Constraint on pulsar wind properties from induced Compton scattering off radio pulses

• Published in: Progress of theoretical and experimental physics 2013-12, Vol.2013 (12), p.123-123E01
• Main Authors: Tanaka, Shuta J., Takahara, Fumio
• Format: Article
• Language: English
• ISSN: 2050-3911; 2050-3911
• DOI: 10.1093/ptep/ptt108

Pulsar winds have longstanding problems in energy conversion and pair cascade processes, which determine the magnetization , the pair multiplicity , and the bulk Lorentz factor of the wind. We study induced Compton scattering by a relativistically moving cold plasma to constrain the wind properties by imposing that radio pulses from the pulsar itself are not scattered by the wind, as was first studied by Wilson and Rees [D. B. Wilson and M. J. Rees, Mon. Not. R. Astron. Soc., 185, 297 (1978)]. We find that relativistic effects cause a significant increase or decrease of the scattering coefficient depending on scattering geometry. Applying this to the Crab, we consider the uncertainties of the inclination angle of the wind velocity with respect to the radio beam and the emission region size , which determines the opening angle of the radio beam. We obtain the lower limit (  cm) at the light cylinder for an inclined wind 10^{-2.7}$]]> . For an aligned wind , we require 10^{2.7}$]]> at and an additional constraint 10^{3.4}r^{1/5}_{{\mathrm {e}},3}(1+\sigma)^{-1/10}$]]> at the characteristic scattering radius  cm, within which the 'lack of time' effect prevents scattering. Considering the lower limit suggested by recent studies of the Crab Nebula, for  cm, we obtain the most optimistic constraint and , which are independent of when and at .