Possible Periodic Dips in the Pulsating Ultraluminous X-Ray Source M51 ULX-7
Possible Periodic Dips in the Pulsating Ultraluminous X-Ray Source M51 ULX-7
复制标题
DOI：
10.3847/1538-4357/abd7a5
复制
发表时间：
2021-02
期刊：
影响因子：
--
通讯作者：
Chin-Ping Hu;Y. Ueda;T. Enoto
中科院分区：
文献类型：
--
作者：
Chin-Ping Hu;Y. Ueda;T. Enoto
我们报告发现可能的周期性的X射线下降的脉动超亮X射线源，M51 ULX-7，与档案钱德拉观测。在超轨道下降状态下进行了200天的监测，我们通过贝叶斯块技术发现了三个间隔为202天和208天的下降。相位色散最小化和一项测试表明，倾斜可能是周期性的，周期为102天，与M51 ULX-7的轨道周期一致。我们解释的倾角作为一个模糊的辐射从脉冲星的流盘相互作用区域或大气的伴星星星的垂直结构。这两种解释都认为视角为60°。鉴于M51 ULX-7的磁场中等偏高，B = 1013 G，低几何波束足以解释观测到的通量和倾角的存在。恒星风的昏暗仍然是另一种可能的来源，需要进一步监测倾角。
We report the discovery of possible periodic X-ray dips in a pulsating ultraluminous X-ray source, M51 ULX-7, with archival Chandra observations. With ∼20 days of monitoring in the superorbital descending state, we discovered three dips with separations of ∼2 and ∼8 days via the Bayesian block technique. A phase-dispersion minimization and a test suggest that the dip is likely recurrent with a period of ∼2 days, consistent with the orbital period of M51 ULX-7. We interpret the dip as an obscuring of the emission from the pulsar by the vertical structure on the stream–disk interaction region or the atmosphere of the companion star. Both interpretations suggest the viewing angle to be ∼60°. Given that the magnetic field of M51 ULX-7 is moderately high, B ∼ 1013 G, a low geometric beaming with is sufficient to explain the observed flux and the presence of dips. Obscuration of the stellar wind remains an alternative possible origin and further monitoring of the dips will be required.