Astronomers said on April 6, 2021, that they had spotted two rare double quasars. It is believed that each pair lives in the middle of two merging galaxies in the very distant universe. Astronomers estimate that only one in every 1000 quasars is double, so it may be lucky to find two double quasars. However, the astronomers would tell you that they did not use luck. They used a series of telescopes that led them from one step to the next, in a methodical unraveling of the mystery of which clear, apparently single quasars could actually be double. As principal researcher Yue Shen of the University of Illinois at Urbana-Champaign put it:
Finding these double quasars is like finding a needle in a haystack.
A collaboration between scientists and some of the best telescopes in the world has led to new images of the double quasars. The study was published in the peer-reviewed journal on April 1, 2021 Natural Astronomy.
To find the quasar pairs, astronomers searched 3D maps of the Sloan Digital Sky Survey to find candidates for double quasars. Then they used data from the Gaia Observatory to determine the locations. Gaia is able to detect light gills in the movement of the distant quasars. Because quasars vary in brightness depending on how much material the black hole consumes at the time, it has a slightly flickering appearance. The scientists compare the alternating brightness between the quasar pair, as seen in the video above, with that of the double flashing lights at a railway crossing. Finally, the team of scientists used the Hubble Space Telescope to propose four candidates, two of whom appear to be nearby quasars.
The video simulation above shows the brilliant, flickering light from some quasars. Astronomers have concluded that the flashing light is a sign of the presence of two quasars and not a single object.
Each of the two newly discovered pairs of quasars – or four total quasars – was discovered within 10,000 light-years of their mate. It is very close on a cosmic distance scale; by comparison, our sun is about 26,000 light-years from the supermassive black hole in the center of our Milky Way galaxy.
A quasar is an object in the distant universe that produces amazing amounts of energy. Quasars have such an astonishing sparkle that they can be seen over the wide corners of the universe. So we see them at a time when the universe was young, and so they can help reveal conditions in the early cosmos. Quasars presumably lie at the heart of young galaxies in the early universe. It is suspected that the energy of a quasar is created when a supermassive black hole furiously feeds on the apostate matter. The light of these two quasar pairs comes to us from the time when the universe was about 10 billion years old. If we could see them today, as they are now, we can see that each quasar pair joined together to form a new giant black hole.
More than 100 double quasars are already known, but no one is as far into space and as far back in time as these new pairs. Scientists hope the discoveries will provide a new way to investigate collisions between galaxies and the fusion of supermassive black holes in the early universe. Team member Nadia Zakamska of Johns Hopkins University said:
This is truly the first example of double quasars during the peak period of galaxy formation that allow us to explore ideas about how supermassive black holes come together to eventually form a binary.
As these stellar galaxies begin to merge and send the gas of gravity-deforming material inward, the quasars shoot up. The radiation coming from the quasar will eventually drive winds that rub the interior of the galaxy free of gas and dust. This creates a shortage of star-forming material, and as star formation ceases, the galaxies descend into their elliptical shapes.
Zamaska explained the importance of this discovery:
Quasars have a major influence on the formation of galaxies in the universe. Finding double quasars in this early period is important because we can now test our long-standing ideas about how black holes and their host systems can develop together.
Look bigger. | On the left is the quasar pair J0749 + 2255, which was imaged by the Hubble Space Telescope on January 5, 2020. On the right is the quasar pair J0841 + 4825, pictured on November 30, 2019 by Hubble. The galaxies in which they reside can be seen with any current telescope. Image via NASA / ESA.
This artist’s concept shows two shiny bright quasars and the merging galaxies in which they live. Both quasars have supermassive black holes at their core. A new study suggests that as the two galaxies merge and the quasars get closer together, the two black holes will merge into an even more massive black hole. Image via NASA / ESA / J. Olmsted / STSci.
One day, a double quasar and galactic fusion, as scientists have seen far across the universe, will happen much closer to home. Our Milky Way galaxy and the adjacent Andromeda galaxy are in a collision. In a few billion years from now, if our two galaxies start interacting and matter pulls apart, the currently quiet, supermassive black holes in the center of the galaxies will catch fire. The precipitating material will illuminate the quasars and create two brilliant spotlights that will shine as brightly or brighter as a full moon in our night sky. The radiance of the quasars will sterilize planets and exterminate civilizations within reach.
In short: scientists recently released Hubble images of the farthest and oldest known pairs of quasars in merging galaxies.
Source: a hidden population of high-red-shift double quasars introduced by astrometry
Via Hubblesite
