A White Dwarf Merger as Progenitor of the Anomalous X-Ray Pulsar 4U 0142+61?
Abstract
It has been recently proposed that massive, fast-rotating, highly magnetized white dwarfs could describe the observational properties of some of soft gamma-ray repeaters and anomalous X-ray pulsars (AXPs). Moreover, it has also been shown that high-field magnetic white dwarfs can be the outcome of white dwarf binary mergers. The products of these mergers consist of a hot central white dwarf surrounded by a rapidly rotating disk. Here we show that the merger of a double degenerate system can explain the characteristics of the peculiar AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We also show that the observed properties of 4U 0142+6 are consistent with an approximately 1.2 M ⊙ white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses 0.6 M ⊙ and 1.0 M ⊙. Finally, we infer a post-merging age τWD ≈ 64 kyr and a magnetic field B ≈ 2 × 108 G. Evidence for such a magnetic field may come from the possible detection of the electron cyclotron absorption feature observed between the B and V bands at ≈1015 Hz in the spectrum of 4U 0142+61.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2013
- DOI:
- 10.1088/2041-8205/772/2/L24
- arXiv:
- arXiv:1306.5936
- Bibcode:
- 2013ApJ...772L..24R
- Keywords:
-
- pulsars: general;
- pulsars: individual: 4U 0142+61;
- stars: magnetic field;
- stars: rotation;
- white dwarfs;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena;
- General Relativity and Quantum Cosmology
- E-Print:
- to appear in ApJ Letters