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After about 18 years of steadily spinning down, the accretion-powered pulsar4U 1626-67, experienced a torque reversal at the beginning of 2008. For thepresent study we have used all available Fermi/GBM data since its launch in2008 June 11 and over 5 yr of hard X-ray Swift/BAT observations (starting from2004 October up to the present time). This second detected torque reversal iscentered near MJD 54500 (2008 Feb 4) and it lasts approximately 150 days. From2004 up to the end of 2007 4U 1626-67 the spin-down rate decreased at a meanrate of ~ -5.5E-13 Hz s-1 until the source reversed torque again. Since then ithas been following a steady spin-up at a mean rate of ~ 5E-13 Hz s-1. Inaddition, 4U 1626-67 increased its flux simultaneously (a ~2.5 factor). Wepresent detailed long-term timing analysis of this source and a long termspectral hardness ratio study in order to see whether there are spectralchanges around this new observed torque reversal.

New Torque Reversal and Spin-Up of 4u 1626- 67 Observed by Fermi/GBM and Swift/BAT