What could be better than a quasar? That’s right, two quasars. Astronomers have spotted two rare double quasars for the first time, and the results show us the dynamic and messy consequences of galaxy formation.
Each galaxy is believed to host a supermassive black hole at its center. When galaxies merge, their black holes merge with them. At the height of the fusion process, huge volumes of gas and dust swirl towards the center of the galaxy. As all that gas and dust compresses in the black hole, it heats up.
The forces are so intense that the nuclei of these galaxies become “quasars”, blazing brighter than millions of normal galaxies put together and projecting massive jets of radiation thousands of light years into space.
Many of these quasars and many other normal galaxies have long been observed by astronomers. But double quasars? These would represent galaxies in a mid-fusion state, where gas and dust have compressed on the nucleus but the black holes themselves have not yet merged. Since this is such a brief phase in the evolution of fusion, astronomers had yet to observe one.
So far. Twice.
âWe estimate that in the distant universe, for 1,000 quasars, there is a double quasar. So finding these double quasars is like finding a needle in a haystack, âsaid lead researcher Yue Shen of the University of Illinois at Urbana-Champaign.
Astronomers developed a technique that looked for subtle flickers in the luminosity of quasars, a sign that the light we see may come from two competing nuclei rather than a single unified black hole. With both sets of doubles at hand, astronomers can begin to directly probe this extremely violent phase in the evolution of the galaxy.
âThis is truly the first sample of double quasars during the peak era of galaxy formation that we can use to probe ideas for how supermassive black holes come together to eventually form a binary,â said Nadia Zakamska, member of the Johns Hopkins University research team in Baltimore, Maryland.
âQuasars have a profound impact on the formation of galaxies in the universe,â Zakamska said. “Finding double quasars in this early age is important because we can now test our long-held ideas about how black holes and their host galaxies evolve together.”
With the new technique, we hope that astronomers can catch many more quasars in the act. Their Nature astronomy The article is a “proof of concept that really demonstrates that our targeted research for double quasars is very effective,” said Hsiang-Chih Hwang, team member, Johns Hopkins University graduate student and principal investigator of the program. Hubble. “This opens up a new direction where we can accumulate a lot more interesting systems to track, which astronomers weren’t able to do with previous techniques or datasets.”