Revisiting the spectral and timing properties of 4U 1909+07 with NuSTAR and Astrosat

Show simple item record Jaisawal, Gaurava K. Naik, Sachindra Ho, Wynn C. G. Kumari, Neeraj Epili, Prahlad Vasilopoulos, Georgios 2020-09-03T06:25:09Z 2020-09-03T06:25:09Z 2020-08
dc.identifier.citation Jaisawal, Gaurava K.; Naik, Sachindra; Ho, Wynn C. G.; Kumari, Neeraj; Epili, Prahlad and Vasilopoulos, Georgios, "Revisiting the spectral and timing properties of 4U 1909+07 with NuSTAR and Astrosat", arXiv, Cornell University Library, DOI: arXiv:/2008.11093, Aug. 2020. en_US
dc.description.abstract We present the results obtained from the analysis of high-mass X-ray binary pulsar 4U 1909+07 using NuSTAR and Astrosat observations in July 2015 and 2017, respectively. X-ray pulsations at ≈604 s are clearly detected in our study. Based on the long-term spin-frequency evolution, the source is found to spun-up in the last 17 yr. We observed a strongly energy-dependent pulse profile that evolved from a complex broad structure in soft X-rays into a profile with a narrow emission peak followed by a plateau in energy ranges above 20 keV. This behaviour ensured a positive correlation between the energy and pulse fraction. The pulse profile morphology and its energy evolution are almost similar during both the observations, suggesting a persistent emission geometry of the pulsar over time. The broad-band energy spectrum of the pulsar is approximated by an absorbed high-energy exponential cut-off power-law model with iron emission lines. In contrast to the previous report, we found no statistical evidence for the presence of cyclotron absorption features in the X-ray spectra. We performed phase-resolved spectroscopy using data from the NuSTAR observation. Our results showed a clear signature of absorbing material at certain pulse phases of the pulsar. These findings are discussed in terms of stellar wind distribution and its effect on the beam geometry of this wind-fed accreting neutron star. We also reviewed the subsonic quasi-spherical accretion theory and its implication on the magnetic field of 4U 1909+07 depending on the global spin-up rate.
dc.description.statementofresponsibility by Gaurava K. Jaisawal, Sachindra Naik, Wynn C.G. Ho, Neeraj Kumari, Prahlad Epili and Georgios Vasilopoulos
dc.language.iso en_US en_US
dc.publisher Cornell University Library en_US
dc.subject stars en_US
dc.subject neutron � pulsars en_US
dc.subject individual en_US
dc.subject 4U 1909+07 � X-rays en_US
dc.subject stars en_US
dc.title Revisiting the spectral and timing properties of 4U 1909+07 with NuSTAR and Astrosat en_US
dc.type Pre-Print en_US

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