High Resolution VLBI Astrometry of pulsar scintillation screens with the $\theta-\theta$ Transform

TL;DR

This paper advances pulsar scintillometry by extending the $ heta- heta$ technique with interferometric visibilities, enabling high-resolution imaging of scattering media and precise measurements of pulsar scintillation screens.

Contribution

It introduces an interferometric extension to the $ heta- heta$ method, improving calibration and measurement precision in pulsar scintillation studies.

Findings

Measured effective screen distance with five times greater precision.

Determined lens orientation more accurately than previous methods.

Enhanced high-resolution imaging of scattering media.

Abstract

The recent development of $\theta\mhyphen\theta$ techniques in pulsar scintillometry has opened the door for new high resolution imaging techniques of the scattering medium. By solving the phase retrieval problem and recovering the wavefield from a pulsar dynamic spectrum, the Doppler shift, time delay, and phase offset of individual images can be determined. However, the results of phase retrieval from a single dish are only known up to a constant phase rotation, which introduces extra parameters when doing astrometry using Very Long Baseline Interferometry. We present an extension to previous $\theta\mhyphen\theta$ methods using the interferometric visibilities between multiple stations to calibrate the wavefields. When applied to existing data for PSR B0834+06 we measure the effective screen distance and lens orientation with five times greater precision than previous works.