An unified polar cap/striped wind model for pulsed radio and gamma-ray emission in pulsars

TL;DR

This paper presents a unified model combining polar cap and striped wind geometries to explain the radio and gamma-ray emission in pulsars, analyzing phase lags and peak separations to match observations from Fermi data.

Contribution

It introduces a combined polar cap and striped wind model to explain pulsar emission properties and compares predictions with Fermi observations.

Findings

The model reproduces observed phase lags between radio and gamma-ray pulses.

Gamma-ray peak separation depends on pulsar inclination and viewing angles.

Predicted radio lag and peak separation relations align with Fermi data observations.

Abstract

(abridged) Thanks to the recent discovery by Fermi of about fifty new gamma-ray pulsars, it becomes possible to look for statistical properties of their pulsed high-energy emission, especially their light-curves and phase-resolved spectra. These pulsars emit by definition mostly gamma-ray photons but some of them are also detected in the radio band. For those seen in these two extreme energies, the relation between time lag of radio/gamma-ray pulses and gamma-ray peak separation, in case both high-energy pulses are seen, helps to put some constrain on the magnetospheric emission mechanisms and location. This idea is analyzed in detail in this paper, assuming a polar cap model for the radio pulses and the striped wind geometry for the pulsed high-energy counterpart. Combining the time-dependent emissivity in the wind, supposed to be inverse Compton radiation, with a simple polar cap emission model along and around the magnetic axis, we compute the radio and gamma-ray light-curves, summarizing the results in several phase plots. The phase lag as well as the gamma-ray peak separation dependence on the pulsar inclination angle and on the viewing angle are studied. Using the gamma-ray pulsar catalog compiled from the Fermi data, we are able to predict the radio lag/peak separation relation and compare it with available observations taken from this catalog.