The structure function of PSRB0950+08 scintilations: the fingerprints of an extremely thin ionized scattering screen in the local ISM

TYPEAstrophysics Seminar
Speaker:Itzhak Goldman
Affiliation:Tel Aviv University
Time:14:30 - 15:30
Location:Lidow 620
Abstract:The structure function of the observed scintillations time-lags of the arrival times of the pulses from PSRB0950+08 were fitted by the observers to a power law with index of ~ 1. This is an appreciable deviation from 1.67, usually observed in scintillation data and which is consistent with a Kolmogorov turbulent ionized medium. Since the lateral spatial scales probed by the observations are small, one would expect a Kolmogorov spectrum. We suggest a more conservative interpretation of the observations: that the turbulence is indeed a Kolmogorov turbulence and that the apparent deviation is due to a geometrical effect: a turbulent region with depth which is comparable to the observed lateral scales on the plane of the sky. A best fit is obtained for a turbulent region with depth of (4.2 ± 0.8)×10^8 cm. The existence of extremely thin, ionized scattering screens within the local ISM, has been suggested by Linsky etal (2008). The present analysis adds support to this suggestion.