New measurements of the cyclotron line energy in Cen X-3

Abstract

We report results from the analysis of data from two observations of the accreting binary X-ray pulsar Cen X-3 carried out with the broadband X-ray observatories Suzaku and NuSTAR. The pulse profile is dominated by a broad single peak and show some energy dependence with two additional weak pulse peaks at energies below 15 and 25 keV respectively. The broadband X-ray spectrum for 0.8-60.0 keV for Suzaku and 3.0-60.0 keV for NuSTAR is fitted well with high energy cut-off power-law model along with soft-excess, multiple iron emission lines and a cyclotron absorption. The cyclotron line energy is found to be $30.29_{-0.61}^{+0.68}$ keV and $29.22_{-0.27}^{+0.28}$ keV respectively in the Suzaku and NuSTAR spectra. We make a comparison of these two measurements with four previous measurements of CRSF in Cen X-3 obtained with Ginga, BeppoSAX and RXTE. We find no evidence for a dependence of the CRSF on luminosity. Except for one CRSF measurement with BeppoSAX, the remaining measurements are consistent with a CRSF energy in the range of 29.5 - 30.0 keV over a luminosity range of 1.1-5.4 $\times 10^{37}$ ergs s${}^{-1}$ different from several other sources that show considerable CRSF variation in the same luminosity range.

8 pages, 5 figures, accepted for publication in MNRAS

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Cited by in corpus (6)

• Energy-resolved pulse profiles of accreting pulsars: Diagnostic tools for spectral features
• Discovery of Two Cyclotron Resonance Scattering Features in X-ray Pulsar Cen X-3 by Insight-HXMT
• Timing and spectral studies of Cen X-3 in multiple luminosity states using $\text{AstroSat}$
• Temporal and spectral variations of the X-ray pulsar Cen X-3 observed by NuSTAR
• Studying the variations of the cyclotron line in Cen X-3 using Insight-HXMT
• XMM-Newton view of pulsating iron fluorescent emission from Centaurus X3