Long-term study of the first Galactic ultraluminous X-ray source Swift J0243.6+6124 using NICER
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arXiv
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| Auteurs principaux: | , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866929225336881152 |
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| author | Chhotaray, Birendra Jaisawal, Gaurava K. Nandi, Prantik Naik, Sachindra kumari, Neeraj Ng, Mason Gendreau, Keith C. |
| author_facet | Chhotaray, Birendra Jaisawal, Gaurava K. Nandi, Prantik Naik, Sachindra kumari, Neeraj Ng, Mason Gendreau, Keith C. |
| contents | We present the results obtained from detailed X-ray timing and spectral studies of X-ray pulsar Swift J0243.6+6124 during its giant and normal X-ray outbursts between 2017 and 2023 observed by the Neutron star Interior Composition Explorer (NICER). We focused on the timing analysis of the normal outbursts. A distinct break is found in the power density spectra of the source. The corresponding break frequency and slope of power-laws around the break vary with luminosity, indicating the change in accretion dynamics with mass accretion rate. Interestingly, we detected quasi-periodic oscillations within a specific luminosity range, providing further insights into the underlying physical processes. We also studied the neutron star spin period evolution and a luminosity variation in pulse profile during the recent 2023 outburst. The spectral analysis was conducted comprehensively for the giant and all other normal outbursts. We identified a double transition at luminosities of $\approx$7.5$\times$10$^{37}$ and 2.1$\times$10$^{38}$ erg s$^{-1}$ in the evolution of continuum parameters like photon index and cutoff energy with luminosity. This indicates three distinct accretion modes experienced by the source mainly during the giant X-ray outburst. A soft blackbody component with a temperature of 0.08-0.7 keV is also detected in spectra. The observed temperature undergoes a discontinuous transition when the pulsar evolves from a sub- to super-Eddington state. Notably, in addition to an evolving 6-7 keV iron line complex, a 1 keV emission line was observed during the super-Eddington state of the source, implying the X-ray reflection from the accretion disc or outflow material. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_15058 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Long-term study of the first Galactic ultraluminous X-ray source Swift J0243.6+6124 using NICER Chhotaray, Birendra Jaisawal, Gaurava K. Nandi, Prantik Naik, Sachindra kumari, Neeraj Ng, Mason Gendreau, Keith C. High Energy Astrophysical Phenomena We present the results obtained from detailed X-ray timing and spectral studies of X-ray pulsar Swift J0243.6+6124 during its giant and normal X-ray outbursts between 2017 and 2023 observed by the Neutron star Interior Composition Explorer (NICER). We focused on the timing analysis of the normal outbursts. A distinct break is found in the power density spectra of the source. The corresponding break frequency and slope of power-laws around the break vary with luminosity, indicating the change in accretion dynamics with mass accretion rate. Interestingly, we detected quasi-periodic oscillations within a specific luminosity range, providing further insights into the underlying physical processes. We also studied the neutron star spin period evolution and a luminosity variation in pulse profile during the recent 2023 outburst. The spectral analysis was conducted comprehensively for the giant and all other normal outbursts. We identified a double transition at luminosities of $\approx$7.5$\times$10$^{37}$ and 2.1$\times$10$^{38}$ erg s$^{-1}$ in the evolution of continuum parameters like photon index and cutoff energy with luminosity. This indicates three distinct accretion modes experienced by the source mainly during the giant X-ray outburst. A soft blackbody component with a temperature of 0.08-0.7 keV is also detected in spectra. The observed temperature undergoes a discontinuous transition when the pulsar evolves from a sub- to super-Eddington state. Notably, in addition to an evolving 6-7 keV iron line complex, a 1 keV emission line was observed during the super-Eddington state of the source, implying the X-ray reflection from the accretion disc or outflow material. |
| title | Long-term study of the first Galactic ultraluminous X-ray source Swift J0243.6+6124 using NICER |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2401.15058 |