Open AccessThin accretion discs around millisecond X‐ray pulsars
Author(s) -
Tessema Solomon Belay,
Torkelsson Ulf
Publication year - 2011
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2010.18002.x
Subject(s) - physics , millisecond pulsar , astrophysics , pulsar , neutron star , millisecond , accretion (finance) , dynamo , dipole , x ray pulsar , magnetic dipole , astronomy , magnetic field , quantum mechanics
Millisecond X‐ray pulsars have weak magnetic dipole moments of ∼10 16 T m 3 compared to ordinary X‐ray pulsars with dipole moments of 10 20 T m 3 . For this reason a surrounding accretion disc can extend closer to the millisecond X‐ray pulsars, and thus reach a higher temperature, at which the opacity is dominated by electron scattering and radiation pressure is strong. We compute the self‐similar structure of such a geometrically thin axisymmetric accretion disc with an internal dynamo. Such models produce significantly stronger torques on the neutron star than models without dynamos, and can explain the strong spin variations in some millisecond X‐ray pulsars.