The NuSTAR hard X-ray telescope observed the transient Be/X-ray binary
GS 0834􀀀430 during its 2012 outburst. The source is detected between 3 – 79 keV with
high statistical significance, and we were able to perform very accurate spectral and timing
analysis. The phase-averaged spectrum is consistent with that observed in many other
magnetized accreting pulsars. We fail to detect cyclotron resonance scattering features
in either phase-averaged nor phase-resolved spectra that would allow us to constrain the
pulsar’s magnetic field. We detect a pulse period of ∼ 12.29 s in all energy bands. The pulse profile can be modeled with a double Gaussian and shows a strong and smooth hard lag of up to 0.3 cycles in phase, or about 4s between the pulse at ∼ 3 and >∼ 30 keV. This is the first report of such a strong lag in high-mass X-ray binary (HMXB) pulsars. Previously reported lags have been significantly smaller in phase and restricted to low-energies (E<10 keV). We investigate the possible mechanisms that might produce such lags. We find the most likely explanation for this eect to be a complex beam geometry.
|Conference||International Conference on Physics at the Magnetospheric Boundary|
|Period||25/06/2013 → 28/06/2013|
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