European Space Agency

ESA’s XMM-Newton has found a new pulsar

A pulsar has been spotted by ESA’s XMM-Newton. According to the latest data the spinning remains of a once-massive star which turned out to be a thousand times brighter than previously thought possible. What is more, the spotted pulsar is also the most distant of its kind ever detected. Its light travelled 50 million light-years before being detected by XMM-Newton.

By their nature, pulsars were once massive stars that exploded as a powerful supernova at the end of their natural life, before becoming small and extraordinarily dense stellar corpses.

The object has been observed several times within last 13 years and is 10 times brighter than the previous record holder. In one second it emits the same amount of energy released by our Sun in 3.5 years.

The signal was also identified in NASA’s Nustar archive data, providing additional information.

“Before, it was believed that only black holes at least 10 times more massive than our Sun feeding off their stellar companions could achieve such extraordinary luminosities, but the rapid and regular pulsations of this source are the fingerprints of neutron stars and clearly distinguish them from black holes,” says Gian Luca Israel, from INAF-Osservatorio Astronomica di Roma, Italy, lead author of the paper describing the result published in Science this week.

It also turned out that from 2003 to 2014 the pulsar’s spin rate has changed from 1.43 s per rotation to 1.13. If the same acceleration occurred in Earth’s rotation, our day would be five hours shorter in the same time span.

“Only a neutron star is compact enough to keep itself together while rotating so fast,” adds Gian Luca.

Although the rotation rate of a neutron star tend to change as the time passes, the high rate of change in this case is likely linked to the object rapidly consuming mass from a companion.

“This object is really challenging our current understanding of the ‘accretion’ process for high-luminosity stars,” says Gian Luca. “It is 1000 times more luminous than the maximum thought possible for an accreting neutron star, so something else is needed in our models in order to account for the enormous amount of energy released by the object.”

“The discovery of this very unusual object, by far the most extreme ever discovered in terms of distance, luminosity and rate of increase of its rotation frequency, sets a new record for XMM-Newton, and is changing our ideas of how such objects really ‘work’,” says Norbert Schartel, ESA’s XMM-Newton project scientist.

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