Revealing compact structures of interstellar plasma in the Galaxy with RadioAstron

Fadeev, E. N.; Andrianov, A. S.; Burgin, M. S.; Попов, М. В.; Rudnitskiy, A. G.; Shishov, V. I.; Smirnova, T. V.; Zuga, V. A.

doi:10.1093/mnras/sty2055

Cited by 27 publications

(31 citation statements)

References 51 publications

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“…Parallel noodles are also in accord with interferometric observations showing highly anisotropic structures. Misaligned noodles introduce wider structures if randomly oriented, and multiple arcs or off-arc features if not, as I discuss in Section 5; indeed a wide variety of such structure are observed (Fadeev et al 2018). In reconnection sheets in particular, one expects cohorts of magnetic field lines with different orientations.…”

Section: Proposed Interpretation: Magnetic Noodlesmentioning

confidence: 96%

Noodle model for scintillation arcs

Gwinn

2019

Monthly Notices of the Royal Astronomical Society

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I show that narrow, parallel strips of phase-changing material, or "noodles," generically produce parabolic structures in the delay-rate domain. Such structures are observed as "scintillation arcs" for many pulsars. The model assumes the strips have widths of a few Fresnel zones or less, and are much longer than they are wide. I use the Kirchhoff integral to find the scattered field. Along the strips, integration leads to a stationary-phase point where the strip is closest to the line of sight. Across the strip, the integral leads to a 1D Fourier transform. In the limit of narrow bandwidth and short integration time, the integral reproduces the observed scintillation arcs and secondary arclets. The set of scattered paths follows the pulsar as it moves. Cohorts of noodles parallel to different axes produce multiple arcs, as often observed. A single strip canted with respect to the rest produces features off the main arc. I present calculations for unrestricted frequency ranges and integration times; behavior of the arcs matches that observed, and can blur the arcs. Physically, the noodles may correspond to filaments or sheets of over-or under-dense plasma, with a normal perpendicular to the line of sight. The noodles may lie along parallel magnetic field lines that carry density fluctuations, perhaps in reconnection sheets. If so, observations of scintillation arcs would allow visualization of magnetic fields in reconnection regions.

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Section: Proposed Interpretation: Magnetic Noodlesmentioning

confidence: 96%

Noodle model for scintillation arcs

Gwinn

2019

Monthly Notices of the Royal Astronomical Society

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“…Our pulsars B0329+54, B0823+26, B0834+06 and B1933+16 are all undergoing isotropic scattering. Their galactic coordinates and the relative distances of their scattering screens (see , Table 1) indicate that for the first three pulsars the screens are approximately associated with the Local Arm in our Galaxy and for B1933+16 with the Carina Sagittarius Arm (see also , Fadeev et al (2018); Popov et al (2017)). Despite the large range of their distances, D, dispersion measures, DM , scintillation times, t scint , scattering times, τ sc , (AT-CD)×(HO-CD) CCF RR 5.8-7.5, 9.3 1.1(1) 10.0(2) 0.03 0.05 (AT-CD)×(AT-HO) CCF RR 5.…”

Section: Discussionmentioning

confidence: 90%

“…Assuming a single thin scattering screen and combining, τ sc with θ sc , the distance, d s of the scattering screen relative to the distance, D, of the pulsar could be determined. An analysis of these measurements indicates a possible layered structure of the interstellar plasma in our Galaxy (Fadeev et al 2018; Note-Columns are as follows: (1) pulsar name, (2) pulsar period, (3) dispersion measure, (4) distance, (5) galactic longitude, (6) galactic latitude, (7) observing frequency, (8) scintillation time, (9) scattering time, (10) scattering angle, (11) decorrelation bandwidth, (12) the ratio of distance of the scattering screen to distance of the pulsar, (13) the reference where the parameters in columns (10) to (12) were determined.…”

Section: Introductionmentioning

confidence: 92%

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

Попов

Bartel

Burgin

et al. 2020

ApJ

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We report on the substructure of visibility functions in the delay domain of PSRs B0329+54, B0823+26, B0834+06, B1933+16 and B0833-45 (Vela) observed with earth-earth and RadioAstron space-earth two-element interferometers at frequencies of 324 MHz and 1668 MHz. All visibility functions display unresolved spikes distributed over a range of delays. They are due to band-limited scintillation noise and related to the scattering time. The envelopes for each but the Vela pulsar are well fit by a single Lorentzian which we interpret as being indicative of isotropic scattering on the plane of the sky due to a thin scattering screen between the pulsar and us. In contrast, the envelope for the Vela pulsar needs to be mostly fit by at least two Lorentzians, a narrow and a broad one at the same zero delay. We interpret this characteristic as indicative of anisotropic scattering due to more complex structure of scattering screens in the supernova remnant. The possibility of describing the delay visibility functions by Lorentzians is likely a general property of pulsars and offers a new way of describing scattering parameters of the intervening interstellar medium. Furthermore, for all our pulsars, the unresolved spikes in visibility functions of similar projected baselines were well correlated indicating that the telescopes are located in the same diffraction spot. The correlation vanished for visibilities from largely different baselines, when some radio telescopes are not in the same spot.

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“…We will use the observational data obtained during the implementation of the scientific program of the ground-space interferometer "Radioastron." These data have been used already in other studies [6][7][8]. Dynamic spectra and two-dimensional correlation functions will be analyzed.…”

Section: Introductionmentioning

confidence: 99%

“…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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Revealing compact structures of interstellar plasma in the Galaxy with RadioAstron

Cited by 27 publications

References 51 publications

Noodle model for scintillation arcs

Noodle model for scintillation arcs

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

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

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