A1 Refereed original research article in a scientific journal
Measuring the Magnetic Field Strength of a Transient X-ray Pulsar 4U 1901+03 by Its Variability on Different Time Scales
Authors: Mereminskiy, I. A.; Semena, A. N.; Lutovinov, A. A.; Tsygankov, S. S.; Molkov, S. V.; Karasev, D. I.
Publisher: Pleiades Publishing Ltd
Publishing place: NEW YORK
Publication year: 2025
Journal: Astronomy Letters / Pis'ma v Astronomicheskii Zhurnal
Journal name in source: Astronomy Letters
Journal acronym: ASTRON LETT+
Volume: 50
Issue: 10
First page : 600
Last page: 607
Number of pages: 8
ISSN: 1063-7737
eISSN: 1562-6873
DOI: https://doi.org/10.1134/S1063773724700506
Web address : https://doi.org/10.1134/s1063773724700506
By combining data from several X-ray telescopes (Swift/XRT, NICER, Chandra) we reconstructed a profile of the 2019 outburst of accreting X-ray pulsar 4U 1901+03 from its peak down to the return to the "low" state. Softening of the X-ray spectrum and disappearance of the pulsations at a later stages of the outburst tentatively indicates that the source transitioned to the "propeller" state at luminosity about 10(36) erg s(-1), which corresponds to a magnetic field strength of B less than or similar to 10(12) G at the neutron star surface. We also investigated the fast X-ray variability that was observed during the peak of 2003 outburst. The shape of the power spectrum could be described with a broken power law, with a break frequency of 7.5 Hz. Assuming that this frequency corresponds to a viscous frequency at a magnetospheric boundary we estimated magnetic field strength as B approximate to 7 x 10(11) G, which is similar to the estimate obtained from observed transition to the "propeller" regime.
Funding information in the publication:
This study was supported by the Ministry of Science and Higher Education of the Russian Federation (grant no. 075-15-2024-647).
