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New limits on the orbital parameters of 1E1048.1-5937 and 1E2259+586 from RossiXTE observations

S. Mereghetti·G. L. Israel·L. Stella
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Abstract

We report on two RossiXTE observations of the anomalous X-ray pulsars 1E 1048.1-5937 and 1E 2259+586. Both sources have continued their almost constant spin-down during 1995/96. We carried out a search for orbital Doppler shifts, in their observed spin frequencies, deriving stringent limits on the projected semi-axis. Unless these systems have unlikely small inclinations, main sequence companions can be excluded. If 1E 1048.1-5937 and 1E 2259+586 are indeed binary systems, their companion stars must be either white dwarfs, or helium-burning stars with M < 0.8 Msolar, possibly underfilling their Roche lobe.

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S. Mereghetti, G. L. Israel, L. Stella. 1997-10-29. New limits on the orbital parameters of 1E1048.1-5937 and 1E2259+586 from RossiXTE observations. https://doi.org/10.1046/j.1365-8711.1998.01396.x

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