diffraction scintillation at 1.4 and 4.85ghz
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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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
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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.
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Observations• 100m RT in Effelsberg during 2-12th Sept. 2003
• 15 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
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PSR 0329+54 (1.41GHz)• Example of dynamic spectra in the strong
scintillation regime
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PSR 1929+10 (1.4GHz; 7 Sept.)• Example of dynamic spectra in the weak(?) scin.regime
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PSR 1929+10 (1.4GHz)• Scin. data; • ACF time function; • CCF frequency
function; • power spectrum;• structure function
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PSR 2020+28 (1.4GHz)• 03 Sept. - strong scint; 10 Sept. - lensing effect
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PSR 2020+28 (1.4GHz)• Scint. data;
• ACF time function;
• CCF frequency function;
• power spectrum
• structure function
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PSR 1642-03 (4.85GHz)• Dynamic spectra in the weak scin. regime
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PSR 0355+54 (4.85GHz)• Dynamic spectra in the strong(?) scin.regime
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PSR 0355+54• Scint. data;• ACF time function• CCF frequency
function• Power spectrum• Structure function
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Number of pulsars
Freq Dec.time Dec.band. Spectrum Str.funct.
1.4GHz 11 8 11(2.7+-0.4) 11(1.5+-0.3)4.85GHz 5 1 5(2.8+-0.4) 5(1.2+-0.4)
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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