Pulsar Scintillation through Thick and Thin: Bow Shocks, Bubbles, and the Broader Interstellar Medium

TL;DR

This study uses high-sensitivity FAST observations of eight pulsars to analyze scintillation arcs, revealing diverse characteristics and providing insights into small-scale structures and turbulence in the interstellar medium.

Contribution

The paper presents a comprehensive survey of pulsar scintillation arcs with unprecedented sensitivity, uncovering more arcs and detailed scattering media insights than previous studies.

Findings

Multiple scintillation arcs observed per pulsar, indicating complex scattering structures.

Some arcs suggest scattering near the pulsar, with low curvature and truncation.

Screen distances vary widely, including very close to the pulsar or observer.

Abstract

Observations of pulsar scintillation are among the few astrophysical probes of very small-scale ($\lesssim$ au) phenomena in the interstellar medium (ISM). In particular, characterization of scintillation arcs, including their curvature and intensity distributions, can be related to interstellar turbulence and potentially over-pressurized plasma in local ISM inhomogeneities, such as supernova remnants, HII regions, and bow shocks. Here we present a survey of eight pulsars conducted at the Five-hundred-meter Aperture Spherical Telescope (FAST), revealing a diverse range of scintillation arc characteristics at high sensitivity. These observations reveal more arcs than measured previously for our sample. At least nine arcs are observed toward B1929$+$10 at screen distances spanning $\sim 90\%$ of the pulsar's $361$ pc path-length to the observer. Four arcs are observed toward B0355$+$54, with one arc yielding a screen distance as close as $\sim10^5$ au ($<1$ pc) from either the pulsar or the observer. Several pulsars show highly truncated, low-curvature arcs that may be attributable to scattering near the pulsar. The scattering screen constraints are synthesized with continuum maps of the local ISM and other well-characterized pulsar scintillation arcs, yielding a three-dimensional view of the scattering media in context.