English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Spin period variations and hard X-ray spectral properties of Be/X-ray pulsarGRO J1008-57 are studied with INTEGRAL observations. The pulsation periods at93.66 s in 2004 and at 93.73 s in 2009 are determined. Pulse profiles of GROJ1008-57 during outbursts are energy dependent: double-peak profile in softbands of 3-7 keV and single-peak profile in hard X-rays above 7 keV. GROJ1008-57 has undergone a spin-down trend from 1993-2009 with a rate of4.1x10^-5 s day^-1, and might transfer into a spin-up trend after 2009. Thespectra from 3-100 keV of GRO J1008-57 during outbursts are fitted with photonindex of 1.4 and cutoff energies of 23-29 keV. We find a relatively softspectrum in early phase of the 2009 outburst with cutoff energy 13 keV. Above ahard X-ray flux of 10^-9 erg cm^-2 s^-1, the spectra of GRO J1008-57 duringoutbursts need an enhanced hydrogen absorption of column density 6x10^22 cm^-2.The observed dip-like pulse profile of GRO J1008-57 in soft X-ray bands shouldbe caused by this intrinsic absorption. Around the outburst peaks, a possiblecyclotron resonance scattering feature at 74 keV is detected in the spectra ofGRO J1008-57, making the source as the neutron star of highest magnetic field(6.6x10^12 G) in known accreting X-ray pulsars. Two modulations periods at124.38 and 248.78 days are found using RXTE/ASM light curves of GRO J1008-57.Two flare peaks appearing in the folded light curve have different spectralproperties. The normal outburst lasting 0.1 orbital phase has a hard spectrumand cannot be detected below 3 keV. The second flare lasting ten days shows avery soft spectrum without significant detections above 5 keV. Lack of softX-ray emissions in outbursts should be caused by the enhanced hydrogenabsorption near the periastron passage. Soft spectral origins in the secondflares still need further detailed studies with soft X-ray spectroscopies.

Temporal Variations And Spectral Properties of Be/X-ray Pulsar GRO J1008-57 Studied by INTEGRAL