Discriminate between anisotropic and isotropic scattering-screen geometries

Determine whether the M53A scattering screen is described by a one-dimensional anisotropic thin-screen geometry or a two-dimensional isotropic thin-screen geometry.

Background

The scintillation-arc curvature of the globular-cluster pulsar M53A was modeled using two limiting thin-screen geometries: a one-dimensional anisotropic screen and a two-dimensional isotropic screen. These models yield different screen-distance estimates, although both place the screen at an unusually large Galactic height.

The available multi-epoch FAST observations have low signal-to-noise ratios and provide only a limited number of reliable curvature measurements. Consequently, the observations do not establish which of the two geometries more accurately represents the physical scattering structure, leaving the geometry—and therefore the detailed interpretation of the inferred screen properties—unresolved. The same unresolved distinction is reiterated in Appendix B.