Substructure of Visibility Functions from Scattered Radio Emission of Pulsars through Space VLBI

Попов, М. В.; Bartel, N.; Burgin, M. S.; Gwinn, C. R.; Smirnova, T. V.; Soglasnov, V. A.

doi:10.3847/1538-4357/ab5db6

Cited by 11 publications

(7 citation statements)

References 19 publications

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“…Space VLBI with Radioastron revealed for some pulsars that the tail of the delay cross-section of V (τ, t) retained significant magnitudes at baseline projections where the pulsar scattering disk was completely resolved. The delay cross-section, ACF (∆τ, ∆t = 0) of V (τ, t), was found to be well approximated by a Lorentz function (Popov et al 2020). The Fourier transform of a Lorentz function is a two-sided exponential and therefore the auto-spectrum from our S(f, t) would also be expected to be a two-sided exponential (second row in Table 4).…”

Section: Relation To the Dynamic Visibility Function From Space Vlbi ...mentioning

confidence: 89%

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Electron density variations in the interstellar medium and the average frequency profile of a scintle from pulsar scintillation spectra

Bartel¹,

Burgin²,

Fadeev³

et al. 2022

Preprint

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We observed the scintillation pattern of nine bright pulsars at 324 MHz and three at 1.68 GHz and analyzed the wavenumber spectrum which is related to electron density variations of the plasma turbulence of the interstellar medium. For all pulsars the frequency section of the autocorrelation function of the dynamic spectra to at least 45% of the maximum corresponds to predictions of scattering theories with a range of power-law exponents of the wavenumber spectrum of 3.56 ≤ α ≤ 3.97 with errors ≤ 0.05 and a mean with standard deviation of 3.76 ± 0.13. The range includes α = 3.67 for the Kolmogorov spectrum. Similar results although with larger errors were found from the Fourier transform of the autocorrelation functions down to ∼ 10 −3 of the maximum. No clear case of a distinction between thin-screen and extended-medium scattering models was found. The average frequency profile of the scintles can be characterized for steep wavenumber spectra with α 4 by a cusp with a somewhat rounded peak. For flatter spectra, down to at least α ∼ 3.56 the cusp with its peak becomes more pronounced and its decay steepens. We discuss our findings in the context of scattering characteristics of the interstellar medium.

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Section: Relation To the Dynamic Visibility Function From Space Vlbi ...mentioning

confidence: 89%

“…Previously we reported on a comparison of θ sc and τ sc and our estimates of the distances to the effective scattering screens (Gwinn et al 2016;Fadeev et al 2018;Popov et al 2017Popov et al , 2020, as well as on the time characteristics of the scintillation pattern .…”

Section: Introductionmentioning

confidence: 98%

Electron density variations in the interstellar medium and the average frequency profile of a scintle from pulsar scintillation spectra

Bartel¹,

Burgin²,

Fadeev³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Previously we reported on a comparison of θ sc and τ sc and our estimates of the distances to the effective scattering screens (Gwinn et al 2016;Popov et al 2017Popov et al , 2020Fadeev et al 2018), as well as on the time characteristics of the scintillation pattern .…”

Section: Introductionmentioning

confidence: 98%

Electron Density Variations in the Interstellar Medium and the Average Frequency Profile of a Scintle from Pulsar Scintillation Spectra

Bartel

Burgin

Fadeev

et al. 2022

ApJ

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We observed the scintillation pattern of nine bright pulsars at 324 MHz and three at 1.68 GHz and analyzed the wavenumber spectrum, which is related to electron density variations of the plasma turbulence of the interstellar medium (ISM). For all pulsars the frequency section of the autocorrelation function (ACF) of the dynamic spectra to at least 45% of the maximum corresponds to predictions of scattering theories with a range of power-law exponents of the wavenumber spectrum of 3.56 ≤ α ≤ 3.97 with errors ≤0.05 and a mean with standard deviation of 3.76 ± 0.13. The range includes α = 3.67 for the Kolmogorov spectrum. Similar results, although with larger errors, were found from the Fourier transform of the ACFs down to ∼10−3 of the maximum. No clear case of a distinction between thin-screen and extended-medium scattering models was found. The average frequency profile of the scintles can be characterized for steep wavenumber spectra with α ≲ 4 by a cusp with a somewhat rounded peak. For flatter spectra, down to at least α ∼ 3.56 the cusp with its peak becomes more pronounced and its decay steepens. We discuss our findings in the context of the scattering characteristics of the ISM.

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“…These studies were mainly aimed at the properties and spatial distribution of interstellar plasma. The distances to effective scattering screens were determined by comparing the angular broadening with the characteristic time of the pulse scattering [6][7][8][9]. The pulsars selected for our study and their parameters are listed in Table 1.…”

Section: Introductionmentioning

confidence: 99%

The Spectrum Power of Interstellar Plasma Inhomogeneities in the Direction of Eleven Radio Pulsars

Попов

Smirnova

2021

Astron. Rep.

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We have analyzed two-dimensional correlation functions from the dynamic spectra of 11 pulsars using the archival data of the “Radioastron” project. The time-sections of these functions were approximated by exponential functions with a power $$\alpha $$. It is shown that this approximation describes the shape of the correlation function much better than the Gaussian. The temporal structure function $$D(\Delta t)$$ for small values of the delay $$\Delta t$$is a power law with an index $$\alpha $$. The spectrum power of spatial inhomogeneities of the interstellar plasma is related to the power of the structure function as $$n = \alpha + 2$$. We have determined the characteristic scintillation time and the power $$n$$ in the direction of 11 pulsars. In the direction of three pulsars (B0329+54, B0823+26, and B1929+10), the spectrum power of spatial inhomogeneities of the interstellar plasma turned out to be very close to the value for the Kolmogorov spectrum ($$n = 3.67$$). For other pulsars, it ranges from 3.18 to 3.86. It is shown that the measured scintillation parameters are significantly influenced by the duration of the observation session, expressed by its ratio to the characteristic scintillation time. If this parameter is less than 10, the parameter estimates may be biased: the values of $$\alpha $$ and the characteristic scintillation time $${{t}_{{{\text{scint}}}}}$$ may decrease.

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Substructure of Visibility Functions from Scattered Radio Emission of Pulsars through Space VLBI

Cited by 11 publications

References 19 publications

Electron density variations in the interstellar medium and the average frequency profile of a scintle from pulsar scintillation spectra

Electron density variations in the interstellar medium and the average frequency profile of a scintle from pulsar scintillation spectra

Electron Density Variations in the Interstellar Medium and the Average Frequency Profile of a Scintle from Pulsar Scintillation Spectra

The Spectrum Power of Interstellar Plasma Inhomogeneities in the Direction of Eleven Radio Pulsars

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