission from the NS surface, and a Comptonized component. We discuss the accretion geometry of the Z source in light of the spectro-polarimetric results.