Scintillation Arcs in Low-Frequency Observations of the Timing-Array Millisecond Pulsar PSR J0437–4715

Bhat, N. D. R.; Ord, S. M.; Tremblay, S. E.; McSweeney, S. J.; Tingay, S. J.

doi:10.3847/0004-637x/818/1/86

Cited by 56 publications

(69 citation statements)

References 41 publications

(54 reference statements)

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“…First results, published in the paper of Smirnova et al (2014) show that a layer of plasma located very close to the Earth, at 4.4 to 16.4 pc, is primarily responsible for scintillation of B0950+08. First indications that the nearest interstellar medium is responsible for the scintillations of pulsars B0950+08 and J0437-47 were discussed in earlier papers Smirnova & Shishov (2008); Smirnova et al (2006); see also Bhat et al (2016). These pulsars have among the lowest dispersion measures observed, indicating a low column density of plasma.…”

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confidence: 88%

Interstellar scintillations of PSR B1919+21: space–ground interferometry

Shishov

Smirnova

Gwinn

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We carried out observations of pulsar PSR B1919+21 at 324 MHz to study the distribution of interstellar plasma in the direction of this pulsar. We used the RadioAstron (RA) space radiotelescope together with two ground telescopes: Westerbork (WB) and Green Bank (GB). The maximum baseline projection for the space-ground interferometer was about 60000 km. We show that interstellar scintillation of this pulsar consists of two components: diffractive scintillations from inhomogeneities in a layer of turbulent plasma at a distance z 1 = 440 pc from the observer or homogeneously distributed scattering material to pulsar; and weak scintillations from a screen located near the observer at z 2 = 0.14 ± 0.05 pc. Furthermore, in the direction to the pulsar we detected a prism that deflects radiation, leading to a shift of observed source position. We show that the influence of the ionosphere can be ignored for the space-ground baseline. Analysis of the spatial coherence function for the space-ground baseline (RA-GB) yielded the scattering angle in the observer plane: θ scat = 0.7 mas. An analysis of the time-frequency correlation function for weak scintillations yielded the angle of refraction in the direction to the pulsar: θ ref,0 = 110 ms and the distance to the prism z prism ≤ 2 pc.

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mentioning

confidence: 88%

Interstellar scintillations of PSR B1919+21: space–ground interferometry

Shishov

Smirnova

Gwinn

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…a 256-tile array extending out to ∼ 6 km (Wayth et al 2018). With its voltage capture system (VCS; Tremblay et al 2015), which records data at 10-kHz/100-µs resolutions, the MWA has been producing a wide variety of pulsar science (e.g., McSweeney et al 2017;Meyers et al 2017;Xue et al 2017), including characterization of the ISM towards important southern-sky PTA targets (e.g., Bhat et al 2014Bhat et al , 2016Bhat et al , 2018.…”

Section: Introductionmentioning

confidence: 99%

A High Time-resolution Study of the Millisecond Pulsar J2241−5236 at Frequencies Below 300 MHz

Kaur

Bhat

Tremblay

et al. 2019

ApJ

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One of the major challenges for pulsar timing array (PTA) experiments is the mitigation of the effects of the turbulent interstellar medium (ISM) from timing data. These can potentially lead to measurable delays and/or distortions in the pulse profiles and scale strongly with the inverse of the radio frequency. Low-frequency observations are therefore highly appealing for characterizing them. However, in order to achieve the necessary time resolution to resolve profile features of short-period millisecond pulsars, phase-coherent de-dispersion is essential, especially at frequencies below 300 MHz. We present the lowest-frequency (80-220 MHz), coherently de-dispersed detections of one of the most promising pulsars for current and future PTAs, PSR J2241−5236, using our new beam-former software for the MWA's voltage capture system (VCS), which reconstructs the time series at a much higher time resolution of ∼ 1 µs by re-synthesizing the recorded voltage data at 10-kHz/100-µs native resolutions. Our data reveal a dual-precursor type feature in the pulse profile that is either faint or absent in highfrequency observations from Parkes. The resultant high-fidelity detections have enabled dispersion measure (DM) determinations with very high precision, of the order of (2-6) × 10 −6 pc cm −3 , owing to the microsecond level timing achievable for this pulsar at the MWA's low frequencies. This underscores the usefulness of low-frequency observations for probing the ISM toward PTA pulsars and informing optimal observing strategies for PTA experiments.

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“…The incoherent beamformer has already been used to study the properties and population of pulsars with the MWA (Xue et al 2017). The coherent beamformer is also beginning to be employed (Bhat et al 2016;McSweeney et al 2017;Bhat et al 2018) and is undergoing a process of indicating that the sky temperature of this pointing considerably exceeds the receiver temperature at this frequency. The polarimetric profile is consistent with that published in Johnston et al (2008).…”

Section: Applying Delay and Gain Compensationmentioning

confidence: 99%

MWA tied-array processing I: Calibration and beamformation

Ord

Tremblay

McSweeney

et al. 2019

Publ. Astron. Soc. Aust.

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The Murchison Widefield Array is a low-frequency Square Kilometre Array precursor located at the Murchison Radioastronomy Observatory in Western Australia. Primarily designed as an imaging telescope, but with a flexible signal path, the capabilities of this telescope have recently been extended to include off-line incoherent and tied-array beam formation using recorded antenna voltages. This has provided the capability for high-time and frequency resolution observations, including a pulsar science program. This paper describes the algorithms and pipeline that we have developed to form the tied array beam products from the summation of calibrated signals of the antenna elements, and presents example polarimetric profiles for PSRs J0437−4715 and J1900−2600 at 185 MHz.

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Scintillation Arcs in Low-Frequency Observations of the Timing-Array Millisecond Pulsar PSR J0437–4715

Cited by 56 publications

References 41 publications

Interstellar scintillations of PSR B1919+21: space–ground interferometry

Interstellar scintillations of PSR B1919+21: space–ground interferometry

A High Time-resolution Study of the Millisecond Pulsar J2241−5236 at Frequencies Below 300 MHz

MWA tied-array processing I: Calibration and beamformation

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