Resonant cyclotron scattering (RCS) in pulsar magnetospheres is considered.
The photon diffusion equation (Kompaneets equation) for RCS is derived. The
photon system is modeled three dimensionally. Numerical calculations show that
there exist not only up scattering but also down scattering of RCS, depending
on the parameter space. RCS's possible applications to the spectra energy
distributions of magnetar candidates and radio quiet isolated neutron stars
(INSs) are point out. The optical/UV excess of INSs may caused by the down
scattering of RCS. The calculations for RX J1856.5-3754 and RX J0720.4-3125 are
presented and compared with their observational data. In our model, the INSs
are proposed to be normal neutron stars, although the quark star hypothesis is
still possible. The low pulsation amplitude of INSs is a natural consequence in
the RCS model.Comment: 16 pages, 5 figures, 2 tables, accepted for publication in RA