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ABSTRACT Observations of pulsar scintillation are among the few astrophysical probes of very small-scale (≲ 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 overpressurized plasma in local ISM inhomogeneities, such as supernova remnants, H ii regions, and bow shocks. Here we present a survey of eight pulsars conducted at the Five-hundred-metre 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 $$\sim 90~{{\ \rm per\ cent}}$$ 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 ∼105 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.
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A Scintillation Arc Survey of 22 Pulsars with Low to Moderate Dispersion Measures
Abstract Context.By providing information about the location of scattering material along the line of sight (LoS) to pulsars, scintillation arcs are a powerful tool for exploring the distribution of ionized material in the interstellar medium (ISM). Here, we present observations that probe the ionized ISM on scales of ∼0.001–30 au.Aims.We have surveyed pulsars for scintillation arcs in a relatively unbiased sample with DM < 100 pc cm−3. We present multifrequency observations of 22 low to moderate DM pulsars. Many of the 54 observations were also observed at another frequency within a few days.Methods.For all observations, we present dynamic spectra, autocorrelation functions, and secondary spectra. We analyze these data products to obtain scintillation bandwidths, pulse broadening times, and arc curvatures.Results.We detect definite or probable scintillation arcs in 19 of the 22 pulsars and 34 of the 54 observations, showing that scintillation arcs are a prevalent phenomenon. The arcs are better defined in low DM pulsars. We show that well-defined arcs do not directly imply anisotropy of scattering. Only the presence of reverse arclets and a deep valley along the delay axis, which occurs in about 20% of the pulsars in the sample, indicates substantial anisotropy of scattering.Conclusions.The survey demonstrates substantial patchiness of the ionized ISM on both astronomical-unit-size scales transverse to the LoS and on ∼100 pc scales along it. We see little evidence for distributed scattering along most lines of sight in the survey.
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- PAR ID:
- 10384799
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 941
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 34
- Size(s):
- Article No. 34
- Sponsoring Org:
- National Science Foundation
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