NuSTAR discovery of a cyclotron absorption line in the transient X-ray pulsar 2S 1553-542
2016 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 457, no 1, 258-266 p.Article in journal (Refereed) PublishedText
We report the results of a spectral and timing analysis of the poorly studied transient X-ray pulsar 2S 1553-542 using data collected with the NuSTAR and Chandra observatories and the Fermi/GBM instrument during an outburst in 2015. The properties of the source at high energies (>30 keV) are studied for the first time and the sky position has been essentially improved. The source broad-band spectrum has a quite complicated shape and can be reasonably described by a composite model with two continuum components - a blackbody emission with the temperature about 1 keV at low energies and a power law with an exponential cut-off at high energies. Additionally, an absorption feature at similar to 23.5 keV is discovered both in phase-averaged and phase-resolved spectra and interpreted as the cyclotron resonance scattering feature corresponding to the magnetic field strength of the neutron star B similar to 3 x 10(12) G. Based on the Fermi/ GBM data, the orbital parameters of the system were substantially improved, which allowed us to determine the spin period of the neutron star P = 9.27880(3) s and a local spin-up. (P) over dot similar or equal to -7.5 x 10(-10) s s(-1) due to the mass accretion during the NuSTAR observations. Assuming accretion from the disc and using standard torque models, we estimated the distance to the system as d = 20 +/- 4 kpc.
Place, publisher, year, edition, pages
Oxford University Press, 2016. Vol. 457, no 1, 258-266 p.
accretion, accretion discs, magnetic fields, stars: individual: 2S 1553-542, X-rays: binaries
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:kth:diva-185358DOI: 10.1093/mnras/stv2849ISI: 000372599600017ScopusID: 2-s2.0-84961613293OAI: oai:DiVA.org:kth-185358DiVA: diva2:921914
QC 201604212016-04-212016-04-182016-04-21Bibliographically approved