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Bright quasar lit up the early universe

Astronomers have spotted the brightest quasar (shown here in artist’s impression) discovered in the early universe.
(ESA/Hubble, NASA, M. Kornmesser)

Astronomers have discovered a galaxy is a supermassive black hole at its core, and it is located 12.8 billion light-years away from the Earth, only a billion years before the Big Bang. Known as a quasar, this object is the brightest of its kind ever seen in the distant universe. The discovery gives scientists a better look at the universe in its first years and helps them to understand how supermassive black holes form and evolve.

The new quasar, called UHS J043947.08+163415.7, was discovered by the use of gravitational lensing, a phenomenon in which a distant object’s light is magnified by the gravity of a closer object. The intermediate, or lensing, galaxy in this case, the quasar will appear 50 times brighter than would otherwise be the case. [Big Bang to Civilization: 10 Amazing Origin Events]

“The reason that this one was discovered — a little bit of luck, actually — because the quasar is so bright and the lensing galaxy is very weak in comparison with all other lensing galaxies that we know of,” lead author and astronomer Xiaohui Fan of the University of Arizona, told Science. “That object had been sitting in the database for a few years now, but no one had looked to that part of the sky for quasars, because we usually don’t.”

The quasar was found in the constellation Taurus, which is close to the plane of the Milky way galaxy. The astronomers, in general, to avoid looking for quasars in this region, because of the abundance of stars and dust drown out the weak quasar light.

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The quasar was first mapped in multiple colors by two all-sky survey, the UKIRT Hemisphere Survey, and Pan-STARRS1. Astronomers typically use computer algorithms to compare colors to identify high redshift objects, the meaning of which the light from these objects is shifted towards the red wavelengths of the spectrum as a result of the move away from us. If the lensing galaxy in this system, it was only a half-magnitude brighter, the researchers have completely missed the quasar. Fan said that this kind of strict color-selection criteria has probably caused other quasars to be overlooked.

“At such large distances, [quasars] are also very rare,” said Laura Pentericci, an astronomer who studies distant galaxies, INAF Rome Astronomical Observatory, but that was not part of the new study. For example, despite the search for more than a decade, astronomers have found only two quasars are more than 13 billion light-years away, Pentericci told Live Science. Fortunately, the new studied quasar and the galaxy were just bright enough to be designated as a potential far-universe objects. The astronomers are following analyzed data showing the individual wavelengths emitted by the quasar. By analyzing these specific wavelengths of light, in particular a broadcast by magnesium, the astronomers were able to confirm that the quasar distance.

The spectroscopic data also allowed the researchers to estimate the mass of the quasar’s central supermassive black hole; they calculated at around 700 million times that of the sun. That is more than 150 times larger than the black hole at the center of the Milky way. While the mass of the new quasar’s black hole means that it is large for the early universe, it is not the biggest, Fan told Live Science. “Of course, we can only large objects from that time, so almost everything we see from that time is quite large.”

Studies of early quasars give the scientists insight into our universe’s youth. Quasars are powered by black holes, so they can tell us when and how the first black holes formed. Quasars’ intense light also acts as a beacon shining through the intergalactic space. As a quasar’s light travels to the Earth, that the light passes through the intergalactic gas, which absorbs specific wavelengths of light depending on the gas temperature and composition. Astronomers can then decode the quasars’ light to learn about the material between the galaxies that is much too weak to directly see.

The researchers in the new study are already to learn more about this new quasar. They also plan to re-analyze older data to see if they missed other quasars.

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Originally published on Live Science.

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