Measurement of Radio Emission Scattering Parameters in the Direction of Pulsars B0809+74, B0919+06, and B1133+16 with Ground-Space Interferometer RadioAstron

Abstract

We present the analysis of observations of three pulsars at a frequency of 327 MHz with the ground-space interferometer RadioAstron. The main scintillation parameters were measured: the decorrelation bandwidth \(\Delta {{f}_{{{\text{dif}}}}}\) and the scintillation time \(\Delta {{t}_{{{\text{dif}}}}}\). We have found that these parameters vary significantly over time. For PSR B1133+16, the decorrelation bandwidth \(\Delta {{f}_{{{\text{dif}}}}}\) varied from 100 to 350 kHz for the period of 2014 to 2018. For PSR B0919+06 \(\Delta {{f}_{{{\text{dif}}}}}\) varied from 36 to 195 kHz over approximately the same time period. In the direction of the observed pulsars, the power-law indices for the spatial inhomogeneity spectrum of the scattering plasma were estimated. The characteristic frequency and time scales of the diffractive scintillations for PSR B0809+74 are comparable to the receiver bandwidth and observation time, respectively. Therefore, only a lower limit for \(n\) can be obtained for this pulsar. The mean value is \(n = 3.40 \pm 0.11\) for PSR B1133+16 and \(n = 3.90 \pm 0.04\) for PSR B0919+06. We have also measured the angular diameter of the average scattering disks, \({{\theta }_{{\text{H}}}}\), for these two pulsars. For PSR B0919+06, \({{\theta }_{{\text{H}}}} = 26{\kern 1pt} - {\kern 1pt} 28\) mas, and for B1133+16, \({{\theta }_{{\text{H}}}} = 12.0 \pm \) 1.6 mas. We provide the estimates of the distance to the scattering screens. All measured parameters have been compared with previously published data.