Long-Term RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937

Abstract

We report on long-term monitoring of the anomalous X-ray pulsar (AXP) 1E 1048.1-5937 using the Rossi X-ray Timing Explorer (RXTE). The timing behavior of this pulsar is different from that of other AXPs being monitored with RXTE. In particular, we show that the pulsar shows significant deviations from simple spin-down such that phase-coherent timing has not been possible over time spans longer than a few months. We find that the deviations from simple spin down are not consistent with single "glitch" type events, nor are they consistent with radiative precession. We show that in spite of the rotational irregularities, the pulsar exhibits neither pulse profile changes nor large pulsed flux variations. We discuss the implications of our results for AXP models. In the context of the magnetar model, we suggest that 1E 1048.1-5937 may be a transition object between the soft gamma-ray repeater and AXP populations, and the AXP most likely to one day undergo an outburst.

27 pages, 4 figures, to appear in August issue of ApJ. Revised text and Figure 3

References in corpus (15)

• An Accretion Model for Anomalous X-Ray Pulsars
• An Optical Counterpart to the Anomalous X-ray Pulsar 4U 0142+61
• Physical Mechanisms for the Variable Spin-down of SGR 1900+14
• Evidence for a Sudden Magnetic Field Reconfiguration in SGR 1900+14
• Precision Timing of Two Anomalous X-Ray Pulsars
• Nature vs. Nurture: The Origin of Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• Bumpy Spin-Down of Anomalous X-Ray Pulsars: The Link with Magnetars
• A Glitch in an Anomalous X-ray Pulsar
• X-ray observations of the high magnetic field radio pulsar PSR J1814-1744
• Timing Noise in SGR 1806-20
• Is SGR 1900+14 a Magnetar?
• Study of the Long Term Stability of two Anomalous X-ray Pulsars 4U 0142+61 and 1E 1048.1-5937 with ASCA
• The Spin Period, Luminosity and Age Distributions of Anomalous X-Ray Pulsars
• An RXTE Observation of the Vela Pulsar: Filling in the X-ray Gap
• Differences between the Two Anomalous X-Ray Pulsars: Variations in the Spin Down Rate of 1E 1048.1-5937 and An Extended Interval of Quiet Spin Down in 1E 2259+586

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• A Major SGR-like Outburst and Rotation Glitch in the No-Longer-So-Anomalous X-ray Pulsar 1E 2259+586
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• Discovery of luminous pulsed hard X-ray emission from anomalous X-ray pulsars 1RXS J1708-4009, 4U 0142+61 and 1E 2259+586 by INTEGRAL and RXTE
• Grand Unification in Neutron Stars
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• Recent Progress on Anomalous X-ray Pulsars
• Large Torque Variations in Two Soft Gamma Repeaters
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• RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937: Long-Term Variability and the 2007 March Event
• 1E 1207.4-5209: The puzzling pulsar at the center of the PKS 1209-51/52 supernova remnant
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• Electrodynamics of Magnetars III: Pair Creation Processes in an Ultrastrong Magnetic Field and Particle Heating in a Dynamic Magnetosphere
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• NuSTAR Observations of Magnetar 1E 1048.1-5937
• Implications of magnetar non-precession
• Mapping the Surface of the Magnetar 1E 1048.1-5937 in Outburst and Quiescence Through Phase Resolved X-ray Spectroscopy
• The Broad-band Noise Characteristics of Selected Anomalous X-Ray Pulsars and Soft Gamma-ray Repeaters