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Using NuSTAR and XMM-Newton satellites, astronomers from New York University (NYU) Abu Dhabi have observed a pulsar known as PSR J1930+1852 and its pulsar wind nebula (PWN). Results of the observational campaign, in The Astrophysical Journal, yield more insights into the PWN and the pulsar that powers it.

Pulsar wind nebulae (PWNe) are structures powered by the wind of energetic pulsars. In general, a pulsar wind is composed of charged particles, and when it collides with the pulsar's surroundings—in particular with the slowly expanding supernova ejecta—it develops a nebula. Observations show that some PWNe may produce extended X-ray structures in the form of tails and prominent jets.

G54.1+0.3 is a PWN powered by the pulsar PSR J1930+1852, which has a large spin-down power, young characteristic age and a spin period of approximately 137 milliseconds. Previous observations have found that G54.1+0.3 is among the several PWNe that lack an obvious shell associated with a supernova remnant (SNR) forward shock.

A team of astronomers led by NYU Abu Dhabi's Jason Alford recently decided to take a closer look at PSR J1930+1852 and its associated PWN.

"In this paper, we present a comprehensive analysis of the broadband X-ray spectrum of the pulsar PSR J1930+1852 and its PWN G54.1+0.3 with these XMM-Newton and NuSTAR observations," the researchers wrote in the paper.

The observations detected X-ray emission from the combined pulsar and PWN system up to about 70 keV. The emission from G54.1+0.3 itself was detected at up to about 30 keV, with a photon index increasing from approximately 1.9 to 2.4 and with photon energy within the range of 3−30 keV.

By analyzing the X-ray spectrum of G54.1+0.3, the astronomers found that it is consistent with a broken power law, with break energy at a level of 5 keV. The maximum particle energy for this PWN was calculated to be 400 TeV.

Furthermore, the study found that G54.1+0.3 has a characteristic age of 2,830 years and its magnetic field was estimated to be some 7µG. The spin period of the pulsar PSR J1930+1852 was constrained to be approximately 137.2 milliseconds.

The astronomers compared the properties of G54.1+0.3 and PSR J1930+1852 to other pulsars with young PWNe (with characteristic ages of less than 5,000 years). They found that the investigated pulsar and its nebula showcase typical parameters among this group. However, G54.1+0.3 is not particularly powerful for its age.

Summing up the results, the astronomers noted that further studies of PSR J1930+1852 and its PWN are required in order to better constrain parameters such as the braking index, the spin down timescale, and the initial pulsar spin period.

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