Small-scale solar wind density turbulence spectrum from interplanetary scintillation observations

The method of determining the angular sizes of compact radio sources and parameters of the plasma turbulence using temporal scintillation power spectra is described and tested. The observations were carried out with the radio telescope BSA of Lebedev Physical Institute at the frequency 111 MHz. Estimates of the angular size and the turbulence parameters are obtained for the strong scintillating source 3C 48 observed during April-May of 2007-2009. During these periods the interplanetary plasma was comparatively quiet

Changes in the spectral index of the interplanetary plasma turbulence in the period of low solar activity from observations of strongly scintillating source 3C 298

We present the results of the analysis of temporal power spectra of interplanetary scintillation for the strong radio source 3C 298 observed at 111 MHz with radio telescope BSA LPI in the period near the solar activity minimum. The velocity of the solar wind plasma irregularities and the power exponent of the turbulence spatial spectrum are estimated from the measured temporal scintillation spectra. It is shown that some high frequency ffattening of the temporal scintillation power spectra due to the noise influence can bias the estimates of the source angular size and the spectral index of plasma turbulence. The comparison between the turbulence parameters for the sources 3C 48 and 3C 298 have been carried out. The decrease in the turbulence spectral exponent by transit from the high latitude fast solar wind to the low latitude slow solar wind is found from the 3C 298 data that confirms similar dependence found recently for the 3C 48 data

Turbulence induced additional deceleration in relativistic shock wave propagation: implications for gamma-ray burst

The late afterglow of gamma-ray burst is believed to be due to progressive deceleration of the forward shock wave driven by the gamma-ray burst ejecta propagating in the interstellar medium. We study the dynamic effect of interstellar turbulence on shock wave propagation. It is shown that the shock wave decelerates more quickly than previously assumed without the turbulence. As an observational consequence, an earlier jet break will appear in the light curve of the forward shock wave. The scatter of the jet-corrected energy release for gamma-ray burst, inferred from the jet-break, may be partly due to the physical uncertainties in the turbulence/shock wave interaction. This uncertainties also exist in two shell collisions in the well-known internal shock model proposed for gamma-ray burst prompt emission. The large scatters of known luminosity relations of gamma-ray burst may be intrinsic and thus gamma-ray burst is not a good standard candle. We also discuss the other implications.Comment: accepted for publication in Astrophysics and Space Scienc

Search for and detection of pulsars inmonitoring observations at 111 MHz

In the course of monitoring interplanetary scintillations of a large number of sources using the Big Scanning Antenna of the Lebedev Physical Institute, a search for pulsars with periods ≥0.4 s at declinations −9◦ < δ < 42◦ and right ascensions 0h < α < 24h was simultaneously carried out. The search was conducted using four years of observations carried out at 110.25MHz in six frequency channels making up a 2.5 MHz band and having a time resolution of 100 ms. The initial identification of pulsar candidates was done using Fourier power spectra averaged over the entire observational period; the pulsar candidates were then verified using observations with higher frequency and time resolution: 32 frequency channels and a time resolution of 12.5 ms. Eighteen new pulsars were discovered in the studied area, whose main characteristics are presented