Wideband Monitoring Observations of PSR J1803-3002A in the Globular Cluster NGC 6522

TL;DR

This paper presents the first wideband radio observations of the isolated millisecond pulsar PSR J1803-3002A in NGC 6522, revealing detailed emission properties and polarization behavior across a broad frequency range.

Contribution

It provides new insights into the emission and polarization characteristics of PSR J1803-3002A using ultra-wideband observations, demonstrating the capabilities of the UWL receiver system.

Findings

Pulse profile has three components with frequency-dependent prominence.

Mean spectral index of -1.66 for pulsed emission.

Unusual increase in polarization with frequency.

Abstract

We report the first wideband monitoring observations of PSR J1803-3002A, a relatively bright millisecond pulsar in the globular cluster NGC 6522 with a spin period of 7.1 ms and no known binary companion. These observations were performed using the Parkes 64-m radio telescope with the Ultra-Wideband Low (UWL) receiver system, which covers 704 to 4032 MHz. We confirm that PSR J1803-3002A is an isolated millisecond pulsar located near the cluster center and probe the emission properties of the pulsar over the wide observed band. The mean pulse profile consists of three components, with the outer components becoming more prominent at higher frequencies, and a mean spectral index for the pulsed emission of -1.66+/-0.07 over the observed band. The fractional linear and circular polarization increase with increasing frequency, which is unusual for pulsars. We determine a Faraday rotation measure of -107+/-6 rad m-2 for the pulsar. PSR J1803-3002A is a distant pulsar in the Galactic plane, but there is no evidence of pulse broadening due to interstellar scattering in our observations. These results demonstrate the power of ultra-wideband receiving and signal processing systems.