Astronomers see a uncommon “double quasar” in a pair of merging galaxies

What’s better than a quasar? That’s right, two quasars. Astronomers have discovered two rare double quasars for the first time, and the results show us the dynamic, chaotic consequences of galaxy formation.

Every galaxy is believed to have a supermassive black hole at its center. When galaxies merge, their black holes merge with them. During the peak of the fusion process, huge amounts of gas and dust swirl into the center of the galaxy. As all of the gas and dust compress into the black hole, it heats up.

The forces are so strong that the cores of these galaxies become “quasars” that shine brighter than millions of normal galaxies together and that massive rays of radiation radiate into space for thousands of light years.

Astronomers have long observed many of these quasars and many more normal galaxies. But double quasars? These would represent galaxies in a state in the midst of fusion, in which gas and dust have been compressed onto the core, but the black holes themselves have not yet merged. Since this is such a brief phase in fusion development, astronomers had not observed any.

Until now. Twice.

“We estimate that in the distant universe there is one double quasar for every 1,000 quasars. So finding these double quasars is like finding a needle in a haystack, ”said senior researcher Yue Shen of the University of Illinois at Urbana-Champaign.

Astronomers developed a technique that looked for subtle flickers in the brightness of quasars, a sign that the light we see may have come from two competing nuclei rather than a single uniform black hole. With the two double sentences available, astronomers can begin to study directly this extremely violent phase of galaxy evolution.

“This is really the first sample of double quasars in the highest era of galaxy formation that we can use to study ideas of how supermassive black holes come together to eventually form a binary file,” said Nadia Zakamska, a member of the research team at Johns Hopkins University in Baltimore , Maryland.

“Quasars have a profound influence on the formation of galaxies in the universe,” said Zakamska. “Finding double quasars in this early epoch is important as we can now test our longstanding ideas of how black holes and their host galaxies evolve together.”

Hopefully, with the new technique, astronomers can catch many more quasars in the act. Her article on natural astronomy is a “proof of concept that really shows that our targeted search for double quasars is very efficient,” said team member Hsiang-Chih Hwang, a PhD student at Johns Hopkins University and principal researcher on the Hubble program. “It opens a new direction in which we can accumulate much more interesting systems for tracking that astronomers could not achieve with previous techniques or data sets.”

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