Synchrotron spectra of short-period pulsars

A model with synchrotron radiation near the light cylinder is proposed to e xplain the observed spectra of short-period pulsars (P less than or equal t o 0.1 s). These spectra can be described if a power-law energy distribution of the emitting electrons with exponent gamma = 2-8 is assumed. For most p ulsars, the peak frequency nu (m) is below 10 MHz. The v(m)(gamma) dependen ce is derived, and shows that the peak frequencies for pulsars with spectra l indices alpha < 1.5 may fall in the observable range. In particular, <nu> (m) may be nu (m) similar to 100 MHz for PSR J0751 + 1807 and PSR J1640 + 2 224. The observed radio spectrum of Geminga (PSR J0633 + 1746) can be descr ibed by a synchrotron model with a monoenergetic or Maxwellian distribution of relativistic electrons and a small angle beta between the spin axis and magnetic moment (beta similar to 10 degrees). (C) 2001 MAIK "Nauka/Interpe riodica".