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arXiv · 2108.06365

SRG/ART-XC, Swift, NICER and NuSTAR study of different states of the transient X-ray pulsar MAXI J0903-531

Sergey S. Tsygankov·Sergey V. Molkov·Victor Doroshenko·Alexander A. Mushtukov·Ilya A. Mereminskiy·Andrei N. Semena·Philipp Thalhammer·Joern Wilms·Alexander A. Lutovinov
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Abstract

The results of the broadband spectral and timing study of the recently discovered transient X-ray pulsar MAXI J0903-531 in a wide range of luminosities differing by a factor of ~30 are reported. The observed X-ray spectrum in both states can be described as a classical pulsar-like spectrum consisting of the power-law with the high-energy cutoff. We argue that absence of the spectrum transformation to the two-hump structure expected at low fluxes points to a relatively weak magnetic field of the neutron star below (2-3)$\times10^{12}$ G. This estimate is consistent with other indirect constraints and non-detection of any absorption features which can be interpreted as a cyclotron absorption line. Timing analysis of the NuSTAR data revealed only slight variations of a single-peaked pulse profile of the source as a function of the energy band and mass accretion rate. In both intensity states the pulsed fraction increases from 40% to roughly 80% with the energy. Finally we were also able to obtain the orbital solution for the binary system using data from the Fermi/GBM, NICER and NuSTAR instruments.

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Sergey S. Tsygankov, Sergey V. Molkov, Victor Doroshenko, Alexander A. Mushtukov, Ilya A. Mereminskiy, Andrei N. Semena, Philipp Thalhammer, Joern Wilms, Alexander A. Lutovinov. 2021-08-13. SRG/ART-XC, Swift, NICER and NuSTAR study of different states of the transient X-ray pulsar MAXI J0903-531. https://doi.org/10.1051/0004-6361%2F202141821

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