## Abstract

It is shown that X-ray radiation of neutron stars with magnetic fields B=10^{11}-10^{13} G near cyclotron resonances ω=sω_{B}(s=1,2,...) is deeply affected by such quantum effects as electron-positron vacuum polarization (significant at V=3×10^{28}n_{e}^{-1}(B/B_{C}^{4})≳1, where B_{C}=4.4×10^{13}G), the quantizing character of the magnetic field (significant at V=3 x 10^{28}n_{e}^{-1}(B/B_{c})^{4}≳1 where B_{c}=4.4 x 10^{13}G), the non-harmonic character of the Landau levels, and the quantum recoil of electrons. The latter two factors shift the resonances by the frequency -s^{2}ω_{B}(B/2 B_{c})sin^{2}θ{symbol}, θ{symbol} being the angle between the direction of radiation propagation and the magnetic field. If V≪V_{0} (for θ{symbol}∼1, V_{0}∼β^{-1}=(mc^{2}/2 T)^{1/2}), the normal mode (NM) polarizations, as well as the absorption coefficient k_{1} of the extraordinary NM in the Doppler core of the first resonance (|ω-ω| ≲ω_{B}β cos θ{symbol}), is only slightly affected by varying b and/or V, whereas for the ordinary NM (at θ{symbol}∼1)k_{2}∼k_{1}β^{2}[b + (3 + tan^{2}θ{symbol}-2 V)^{2}]≪k_{1}. For sufficiently large b and/or V the quantum effects amplify resonant absorption of the ordinary NM at ω∼ω_{B}, with spin-flip transitions playing a major role at b≳1+V^{2}. If V∼V_{0}, the coefficients k_{1} and k_{2} in the Doppler core of the resonance are of the same order and acquire some peculiar features (shifts, intersections, etc.), with the NM polarizations depending sharply on ω and being strongly non-orthogonal. At V≫V_{0}, k_{2}=k_{1}(cos^{2} θ{symbol}+B/2 B_{C}) and the polarizations are almost linear. Near high resonances (s≥2), as a rule, k_{1,2}α(1 + b)^{s-1}β^{2 s-3} i.e., absorption increases with b due to replacement of the thermal energy of the transverse motion of electron, T, by the magnetic energy h{combining short stroke overlay}ω_{B}. The above effects should be taken into account for an interpretation of observational data on X-ray pulsars (e.g., Her X-1) and other X-ray sources associated with neutron stars.

Original language | English (US) |
---|---|

Pages (from-to) | 33-62 |

Number of pages | 30 |

Journal | Astrophysics and Space Science |

Volume | 73 |

Issue number | 1 |

DOIs | |

State | Published - Nov 1 1980 |

## All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science