Volume 661, May 2022
The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG mission
|Number of page(s)||8|
|Section||Stellar structure and evolution|
|Published online||18 May 2022|
SRG/ART-XC, Swift, NICER, and NuSTAR study of different states of the transient X-ray pulsar MAXI J0903–531
Space Research Institute of the Russian Academy of Sciences,
Profsoyuznaya Str. 84/32,
2 Department of Physics and Astronomy, 20014 University of Turku, Finland
3 Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
4 Leiden Observatory, Leiden University, 2300 RA Leiden, The Netherlands
5 Dr. Remeis-Observatory & Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany
Accepted: 12 August 2021
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 that differ 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 a power law with a high-energy cutoff. We argue that the absence of the spectrum transformation to the two-hump structure that is expected at low fluxes indicates that the magnetic field of the neutron star is relatively weak below (2–3) × 1012 G. This estimate is consistent with other indirect constraints and non-detection of any absorption features that might be interpreted as a cyclotron absorption line. The 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.
Key words: accretion, accretion disks / magnetic fields / X-rays: binaries / stars: neutron / pulsars: individual: MAXI J0903-531 / radiative transfer
© ESO 2022
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