Firm Detection of a Cyclotron Resonance Feature with Suzaku in the X-ray Spectrum of GRO J1008-57 during a Giant Outburst in 2012

Abstract

We report on the firm detection of a cyclotron resonance scattering feature (CRSF) in the X-ray spectrum of the Be X-ray binary pulsar, GRO J1008-57, achieved by the Suzaku Hard X-ray Detector during a giant outburst which was detected by the MAXI Gas Slit Camera in 2012 November. The Suzaku observation was carried out on 2012 November 20, outburst maximum when the X-ray flux reached $\sim 0.45$ Crab in 4-10 keV, which corresponds to a luminosity of $1.1\times 10^{38}$ erg s${}^{-1}$ in 0.5--100 keV at 5.8 kpc. The obtained broadband X-ray spectrum from 0.5 keV to 118 keV revealed a significant absorption feature, considered as the fundamental CRSF, at $\sim 76$ keV. This unambiguously reconfirm the previously suggested $\sim$ 80 keV spectral feature in GRO J1008$-$57. The implied surface magnetic field, $6.6\times 10^{12}$ G, is the highest among binary X-ray pulsars from which CRSFs have ever been detected.

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• Correlation between the luminosity and spin-period changes during outbursts of 12 Be binary pulsars observed by the MAXI/GSC and the Fermi/GBM
• Relation of cyclotron resonant energy and luminosity in a strongly magnetized neutron star GRO J1008-57 observed by Insight-HXMT
• Insight-HXMT firm detection of the highest energy fundamental cyclotron resonance scattering feature in the spectrum of GRO J1008-57
• An XMM-Newton and NuSTAR study of IGR J18214-1318: a non-pulsating high-mass X-ray binary with a neutron star
• An application of the Ghosh & Lamb model to the accretion powered X-ray pulsar X Persei
• Dynamical Effects of Magnetic Opacity in Neutron Star Accretion Columns
• Radio monitoring of transient Be/X-ray binaries and the inflow-outflow coupling of strongly-magnetized accreting neutron stars
• Evidence for different accretion regimes in GRO J1008-57
• Discovery of X-ray pulsations in the Be/X-ray binary IGR J06074+2205
• Hard X-ray/Soft gamma-ray experiments and missions: overview and prospects
• X-ray emission evolution of the Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124 during the 2017-2018 outburst observed by the MAXI GSC
• Evolution implications of neutron star magnetic fields: inferred from pulsars and cyclotron lines of HMXBs