# Probing pulsar scattering between 120 and 280 MHz with the MWA

## TL;DR

This study uses the Murchison Widefield Array to measure pulsar scattering spectral indices across 120-280 MHz, revealing different scattering behaviors and models for three bright pulsars, with implications for understanding interstellar turbulence.

## Contribution

It provides new measurements of scattering spectral indices for three pulsars at low frequencies, highlighting the role of the thin screen model and turbulence inner scale effects.

## Key findings

- Vela and J0742-2822 fit a thin screen scattering model with Gum Nebula contribution.
- Crab pulsar shows unique pulse shapes not explained by existing models.
- Finite turbulence inner scale may account for discrepancies in scattering profiles.

## Abstract

The high sensitivity and wide frequency coverage of the Murchison Widefield Array allow for the measurement of the spectral scaling of the pulsar scattering timescale, $\alpha$, from a single observation. Here we present three case studies targeted at bright, strongly scattered pulsars J0534+2200 (the Crab pulsar), J0835-4510 (the Vela pulsar) and J0742-2822. We measure the scattering spectral indices to be $-3.8\pm0.2$, $-4.0\pm1.5$, and $-2.5\pm0.6$ for the Crab, Vela, and J0742-2822, respectively. We find that the scattered profiles of both Vela and J0742-2822 are best described by a thin screen model where the Gum Nebula likely contributes most of the observed scattering delay. For the Crab pulsar we see characteristically different pulse shapes compared to higher frequencies, for which none of the scattering screen models we explore are found to be optimal. The presence of a finite inner scale to the turbulence can possibly explain some of the discrepancies.