标题： 利用更深的IXPE观测分析蟹状星云X射线偏振 显示英文标题

标题： Analysis of Crab X-ray Polarization using Deeper IXPE Observations

摘要： 我们利用IXPE数据进行了蟹状星云脉冲星的X射线偏振测量，总曝光时间为300 ks，是2022年发现论文中曝光时间的三倍。 偏振在三倍更多的脉冲相位区间内被检测到，在主脉冲中显示出一个S形的$+40^\circ$偏振角扫描，在两个脉冲中均观察到与OPTIMA光学偏振的${>}1\sigma$偏离，这表明这两个波段的偏振辐射可能具有不同的辐射机制或辐射源。 我们对星云内部区域的偏振图显示了类似先前IXPE分析所见的环形磁场。 沿着南部喷流，磁场方向相对于喷流轴从垂直变为平行，偏振度减少了${\sim}6\%$。 这些观测结果可以通过喷流中的kink不稳定现象或者喷流尖端与密集介质的碰撞来解释。 通过光谱偏振分析，我们在星云四个象限中发现了环形磁场预期的不对称偏振，并且偏振度与光子指数之间存在空间相关性。 显示英文摘要

摘要： We present Crab X-ray polarization measurements using IXPE data with a total exposure of 300ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped $+40^\circ$ polarization angle sweep in the main pulse and ${>}1\sigma$ departures from the OPTIMA optical polarization in both pulses, suggesting different radiation mechanisms or sites for the polarized emission at the two wavebands. Our polarization map of the inner nebula reveals a toroidal magnetic field, as seen in prior IXPE analyses. Along the southern jet, the magnetic field orientation relative to the jet axis changes from perpendicular to parallel and the polarization degree decreases by ${\sim}6\%$. These observations may be explained by kink instabilities along the jet or a collision with a dense, jet-deflecting medium at the tip. Using spectropolarimetric analysis, we find asymmetric polarization in the four quadrants of the inner nebula, as expected for a toroidal field geometry, and a spatial correlation between polarization degree and photon index.