Toward an Empirical Theory of Pulsar Emission XII: Exploring the Physical Conditions in Millisecond Pulsar Emission Regions

TL;DR

This paper investigates the emission regions of millisecond pulsars, finding they likely emit via curvature radiation from charged solitons, similar to slow pulsars, despite their smaller magnetospheres.

Contribution

It provides the first detailed estimates of emission heights and physical conditions in MSPs, demonstrating their emission mechanisms are akin to those of slow pulsars.

Findings

MSPs exhibit core/double-cone and core/single-cone emission profiles.

Emission heights in MSPs are estimated to be significantly lower than in slow pulsars.

MSPs likely emit radio waves through curvature radiation from charged solitons.

Abstract

The five-component profile of the 2.7-ms pulsar J0337+1715 appears to exhibit the best example to date of a core/double-cone emission-beam structure in a millisecond pulsar (MSP). Moreover, three other MSPs, the Binary Pulsar B1913+16, B1953+29 and J1022+1001, seem to exhibit core/single-cone profiles. These configurations are remarkable and important because it has not been clear whether MSPs and slow pulsars exhibit similar emission-beam configurations, given that they have considerably smaller magnetospheric sizes and magnetic field strengths. MSPs thus provide an extreme context for studying pulsar radio emission. Particle currents along the magnetic polar flux tube connect processes just above the polar cap through the radio-emission region to the light-cylinder and the external environment. In slow pulsars radio-emission heights are typically about 500 km around where the magnetic field is nearly dipolar, and estimates of the physical conditions there point to radiation below the plasma frequency and emission from charged solitons by the curvature process. We are able to estimate emission heights for the four MSPs and carry out a similar estimation of physical conditions in their much lower emission regions. We find strong evidence that MSPs also radiate by curvature emission from charged solitons.