Scintillation of PSR B1508+55 -- the view from a 10,000-km baseline

Marthi, V. R.; Simard, D.; Main, R. A.; Pen, U. -L.; van Kerkwijk, M. H.; Vanderlinde, K.; Gupta, Y.; Roberts, C.; Quine, B. M.

doi:10.48550/arxiv.2010.09723

“…The inverted arclets arise from mutual interference between the scattered images, and their sharpness is a signature of highly anisotropic scattering, where the scattered images of the pulsar lie along a (nearly) straight line (Walker et al 2004). Like in previous observations, we find that the arclets move along the scintillation arc at a constant speed for long periods of time (Hill et al 2005;Marthi et al 2020). This implies that the scattered images giving rise to the arclets must arise from a large group of parallel and elongated structures in the scattering screen, e.g., turbulence elongated along a given direction (Goldreich & Sridhar 1995), waves on a plasma sheet seen in projection as folds (Romani et al 1987;Pen & Levin 2014), or magnetic noodles of plasma stabilized by reconnection (Gwinn 2019).…”

Section: Observation and Pulsar Scintillationsupporting

confidence: 80%

Pulsar Double Lensing Sheds Light on the Origin of Extreme Scattering Events

Zhu

¹

,

Baker

²

,

Pen

³

et al. 2023

ApJ

View full text Add to dashboard Cite

In extreme scattering events, the brightness of a compact radio source drops significantly, as light is refracted out of the line of sight by foreground plasma lenses. Despite recent efforts, the nature of these lenses has remained a puzzle, because any roughly round lens would be so highly overpressurized relative to the interstellar medium that it could only exist for about a year. This, combined with a lack of constraints on distances and velocities, has led to a plethora of theoretical models. We present observations of a dramatic double-lensing event in pulsar PSR B0834+06 and use a novel phase-retrieval technique to show that the data can be reproduced remarkably well with a two-screen model: one screen with many small lenses and another with a single, strong one. We further show that the latter lens is so strong that it would inevitably cause extreme scattering events. Our observations show that the lens moves slowly and is highly elongated on the sky. If similarly elongated along the line of sight, as would arise naturally from a sheet of plasma viewed nearly edge-on, no large overpressure is required and hence the lens could be long-lived.

show abstract

“…The inverted arclets arise from mutual interference between the scattered images, and their sharpness is a signature of highly anisotropic scattering, where the scattered images of the pulsar lie along a (nearly) straight line (Walker et al 2004). Like in previous observations, we find that the arclets move along the scintillation arc at a constant speed for long periods of time (Hill et al 2005;Marthi et al 2020). This implies that the scattered images giving rise to the arclets must arise from a large group of parallel and elongated structures in the scattering screen, e.g., turbulence elongated along a given direction (Goldreich & Sridhar 1995), waves on a plasma sheet seen in projection as folds (Romani et al 1987;Pen & Levin 2014), or magnetic noodles of plasma stabilized by reconnection (Gwinn 2019).…”

Section: Observation and Pulsar Scintillationsupporting

confidence: 80%

Pulsar Double-lensing Sheds Light on the Origin of Extreme Scattering Events

Zhu¹,

Baker²,

Pen³

et al. 2022

Preprint

0

View full text Add to dashboard Cite

In extreme scattering events, the brightness of a compact radio source drops significantly, as light is refracted out of the line of sight by foreground plasma lenses. Despite recent efforts, the nature of these lenses has remained a puzzle, because any roughly round lens would be so highly overpressurized relative to the interstellar medium that it could only exist for about a year. This, combined with a lack of constraints on distances and velocities, has led to a plethora of theoretical models. We present observations of a dramatic double-lensing event in pulsar PSR B0834+06 and use a novel phase-retrieval technique to show that the data can be reproduced remarkably well with a two-screen model: one screen with many small lenses and another with a single, strong one. We further show that the latter lens is so strong that it would inevitably cause extreme scattering events. Our observations show that the lens moves slowly and is highly elongated on the sky. If similarly elongated along the line of sight, as would arise naturally from a sheet of plasma viewed nearly edge-on, no large overpressure is required and hence the lens could be long-lived. Our new technique opens up the possibility of probing interstellar plasma structures in detail, leading to understanding crucial for high-precision pulsar timing and the subsequent detection of gravitational waves.

show abstract

“…Generally, DM events are more likely to be detected if the scattering/lensing direction is closely aligned with the pulsar's motion (c.f. scattering and proper motion alignment in PSR B1508+55, Wucknitz 2019; Marthi et al 2020).…”

Section: Mjdmentioning

confidence: 99%

Profile changes associated with DM events in PSR J1713+0747

Lin,

Luo

et al. 2021

Preprint

View full text Add to dashboard Cite

Propagation effects in the interstellar medium and intrinsic profile changes can cause variability in the timing of pulsars, which limits the accuracy of fundamental science done via pulsar timing. One of the best timing pulsars, PSR J1713+0747, has gone through two "dip" events in its dispersion measure time series. If these events reflect real changes in electron column density, they should lead to multiple imaging. We show that the events are are well-fit by an underdense corrugated sheet model, and look for associated variability in the pulse profile using principal component analysis. We find that there are transient pulse profile variations, but they vary in concert with the dispersion measure, unlike what is expected from lensing due to a corrugated sheet. The change is consistent in shape across profiles from both the Greenbank and Arecibo radio observatories, and its amplitude appears to be achromatic across the 820 MHz, 1.4 GHz, and 2.3 GHz bands, again unlike expected from interference between lensed images. This result is puzzling. We note that some of the predicted lensing effects would need higher time and frequency resolution data than used in this analysis. Future events appear likely, and storing baseband data or keeping multiple time-frequency resolutions will allow more in-depth study of propagation effects and hence improvements to pulsar timing accuracy.

show abstract

Scintillation of PSR B1508+55 -- the view from a 10,000-km baseline

Cited by 3 publications

References 30 publications

Pulsar Double Lensing Sheds Light on the Origin of Extreme Scattering Events

Pulsar Double Lensing Sheds Light on the Origin of Extreme Scattering Events

Pulsar Double-lensing Sheds Light on the Origin of Extreme Scattering Events

Profile changes associated with DM events in PSR J1713+0747

Contact Info

Product

Resources

About