Optical pulsations from the anomalous X-ray pulsar 1E 1048.1-5937

Abstract

We present high-speed optical photometry of the anomalous X-ray pulsar 1E 1048.1-5937 obtained with ULTRACAM on the 8.2-m Very Large Telescope in June 2007. We detect 1E 1048.1-5937 at a magnitude of i'=25.3+/-0.2, consistent with the values found by Wang et al. (2008) and hence confirming their conclusion that the source was approximately 1 mag brighter than in 2003-2006 due to an on-going X-ray flare that started in March 2007. The increased source brightness enabled us to detect optical pulsations with an identical period (6.458 s) to the X-ray pulsations. The rms pulsed fraction in our data is 21+/-7%, approximately the same as the 2-10 keV X-ray rms pulsed fraction. The optical and X-ray pulse profiles show similar morphologies and appear to be approximately in phase with each other, the latter lagging the former by only 0.06+/-0.02 cycles. The optical pulsations in 1E 1048.1-5937 are very similar in nature to those observed in 4U 0142+61. The implications of our observations for models of anomalous X-ray pulsars are discussed.

arXiv comment5 pages, 3 figures, accepted for publication in MNRAS Letters

References in corpus (17)

• The u'g'r'i'z' Standard Star Network
• Corona of Magnetars
• ULTRACAM: an ultra-fast, triple-beam CCD camera for high-speed astrophysics
• An Accretion Model for Anomalous X-Ray Pulsars
• On Young Neutron Stars as Propellers and Accretors with Conventional Magnetic Fields
• An Optical Counterpart to the Anomalous X-ray Pulsar 4U 0142+61
• Emission Spectra of Fallback Disks Around Young Neutron Stars
• Anomalous X-ray Pulsar 1E 1048.1-5937: Pulsed Flux Flares and Large Torque Variations
• Anomalous X-ray pulsars: Persistent States with Fallback Disks
• X-ray and Near-IR Variability of the Anomalous X-ray Pulsar 1E 1048.1-5937: From Quiescence Back to Activity
• Long-Term RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937
• Extinction Columns and Intrinsic X-ray Spectra of the Anomalous X-ray Pulsars
• Chandra Observations of the Anomalous X-ray Pulsar 4U 0142+61
• High-speed, multi-colour optical photometry of the anomalous X-ray pulsar 4U 0142+61 with ULTRACAM
• The Broad-Band Spectrum and Infrared Variability of the Magnetar AXP 1E1048.1-5937
• The Anomalous X-Ray Pulsar 4U 0142+61: A Neutron Star with a Gaseous Fallback Disk
• Optical/Infrared Observations of the Anomalous X-ray Pulsar 1E 1048.1-5937 During Its 2007 X-Ray Flare

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