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Title: A WHITE DWARF MERGER AS PROGENITOR OF THE ANOMALOUS X-RAY PULSAR 4U 0142+61?

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{sub Sun} white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses 0.6 M{sub Sun} and 1.0 M{sub Sun }. Finally, we infer a post-merging age {tau}{sub WD} Almost-Equal-To 64 kyr and a magnetic field B Almost-Equal-To 2 Multiplication-Sign 10{sup 8} 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 Almost-Equal-To 10{sup 15} Hz in the spectrum of 4U 0142+61.
Authors:
; ; ;  [1] ;  [2] ;  [3] ; ;  [4]
  1. Dipartimento di Fisica and ICRA, Sapienza Universita di Roma, P.le Aldo Moro 5, I-00185 Rome (Italy)
  2. School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)
  3. Institut de Ciencies de l'Espai (CSIC), Facultat de Ciencies, Campus UAB, Torre C5-parell, E-08193 Bellaterra (Spain)
  4. Institute for Space Studies of Catalonia, c/Gran Capita 2-4, Edif. Nexus 104, E-08034 Barcelona (Spain)
Publication Date:
OSTI Identifier:
22140323
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 772; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; APPROXIMATIONS; DETECTION; GAMMA RADIATION; MAGNETIC FIELDS; MASS; PULSARS; ROTATION; SPECTRA; WHITE DWARF STARS; X RADIATION