Is the ultradense core of a gigantic star lurking in the center of the Milky Way?

Scientists think they may have found just that: the signal of a pulsar, a rapidly rotating ancient star core, in the heart of our galaxy. The rare discovery could be used to test the predictions of Einstein's general relativity.

Pulsars, a kind of neutron star, are known as "cosmic lighthouses" because they send out beams of radio emissions with every spin, and these beams occasionally strobe past Earth. The suspected pulsar whips around on its axis every 8.19 milliseconds and is located near Sagittarius A*, a supermassive black hole with the mass of 4 million suns embedded in the Milky Way's center.

The researchers published their findings Monday (Feb. 9) in The Astrophysical Journal. The work was led by Karen Perez, a postdoctoral researcher at the SETI Institute who was a doctoral student at Columbia University at the time of the research.

"We're looking forward to what follow-up observations might reveal about this pulsar candidate," Perez said in a statement. In particular, she added, the researchers hope to use the pulsar to probe general relativity.

Testing the rules of the universe

General relativity, first proposed by Albert Einstein, proposes that gravity is not a force in nature but a property of how space-time curves.

A nearby pulsar in the Milky Way would let researchers learn about "precision measurements of the space-time around a supermassive black hole," the statement noted. That's because pulsars rotate so rapidly that they are sensitive to the subtle gravitational pulls of massive neighboring objects, like other stars.

The pulsar's rotation could then, in theory, produce "anomalies" in the pulses of light that it sends toward Earth, said study co-author Slavko Bogdanov, a research scientist at the Columbia Astrophysics Laboratory.

"In addition, when the pulses travel near a very massive object, they may be deflected and experience time delays due to the warping of space-time, as predicted by Einstein's general theory of relativity," Bogdanov added.

Researchers detected the suspected pulsar through Breakthrough Listen, a scientific research program that aims to find signals of civilizations beyond Earth. The new findings came from the Breakthrough Listen Galactic Center Survey, which, as the name suggests, hunted for signals coming from the center of the Milky Way.

Breakthrough Listen released all of the data publicly, the researchers added, "allowing researchers worldwide to pursue independent analyses and complementary science cases."

Further research is needed to confirm whether the signal really was a pulsar, or if it came from some other exotic radio source.

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