The Shapes of Pulsar Radio Pulses in the Plane of the Sky

TL;DR

This paper models the sizes and shapes of pulsar radio pulses in the sky plane, considering different emission modes and geometries, to aid in resolving pulsar emission regions and testing emission theories.

Contribution

It provides the first detailed modeling of pulsar radio pulse images in the sky plane for various geometries and emission parameters, including mode-specific shapes and size variations.

Findings

Pulse image size is smaller at the pulse center than at the edges.

The shape and size of the pulse images depend on the emission mode and geometrical parameters.

Models can help constrain pulsar emission theories and guide observational resolution efforts.

Abstract

The sizes of pulsar radio pulses in the plane of the sky are determined. This is important not only in relation to the possibility of directly resolving the radio pulses spatially, but also for verifying and placing constraints on existing theories of the radio emission. The shape of the pulse radio image and its variation as a function of the pulse phase for the extraordinary (X) and ordinary (O) modes are determined for the simple case of a dipolar magnetic field. Images are obtained for pulsars with various angles between their magnetic and rotational axes, and also for various model parameters, such as the height of the emission, the size of the emission region as a function of the height, and the Lorentz factor of the secondary plasma. It is shown that the size of the resulting image is appreciably smaller at the center of the pulse than at its edges.