Anomalous scattering of pulsars towards the Gum Nebula

TL;DR

This study provides new wideband scatter-broadening measurements of 14 pulsars near the Gum Nebula, revealing a strong correlation between distance and scattering strength and refining the frequency scaling index of scatter-broadening.

Contribution

It significantly increases the measurements of the frequency scaling index of scatter-broadening in the Gum Nebula region and clarifies the scattering origins for the Vela pulsar.

Findings

Strong correlation between pulsar distance and scattering strength.

Refined measurements of the frequency scaling index of scatter-broadening.

Vela pulsar's scattering likely caused by the supernova remnant, not the Gum Nebula.

Abstract

We report wideband scatter-broadening estimates of 14 pulsars towards the Gum nebula region using the Band-3 of the upgraded GMRT. This work increases the measurements of frequency scaling index of scatter-broadening ($\alpha$) across the nebula by more than 3 times. A strong correlation between the distance and the scattering strength is observed for pulsars behind the nebula. It is also observed that for distant pulsars ($> 2 kpc$), the effect of the Gum nebula in DM and scattering strength is not substantial. We also report a much flatter $\alpha$ for the Vela pulsar and argue that its scattering is not caused by the Gum nebula, but the Vela supernova remnant.