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Chinese astronomers have used NASA's Fermi gamma-ray space telescope to conduct a long-term study of a bright gamma-ray pulsar known as PSR J0007+7303. In their results, they identified more glitching events in this pulsar. The new findings were July 24 on the arXiv preprint server.

Pulsars are highly magnetized rotating neutron stars that emit beams of electromagnetic radiation at regular intervals typically ranging from milliseconds to seconds. Observations show that many pulsars exhibit sudden step-like increases of rotation frequency, known as glitches.

Located some 4,500 light years away, PSR J0007+7303 is a bright radio-quiet gamma-ray pulsar in the supernova remnant CTA1. It has a spin period of approximately 0.316 seconds and a characteristic age of about 13,900 years.

PSR J0007+7303 was the first pulsar detected by Fermi and previous observations of this pulsar using the Large Area Telescope (LAT) onboard Fermi have detected its four glitches. Now a team of astronomers, led by Zhi-Xiang Yu of the Guizhou Normal University in China, reports more glitching behavior in PSR J0007+7303.

"In this paper, we present the 15 years of timing results of this pulsar using the Fermi-LAT data. We identified nine glitches, five of which are newly discovered," the researchers wrote.

The newly detected glitches have magnitudes ranging from 10^-6 to 10^-9, and two of them were classified as small glitches occurring between the previously reported ones. The observations show that there is no significant exponential recovery following any of the known nine glitches of PSR J0007+7303.

According to the paper, the glitches occur at intervals of approximately 1–2 years and the glitch rate was calculated to be approximately 0.56 per year, which is consistent with the young age of the star. The astronomers noted that the waiting time of glitches on the pulsar is random, as the longest interval exceeds three years and the shortest is 44 days.

Furthermore, Yu's team analyzed the effect of glitches on the evolution of the flux, pulse profiles and average phase spectral. However, no significant changes were detected, which indicates the stability of the pulsar's emission properties despite internal changes.

The astronomers also conducted a parametric analysis of the glitches. The results indicate a fractional moment of inertia of the crustal superfluid involved in glitches as approximately 1.06%. This, according to the astronomers, suggests the internal origin of the glitches in PSR J0007+7303.

The authors of the paper now plan to perform further pulsar timing monitoring of PSR J0007+7303, in order to identify more glitch events. This would help them to better understand the physical mechanisms behind the glitching phenomenon in pulsars.

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