Astronomers using the Hubble Space Telescope and other observatories have discovered a pair of gravitationally-bound quasars inside two merging galaxies.
Quasars are active and luminous types of active galactic nuclei, and the European Space Agency explains that active galactic nuclei are extremely luminous galactic cores where gas and dust falling into a supermassive black hole emit electromagnetic radiation across the entire electromagnetic spectrum.
In a release, NASA explained that the bright quasars – powered by the black holes expelling fountains of energy – existed when the universe was just 3 billion years old.
"We don't see a lot of double quasars at this early time in the universe. And that's why this discovery is so exciting," lead study author and University of Illinois at Urbana-Champaign graduate student Yu-Ching Chen, said in a statement.
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The research was published Wednesday in the journal Nature.
The agency noted that there is increasing evidence that large galaxies are built up through merging smaller systems, with pairs of supermassive black holes within the galaxies.
New observatories have allowed scientists to identify times when two quasars are active at the same time and are close enough that they will eventually merge.
The search presented here required the combined efforts of the Hubble Telescope, Hawaii's W.M. Keck Observatories and the International Gemini Observatory, New Mexico's NSF Karl G. Jansky Very Large Array and NASA's Chandra X-ray Observatory.
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The ESA Gaia space observatory also helped to identify this double quasar in the first place.
Hublle's sharp resolution shows that this is a genuine pair of supermassive black holes including a tidal feature from the merging of two galaxies, where gravity distorts the shape of the galaxies forming two tails of stars. In addition, Gaia is able to detect subtle "jiggle" that mimics an apparent change in stellar position from some the quasars it observes.
The jiggle could be evidence of random fluctuations of light, according to the agency, as each member of the quasar pair varies in brightness and flashes like a railroad crossing signal – creating the illusion of jiggling.
The researchers also used the Keck telescope to make sure there is no lensing galaxy between Earth and the suspected double quasar, which no longer exists.
"Because Hubble peers into the distant past, this double quasar no longer exists. Over the intervening 10 billion years, their host galaxies have likely settled into a giant elliptical galaxy, like the ones seen in the local universe today," said NASA. "And, the quasars have merged to become a gargantuan, supermassive black hole at its center."
