MAXI J0911-655 (Swift J0911.9-6452)是2016年在球狀星團NGC 2808中被發現的吸積毫秒脈衝星，脈衝周期約為2.94毫秒。在首度被發現後，許多太空X光望遠鏡皆有對此光源觀測，其中包含Swift、INTEGER、Chandra、XMM-Newton及 NuSTAR。其中因為XMM-Newton及NuSTAR有很好的時間解析度及較大的有效集光面積，所以在本論文中將利用這二個望遠鏡的觀測資料進行分析。 本論文的研究目標是要探討不同能量之脈衝抵達時間的變化。為了比較脈衝抵達時間，我們需要透過精確的軌道與自轉參數，獲得不同能量的精確脈衝波形。我們藉由脈衝抵達時間延遲的方法，將先前發表的已知參數確認並修正至更準確。接著依能量將光子區分為數個能帶後，利用本研究獲得的參數疊合不同能帶獲得疊合光變曲線，並透過線性擬合取得脈衝波形。每個能帶與最低能帶的脈衝波形透過互相關算得之間的相位差，藉此比較不同能量的脈衝抵達時間變化。 我們透過XMM-Newton及NuSTAR的觀測資料，發現MAXI J0911-655在能量0.3到78 keV間，有高達0.24個相位(~700 μs)的低能延遲現象。根據二分量模型，在都卜勒增亮的影響下，康普頓分量與黑體輻射分量之間的角度分布範圍差別，將造成了觀測到的低能延遲現象。在本研究中，將根據低能延遲的變化討論不同的爆發時間下，熱點與吸積衝擊層的改變狀況。 ;MAXI J0911-655 (Swift J0911.9-6452), an accreting millisecond X-ray pulsar located in globular cluster NGC 2808, was discovered in 2016 with a pulsation period of 2.94 ms. The follow-up observations were made by Swift, INTEGER, Chandra, XMM-Newton and NuSTAR. Our analysis based on the observation data of XMM-Newton and NuSTAR owing to their better time resolution and larger effective area. In this study, we attempted to detect the energy dependent pulse arrival time lags, which have been seen in other AMXPs. To obtain the correct pulse profile, precise orbital and spin parameters are essential. We first applied the orbital and spin parameters that yielded by previous study and then refined them using pulse arrival time delay technique. These photons were further divided into several energy bands and then folded with the best orbital and spin parameters to make the pulse profiles of these bands. The pulse arrival time lags relative to the softest energy band were evaluated through cross correlation of the best fitted pulse profiles. We found the soft lags could be up to 0.24 cycle (~700 μs) in the energy range of 0.3 to 78 keV by XMM-Newton and NuSTAR observations. According to the two-component model, by the influence of Doppler boosting, the different angular distribution between Comptonized (fan-like) and blackbody (pen-like) components is an important reason to cause the soft lag. In this study, we tried to discussion the hotspot and accretion shock change for different outburst time by soft lag magnitudes.
