Scientists direct evidence of a pulsing quasar that could prove the existence of the merge of two black holes into close-orbiting binaries.

Researchers believe as two galaxies enter the final stages of merging, the supermassive black holes form a binary, but this has never been proven, the University of Maryland reported. In this phenomenon the black holes would be in such close orbit that they would be gravitationally bound to one another.

"We believe we have observed two supermassive black holes in closer proximity than ever before," said Suvi Gezari, assistant professor of astronomy at the University of Maryland and a co-author of the study. "This pair of black holes may be so close together that they are emitting gravitational waves, which were predicted by Einstein's theory of general relativity."

Black holes usually take in matter, causing it to accelerate and emit electromagnetic energy, which can be viewed as a brilliant quasar. When two black holes orbit as a binary they absorb matter cyclically, suggesting they would periodically brighten and dim.

The researchers used the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) Medium Deep Survey to search the sky for these types of quasars. The study led to the discovery of quasar PSO J334.2028+01.4075, which contains a black hole of 10 billion solar masses that emits a periodic optical signal that repeats every 542 days.

"The discovery of a compact binary candidate supermassive black hole system like PSO J334.2028+01.4075, which appears to be at such close orbital separation, adds to our limited knowledge of the end stages of the merger between supermassive black holes," said UMD astronomy graduate student Tingting Liu, the paper's first author.

The findings were published in a recent edition of the Astrophysical Journal Letters.