IXPE Polarizations of the Lighthouse Pulsar, Trail, and Filament

TL;DR

This study reports the first X-ray polarization measurements of the Lighthouse pulsar, its trail, and filament, revealing magnetic field structures and turbulence levels that challenge existing models.

Contribution

First IXPE polarization observations of the Lighthouse pulsar complex, providing new insights into magnetic field orientation and turbulence in the filament and trail.

Findings

Filament polarization degree is 55% with magnetic field parallel to its axis.

Trail's X-ray polarization is nearly orthogonal to radio polarization.

Pulsar polarization fits the rotating vector model.

Abstract

The Lighthouse pulsar (PSR J1101$-$6101) sports a bright X-ray trail and filament. The synchrotron emission from both structures is expected to be polarized, with electric vector position angle (EVPA) perpendicular to the magnetic field direction and polarization degree (PD) indicating the local degree of magnetic turbulence. We present a 1 megasecond Imaging X-ray Polarimetry Explorer (IXPE) observation of the Lighthouse complex. At the 99% confidence level, we detect the filament polarization with PD $55 \pm 18\%$ and EVPA indicating a magnetic field parallel to the filament axis. The large PD implies a turbulent magnetic field weaker than the background field, in conflict with some existing models. We also detect polarization from the pulsar and trail. The trail's X-ray polarization is nearly orthogonal to the radio polarization, suggesting spatial separation between the X-ray- and radio-emitting leptons. The pulsar polarization is well-fit by the rotating vector model.