发表机构
University of Padova; INAF - Istituto di Astrofisica e Planetologia Spaziali; Mullard Space Science Laboratory, University College London; European Space Agency (ESA), European Space Astronomy Centre (ESAC); Institute of Space Sciences (ICE), CSIC; Institut d’Estudis Espacials de Catalunya (IEEC); University School for Advanced Studies IUSS Pavia（帕多瓦大学; 意大利国家天体物理研究所空间天体物理学和行星科学研究所; 伦敦大学学院穆拉德空间科学实验室; 欧洲航天局（ESA）欧洲空间天文中心（ESAC）; 西班牙高等科学研究理事会空间科学研究所（ICE）; 加泰罗尼亚空间研究研究所（IEEC）; 帕维亚高等研究大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过IXPE观测新磁星EP J223759.5+531421，探测到显著偏振X射线，揭示双热成分的不同偏振特性，并利用旋转矢量模型推断其辐射几何结构。
AI 中文摘要
我们报告了对新发现的银河系磁星EP J223759.5+531421的偏振X射线辐射的探测，该源由爱因斯坦探针宽视场X射线望远镜于2026年6月28日发现。成像X射线偏振探测器（IXPE）的后续观测于2026年7月6日开始，在2–7.5 keV能段探测到该源的（吸收）流量约为4.5×10^-11 erg cm^2 s^-1，确认了星体表面存在两个热辐射区域，温度分别约为0.5 keV和1 keV。在大于4σ置信水平下，探测到显著的相位和能量积分偏振度约为7%，偏振角约为天球北方向东-2°。两个热成分表现出截然不同的偏振特性，其中较热的成分偏振度更高。在相位折叠数据中差异更大，在4–7.5 keV能段内偏振度达到约63%，对应于脉冲轮廓的次级峰，而在较低能量下从未超过约30%。偏振角在一个旋转周期内从-90°连续振荡到+90°，并且很好地拟合了旋转矢量模型，视线倾角约为28°，磁偶极轴相对于恒星自转轴的倾角约为109°。数据表明其辐射几何结构为：冷热成分可能来自两个对跖极冠，可能处于磁凝聚态，而较热成分来自被大气覆盖的较小区域。
英文摘要
We report on the detection of polarized X-ray emission from the new Galactic magnetar EP J223759.5+531421, discovered by the Einstein Probe Wide-field X-ray Telescope on 2026 June 28. The Imaging X-ray Polarimetry Explorer (IXPE) follow-up observation started on 2026 July 6 and detected the source at a (absorbed) flux of $\approx 4.5\times 10^{-11} \, \mathrm{ erg\,cm^2\,s}^{-1}$ ($2$--$7.5\, \mathrm{keV}$ range), confirming the presence of two thermally emitting regions on the star surface, with temperatures $\approx 0.5$ and $\approx 1\, \mathrm{keV}$. A significant (at $> 4σ$ confidence level) phase- and energy-integrated polarization degree of $\approx 7\%$ was detected with the polarization angle $\approx -2^\circ$ East of the celestial North. The two thermal components exhibit quite different polarization properties, with the hotter one being more polarized. The difference is larger in the phase-folded data, with the polarization degree reaching $\sim 63\%$ in the range $4$--$7.5\,\mathrm{keV}$, in correspondence with the secondary peak of the pulse profile, and never exceeding $\sim 30\%$ at lower energies. The polarization angle continuously oscillates from $-90^\circ$ to $+90^\circ$ over one rotational cycle and is well fit by the rotating vector model, with an inclination of the line of sight and of the magnetic dipole axis relative to the star spin axis of $\approx 28^\circ$ and $\approx 109^\circ$, respectively. The data point to an emission geometry in which the cold thermal component likely originates from two antipodal caps, possibly in a magnetically condensed state, while the hotter one comes from a smaller region covered by an atmosphere.
Comments14 pages, 9 figures, submitted to ApJL
