Quantum effects in cyclotron plasma absorption

G. G. Pavlov, Yu A. Shibanov, D. G. Yakovlev

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Abstract

It is shown that X-ray radiation of neutron stars with magnetic fields B=1011-1013 G near cyclotron resonances ω=sωB(s=1,2,...) is deeply affected by such quantum effects as electron-positron vacuum polarization (significant at V=3×1028ne-1(B/BC4)≳1, where BC=4.4×1013G), the quantizing character of the magnetic field (significant at V=3 x 1028ne-1(B/Bc)4≳1 where Bc=4.4 x 1013G), the non-harmonic character of the Landau levels, and the quantum recoil of electrons. The latter two factors shift the resonances by the frequency -s2ωB(B/2 Bc)sin2θ{symbol}, θ{symbol} being the angle between the direction of radiation propagation and the magnetic field. If V≪V0 (for θ{symbol}∼1, V0∼β-1=(mc2/2 T)1/2), the normal mode (NM) polarizations, as well as the absorption coefficient k1 of the extraordinary NM in the Doppler core of the first resonance (|ω-ω| ≲ωBβ cos θ{symbol}), is only slightly affected by varying b and/or V, whereas for the ordinary NM (at θ{symbol}∼1)k2∼k1β2[b + (3 + tan2θ{symbol}-2 V)2]≪k1. For sufficiently large b and/or V the quantum effects amplify resonant absorption of the ordinary NM at ω∼ωB, with spin-flip transitions playing a major role at b≳1+V2. If V∼V0, the coefficients k1 and k2 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≫V0, k2=k1(cos2 θ{symbol}+B/2 BC) and the polarizations are almost linear. Near high resonances (s≥2), as a rule, k1,2α(1 + b)s-1β2 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}ωB. 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 languageEnglish (US)
Pages (from-to)33-62
Number of pages30
JournalAstrophysics and Space Science
Volume73
Issue number1
DOIs
StatePublished - Nov 1 1980

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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