Devaraj, A and Sharma, R and Nagesh, S and Paul, B (2024) Insights into the phase-dependent cyclotron line feature in XTE J1946 + 274:ãn AstroSatãnd Insight -HXMT view. In: Monthly Notices of the Royal Astronomical Society, 527 (4). pp. 11015-11025.
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Abstract
XTE J1946 + 274 isã Be/X-ray binary withã 15.8 s spin periodãnd 172 d orbital period. Using RXTE/PCA data of the 1998 outburst,ã cyclotron lineãround 37 k eV wãs reported. The presence of this line, its dependence on the pulse phase,ãnd its variation with luminosity have been of some debate since. In this work, we present the re-analysis of two AstroSat observations: one made during the rising phase of the 2018 outburstãnd the other during the declining phase of the 2021 outburst. Weãlso presentã newãnalysis of the Insight -HXMT observations of the sourceãt the peak of the 2018 outburst. We find the source to be spinning up o v er the course of the outburstãnd spinning down between the two outbursts. We report the presence ofã higher cyclotron line energy using the 2018 AstroSat observation ( �45 keV)ãnd 2018 Insight -HXMT observation ( �50 keV)ãndã lineãt �40 keV during the declining phase of the 2021 outburst using data from AstroSat . Weãlso investigate the pulse phase dependence of the cyclotron line parametersãnd find that the line is significantly detected inãll the phases of both AstroSat observãtions,ãlong with sho wing vãriation with the pulse phase. This dif fers from the pre vious results reported using BeppoSAXãnd NuSTAR . We explain this behaviour of the cyclotron line to be due to photon spawningãnd differentãccretion column radiiãt the two poles of this neutron star. © 2023 The Author(s).
| Item Type: | Journal Article |
|---|---|
| Publication: | Monthly Notices of the Royal Astronomical Society |
| Publisher: | Oxford University Press |
| Additional Information: | The copyright for this article belongs to author. |
| Keywords: | Pulsars, Be-X-rays:binaries; Cyclotron lines; Line features; Phase dependent; Pulsars: general; Pulse phase; Stars: neutrons; X-ray: individual: XTE j1946 + 274; X-rays: Binaries; X-rays: individual, Cyclotrons |
| Department/Centre: | Division of Physical & Mathematical Sciences > Astronomy and Astrophysics Programme Division of Physical & Mathematical Sciences > Joint Astronomy Programme |
| Date Deposited: | 04 Mar 2024 06:41 |
| Last Modified: | 04 Mar 2024 06:41 |
| URI: | https://eprints.iisc.ac.in/id/eprint/84158 |
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