Astronomy & Astrophysics Seminar: The structure function of PSRB0950+08 scintilations: the fingerprints of an extremely thin ionized scattering screen

Abstract:

The structure function of the scintillations time-lags of the arrival time of the pulses from PSRB0950+08 was fitted by the observers to a power law with index of∼ 1. This is an appreciable deviation from an index of 1.67, usually observed in scintillation data and which is consistent with a Kolmogorov turbulent ionized medium. It has been suggested that the observations imply a need to revise the current understanding of interstellar turbulence. 
We suggest a more conservative interpretation: that the turbulence is a Kol- mogorov 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. 
A best fit is obtained for a turbulent region with depth of 4.2 ± 0.8 × 108cm. The existence of extremely thin, ionized scattering screens in the local ISM, has been suggested by originally by Linsky etal (2008)(followed by papaers untill the present) who mapped the 3D velocities of the local ISM. The scintillations measurements lend an independent support to the existence of these screens.

Seminar Organizer: Prof. Sara Beck