A 6.5-GHz Multibeam Pulsar Survey

TL;DR

This paper reports a high-frequency pulsar survey at 6.5 GHz using the Parkes telescope, discovering three new pulsars, detecting known pulsars, and providing insights into pulsar populations near the Galactic center, emphasizing the importance of high-frequency observations.

Contribution

It presents the first high-frequency survey of the Galactic plane at 6.5 GHz, discovering new pulsars and analyzing the effectiveness of high-frequency surveys for Galactic center pulsar detection.

Findings

Discovered 3 new pulsars with high dispersion measures

Detected the radio magnetar PSR J1550-5418 prior to previous observations

High-frequency surveys are crucial for discovering pulsars near the Galactic center

Abstract

A survey of the Galactic plane in the region $-60\degree \leq l \leq 30\degree$, $|b| \leq 0.25\degree$ was carried out using the seven-beam Parkes Methanol Multibeam (MMB) receiver, which operates at a frequency of 6.5 GHz. Three pulsars were discovered, and 16 previously known pulsars detected. In this paper we present two previously-unpublished discoveries, both with extremely high dispersion measures, one of which is very close, in angular distance, to the Galactic centre. The survey data also contain the first known detection, at radio frequencies, of the radio magnetar PSR J1550-5418. Our survey observation was made 46 days prior to that previously published and places constraints on the beginning of pulsed radio emission from the source. The detection of only three previously undiscovered pulsars argues that there are few pulsars in the direction of the inner Galaxy whose flux density spectrum is governed by a flat power law. However, these pulsars would be likely to remain undetected at lower frequencies due to the large amount of scatter broadening which affects pulsars with high values of dispersion measure. Surveys with future telescopes at high observing frequencies will, therefore, play an important role in the discovery of pulsars at the Galactic centre. By simulating pulsar surveys of the Galaxy with Phase 1 SKA at frequencies of 1.4 GHz and 10 GHz, we find that high-frequency observations are the only way to discover and observe the Galactic-centre pulsar population.