Investigation of gamma-ray variability and glitches of PSR J1420-6048

TL;DR

This study analyzes long-term gamma-ray data of PSR J1420-6048, revealing flux variability and four glitches, including two new ones, and explores potential causes such as background contamination and emission geometry changes.

Contribution

It provides the first detection of gamma-ray flux variability and four glitches in PSR J1420-6048, including two previously unknown glitches, and discusses their possible origins.

Findings

Detected four glitches, two of which are new.

Observed gamma-ray flux and spectral variability associated with glitches.

Discussed potential background contamination and emission geometry changes.

Abstract

PSR J1420-6048 is a young gamma-ray pulsar with recurrent glitches. Utilizing long-term monitoring data obtained from the Fermi Gamma-ray Space Telescope, we found that PSR J1420-6048 has shown gamma-ray flux variation and we also detected four glitches between 2008 and 2019. Two of the glitches are previously unknown, and their gamma-ray spectrum also shows variability between each glitch. Since the results might be contaminated by background sources, we discuss whether the observed changes in flux and spectra were caused by artificial misallocations of photons from a nearby pulsar wind nebula (HESS J1420-607) and a pulsar (PSR J1418-6058), or a change of the emission geometry from the target pulsar itself. We examine the correlation of the flux changes and the alternating pulse structure to investigate whether the emission geometry in the outer magnetosphere was changing. By assuming the observational features were not totally resulted from the background environment, we compare our results with similar phenomena observed in other gamma-ray pulsars and propose that a strong crust crack can cause timing anomaly of a neutron star, which can affect the particle accelerations or pair creation regions resulting in the changes of emission behaviors.