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arXiv 2501.05511astro-ph.HE
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GX 13+1中的X射线凹陷与偏振角摆动

X-ray Dips and Polarization Angle Swings in GX 13+1

Alessandro Di Marco, Fabio La Monaca, Anna Bobrikova, Luigi Stella, Alessandro Papitto, Juri Poutanen, Maria Cristina Baglio, Matteo Bachetti, Vladislav Loktev,… 展开作者

Alessandro Di Marco, Fabio La Monaca, Anna Bobrikova, Luigi Stella, Alessandro Papitto, Juri Poutanen, Maria Cristina Baglio, Matteo Bachetti, Vladislav Loktev, Maura Pilia, Daniele Rogantini

AI总结:

通过IXPE、NICER和Swift-XRT协同观测低质量X射线双星GX 13+1,发现其X射线凹陷期间偏振度更高且偏振角摆动约70°,揭示偏振特性与强度及光谱硬度变化相关,为吸积盘等模型提供依据。

摘要:

我们展示了2024年4月使用成像X射线偏振探测器(IXPE)对低质量X射线双星GX 13+1的观测结果,以及NICER和Swift-XRT的协同观测数据。观测到两个光变曲线凹陷;在此期间,较硬的康普顿化光谱成分占主导,偏振度高于较软的非凹陷区间。通过对三次IXPE观测(包括首次观测中的凹陷)的联合分析,我们证明偏振特性随凹陷相关的强度和光谱硬度变化而变化。偏振度最高达到约4%。偏振角在凹陷和非凹陷状态间摆动约70°,与首次IXPE观测中看到的连续旋转相当。我们在吸积盘和中子星表面边界/扩展层的偏振发射模型背景下讨论这些结果,还关注了扩展吸积盘冕或盘风在产生高偏振度和可能的偏振角摆动中的作用。

英文摘要:

We present the result from the April 2024 observation of the low-mass X-ray binary GX 13+1 with the Imaging X-ray Polarimetry Explorer (IXPE), together with NICER and Swift-XRT coordinated observations. Two light curve dips were observed; during them, the harder Comptonized spectral component was dominant and the polarization degree higher than in the softer, off-dip intervals. Through a joint analysis of the three IXPE observations, which also included the dip from the first observation, we demonstrate that the polarization properties varied in response to the intensity and spectral hardness changes associated with the dips. The polarization degree attained values up to ~4%. The polarization angle showed a swing of ~70° across the dip and off-dip states, comparable to the continuous rotation seen during the first IXPE observation. We discuss these results in the context of models for polarized emission from the accretion disk and the boundary/spreading layer on the neutron star surface. We also draw attention to the role that an extended accretion disk corona or disk wind can play in generating high polarization degrees and, possibly, swings of the polarization angle.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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