Diffraction scintillation at 1.4 and 4.85GHz V.M.Malofeev, O.I.Malov, S.A.Tyul’bashev PRAO, Russia W.Sieber Hochschule Nederrhein, Germany A.Jessner, R.Wielebinski MPIfR, Germany
Introduction Most important characteristic of the turbulent interstellar medium is the three-dimensional spatial spectrum of the electron density fluctuations: a Gaussian or power law. The aim of our project was to obtain the form of turbulence spectrum for different regions of the sky and for pulsars which are at different distances.
Observations 100m RT in Effelsberg during 2-12th Sept pulsars at 1.4GHz and 6 at 4.85GHz Criteria: strong objects with good SNR, pulsars should clearly show scintillation to obtain dynamic spectra the total receiver bandwidht must be much broader then the decorrelation bandwidth of pulsars 1.4GHz: 30chan x 1.33MHz= 40MHz 4.85GHz: 8chan x 60MHz=480MHz two polarization; flux measurements every 30sec; duration of observations 1-10hours
PSR (1.41GHz) Example of dynamic spectra in the strong scintillation regime
PSR (1.4GHz; 7 Sept.) Example of dynamic spectra in the weak(?) scin.regime
PSR (1.4GHz) Scin. data; ACF time function; CCF frequency function; power spectrum; structure function
PSR (1.4GHz) 03 Sept. - strong scint; 10 Sept. - lensing effect
PSR (1.4GHz) Scint. data; ACF time function; CCF frequency function; power spectrum structure function
PSR (4.85GHz) Dynamic spectra in the weak scin. regime
PSR (4.85GHz) Dynamic spectra in the strong(?) scin.regime
PSR Scint. data; ACF time function CCF frequency function Power spectrum Structure function
Number of pulsars
Conclusion We have obtained scintillation data for 11 PSR at 1.4GHz and 5 PSR at 4.85GHz: the decorrelation time and bandwidth, power low index for spectra and structure function Possible lensing effect (focal spot effect) have been detected for a few pulsars near the critical frequency