Spectral analysis of an ultraluminous X-ray source Swift J0243.6+6124

Islamov, Gubad
In this thesis, the spectral analysis on the first galactic ultraluminous X-ray pulsar Swift J0243.6+6124 has been carried out. This peculiar object has been firstly observed by Swift observatory during its outburst in the late 2017 – early 2018 and it is a part of a Be/X-ray binary system. Observations obtained from NuSTAR observatory have been utilized in this study. The analysis showed that the source underwent drastic changes from the beginning of its outburst stage, during the peak of the outburst and after the outburst. The pulse-phase-resolved spectroscopy revealed that the source was accreting in two different regimes within the span of five observations – sub-critical and super-critical ones. The phase-dependent profiles of blackbody temperature and its normalization suggest that the source has a hot spot of a certain size which indicates the existence of a sub-critical accretion in pre- and post-outburst observations. It is also shown that the object also accretes in a clumpy way during the super-critical regime. The results of the analysis are consistent with the established theory and other publications, more clarity on the accretion details of the source during its outburst stage has been achieved as a result of this thesis study.


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Serim, Muhammed Miraç; Ozudogru, O. C.; Donmez, C. K.; Sahiner, S.; Serim, D.; Baykal, Altan; Inam, S. C. (2022-02-01)
We investigate timing and spectral characteristics of the transient X-ray pulsar 2S 1417-624 during its 2018 outburst with NICER follow up observations. We describe the spectra with high-energy cut-off and partial covering fraction absorption (PCFA) model and present flux-dependent spectral changes of the source during the 2018 outburst. Utilizing the correlation-mode switching of the spectral model parameters, we confirm the previously reported sub-critical to critical regime transitions and we argue that ...
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This thesis focuses on X-ray timing properties of four different X-ray binary systems, based on archival data of the X-ray missions RXTE, Swift, XMM-Newton, Chandra and Integral. One of the selected sources is a LMXB system GX 1+4 while remaining sources are BeXB systems: SWIFT J0513.4-6547, X Persei and SXP 1062. For GX 1+4, the timing analysis of RXTE-PCA observations between 2001 March 3 and 2003 January 31 are presented. The timing solutions of two different time intervals are constructed. Futhermore, w...
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Citation Formats
G. Islamov, “Spectral analysis of an ultraluminous X-ray source Swift J0243.6+6124,” M.S. - Master of Science, Middle East Technical University, 2021.