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Long-Term Monitoring of Anomalous X-ray Pulsars

Fotis P. Gavriil·Victoria M. Kaspi·Deepto Chakrabarty
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Abstract

We report on long-term monitoring of anomalous X-ray pulsars (AXPs) using the Rossi X-ray Timing Explorer. Using phase-coherent timing, we find a wide variety of behaviors among the sources, ranging from high stability (in 1E 2259.1+586 and 4U 0142+61), to instabilities so severe that phase-coherent timing is not possible (in 1E 1048.1-5937). We note a correlation in which timing stability in AXPs decreases with increasing spin-down rate. The timing stability of soft gamma repeaters in quiescence is consistent with this trend, which is similar to one seen in radio pulsars. We consider high signal-to-noise ratio average pulse profiles as a function of energy for each AXP, and find a variety of behaviors. We find no large variability in pulse morphology nor in pulsed flux as a function of time.

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Fotis P. Gavriil, Victoria M. Kaspi, Deepto Chakrabarty. 2001-11-29. Long-Term Monitoring of Anomalous X-ray Pulsars. https://arxiv.org/abs/astro-ph/0111562

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