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Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses
Published on: July 2, 2012
Optical pulsations from the anomalous X-ray pulsar 4U0142+61
1Division of Physics, Mathematics, and Astronomy, California Institute of Technology, MS 405-47, Pasadena, California 91125, USA. bdk@srl.caltech.edu
Nature
|May 31, 2002
Summary
Anomalous X-ray pulsars (AXPs) are highly magnetized neutron stars called magnetars. Optical pulsations detected from AXP 4U0142+61 confirm its magnetar nature, linking AXPs and soft gamma-ray repeaters.
Area of Science:
- Astronomy and Astrophysics
- High-energy astrophysics
- Neutron star physics
Background:
- Anomalous X-ray pulsars (AXPs) exhibit X-ray luminosities far exceeding their rotational energy loss, suggesting an alternative energy source.
- Magnetars, neutron stars with surface magnetic fields >10^14 G, are a leading hypothesis for AXPs, aligning them with soft gamma-ray repeaters (SGRs).
- Previous observations of AXP 4U0142+61's optical counterpart were consistent with magnetars, but also with other objects like magnetized white dwarfs or accreting neutron stars.
Purpose of the Study:
- To investigate the nature of Anomalous X-ray Pulsar 4U0142+61 by searching for optical pulsations.
- To differentiate between magnetar models and alternative explanations for AXP 4U0142+61's emission.
- To establish a direct observational link between AXPs and soft gamma-ray repeaters.
Main Methods:
- Detection of optical pulsations from the X-ray binary 4U0142+61.
- Measurement of the pulsed fraction of optical light.
- Comparison of optical pulsed fraction with X-ray pulsed fraction.
Main Results:
- Optical pulsations were detected from AXP 4U0142+61.
- The pulsed fraction of optical light was measured at 27%.
- The optical pulsed fraction is 5-10 times greater than the soft X-ray pulsed fraction.
Conclusions:
- The detection of significant optical pulsations confirms that 4U0142+61 is a magnetar.
- This finding establishes a direct observational relationship between Anomalous X-ray Pulsars and soft gamma-ray repeaters.
- The precise evolutionary pathways connecting AXPs, SGRs, and ordinary radio pulsars remain an open question.
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