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arXiv · 0812.4189

Recent Torque Reversal of 4U 1907+09

S. C. Inam·S. Sahiner·A. Baykal
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Abstract

We present timing and spectral analysis of RXTE-PCA observations of the accretion powered pulsar 4U 1907+09 between June 2007 and August 2008. 4U 1907+09 had been in a spin-down episode with a spin-down rate of $-3.54\times10^{-14}$ Hz s$^{-1}$ before 1999. From RXTE observations after March 2001, the source showed a $\sim 60$% decrease in spin-down magnitude and INTEGRAL observations after March 2003 showed that source started to spin-up. We found that the source recently entered a new spin-down episode with a spin-down rate of $-3.59 \times 10^{-14}$ Hz s$^{-1}$. This spin-down rate is pretty close to the previous long term spin-down rate of the source measured before 1999. From the spectral analysis, we showed that Hydrogen column density varies with the orbital phase.

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S. C. Inam, S. Sahiner, A. Baykal. 2009-05-15. Recent Torque Reversal of 4U 1907+09. https://doi.org/10.1111/j.1365-2966.2009.14596.x

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