# Investigating multi-frequency pulse profiles of PSRs B0329+54 and B1642-03 in an inverse Compton scattering (ICS) model

## TL;DR

This study analyzes multi-frequency pulse profiles of two pulsars using an inverse Compton scattering model, revealing how their emission geometries and radiation regions vary with frequency and differ due to their inclination and impact angles.

## Contribution

It demonstrates that the ICS model can effectively reproduce the radiation geometry of two pulsars and distinguishes their emission regions based on geometrical parameters.

## Key findings

- ICS model successfully reproduces pulsar radiation geometry
- Different emission regions for the two pulsars explained by geometrical angles
- Frequency evolution of beam angles modeled accurately

## Abstract

The emission geometries, e.g. the emission region height, the beam shape, and radius-to-frequency mapping, are important predictions of pulsar radiation model. The multi-band radio observations carry such valuable information. In this paper, we study two bright pulsars, (PSRs B0329+54 and B1642-03) and observe them in high frequency (2.5 GHz, 5 GHz, and 8 GHz). The newly acquired data together with historical archive provide an atlas of multi-frequency profiles spanning from 100 MHz to 10 GHz. We study the frequency evolution of pulse profiles and the radiation regions with the these data. We firstly fit the pulse profiles with Gaussian functions to determine the phase of each component, and then calculate the radiation altitudes of different emission components and the radiation regions. We find that the inverse Compton scattering (ICS) model can reproduce the radiation geometry of these two pulsars. But for PSR B0329+54 the radiation can be generated in either annular gap (AG) or core gap (CG), while the radiation of PSR B1642-03 can only be generated in the CG. This difference is caused by the inclination angle and the impact angle of these two pulsars. The relation of beaming angle (the angle between the radiation direction and the magnetic axis) and the radiation altitudes versus frequency is also presented by modelling the beam-frequency evolution in the ICS model. The multi-band pulse profiles of these two pulsars can be described well by the ICS model combined with the CG and AG.