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arXiv · 0912.3809

Discovery of a New Torque Reversal of the Accreting X-ray Pulsar 4U 1626-67 by Fermi/GBM

A. Camero-Arranz·M. H. Finger·N. R. Ikhsanov·C. A. Wilson-Hodge·E. Beklen
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Abstract

Recent X-ray observations by Fermi/GBM discovered a new torque reversal of 4U 1626-67 after 18 years of steady spinning down. Using Swift/BAT observations we were able to center this new torque reversal on Feb 4 2008, lasting approximately 150 days. From 2004 up to the end of 2007, the spin-down rate averaged at a mean rate of ~dnu/dt=-4.8e-13 Hz s-1 until the torque reversal reported here. Since then it has been following a steady spin-up at a mean rate of ~dnu/dt= 4e-13 Hz s-1. The properties of this torque reversal, as well as the lack of correlation between the X-ray flux and the torque applied to the neutron star before this transition, challenges our understanding of the physical mechanisms operating in this system.

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A. Camero-Arranz, M. H. Finger, N. R. Ikhsanov, C. A. Wilson-Hodge, E. Beklen. 2009-12-18. Discovery of a New Torque Reversal of the Accreting X-ray Pulsar 4U 1626-67 by Fermi/GBM. https://arxiv.org/abs/0912.3809

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