Abstract : A study of archival RXTE, Swift, and Suzaku pointed
observations of the transient high-mass X-ray binary GRO J1008−57 is presented. A new
orbital ephemeris based on pulse arrival-timing shows the times of maximum luminosities
during outbursts of GRO J1008−57 to be close to periastron at orbital phase − 0.03. This
makes the source one of a few for which outburst dates can be predicted with very high
precision. Spectra of the source in 2005, 2007, and 2011 can be well described by a simple
power law with high-energy cutoff and an additional black body at lower energies. The
photon index of the power law and the black-body flux only depend on the 15–50 keV source
flux. No apparent hysteresis effects are seen. These correlations allow us to predict the
evolution of the pulsar’s X-ray spectral shape over all outbursts as a function of just
one parameter, the source’s flux. If modified by an additional soft component, this
prediction even holds during GRO J1008−57’s 2012 type II outburst.
https://hal-cea.archives-ouvertes.fr/cea-01135403
Contributor : Edp Sciences
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Submitted on : Wednesday, March 25, 2015 - 12:24:22 PM
Last modification on : Tuesday, December 10, 2019 - 3:28:53 PM
Long-term archiving on: Thursday, July 2, 2015 - 6:55:26 AM
M. Kühnel, S. Müller, I. Kreykenbohm, F. Fürst, K. Pottschmidt, et al.. GRO J1008−57: an (almost) predictable transient X-ray binary. Astronomy and Astrophysics - A&A, EDP Sciences, 2013, 555, pp.A95. ⟨10.1051/0004-6361/201321203⟩. ⟨cea-01135403⟩
