Published: 13th January 2019
Scientists identify ancient quasar provides glimpse into early history of the universe
Before the cosmos reached its billionth birthday, some of the very first cosmic light began a long journey through the expanding universe
Scientists have identified an extremely distant quasar that may provide a glimpse into the early history of the universe. A quasar is a massive and extremely remote celestial object, emitting exceptionally large amounts of energy, and typically having a starlike image in a telescope.
Astronomers, using observations from Gemini Observatory, detected the light emitted from the dawn of time thanks to a foreground galaxy acting as a gravitational lens, which magnified the quasar's ancient light. The Gemini observations provide critical pieces of the puzzle in confirming this object as the brightest appearing quasar so early in the history of the universe, raising hopes that more sources like this will be found.
Before the cosmos reached its billionth birthday, some of the very first cosmic light began a long journey through the expanding universe.
One particular beam of light, from an energetic source called a quasar, passed near an intervening galaxy, whose gravity bent and magnified the quasar's light and refocused it in our direction, allowing telescopes like Gemini North to probe the quasar in great detail.
"If it weren't for this makeshift cosmic telescope, the quasar's light would appear about 50 times dimmer," said Xiaohui Fan of the University of Arizona who led the study.
"This discovery demonstrates that strongly gravitationally lensed quasars do exist despite the fact that we've been looking for over 20 years and not found any others this far back in time," said Fan. The Gemini observations also led to a determination of the mass of the black hole powering the quasar.
"When we combined the Gemini data with observations from multiple observatories on Maunakea, the Hubble Space Telescope, and other observatories around the world, we were able to paint a complete picture of the quasar and the intervening galaxy," said Feige Wang of the University of California, Santa Barbara, who is a member of the discovery team.
Researchers found that the quasar is located extremely far back in time and space -- shortly after what is known as the Epoch of Reionization -- when the very first light emerged from the Big Bang. "This is one of the first sources to shine as the Universe emerged from the cosmic dark ages," said Jinyi Yang of the University of Arizona.
"Prior to this, no stars, quasars, or galaxies had been formed, until objects like this appeared like candles in the dark," said Yang. The foreground galaxy that enhances our view of the quasar is especially dim, which is extremely fortuitous.
"If this galaxy were much brighter, we wouldn't have been able to differentiate it from the quasar," said Fan, adding that this finding will change the way astronomers look for lensed quasars in the future and could significantly increase the number of lensed quasar discoveries.
The intense brilliance of the quasar, known as J0439+1634, also suggests that it is fueled by a supermassive black hole at the heart of a young forming galaxy. The broad appearance of the magnesium fingerprint captured by Gemini also allowed astronomers to measure the mass of the quasar's supermassive black hole at 700 million times that of the Sun.
The supermassive black hole is most likely surrounded by a sizable flattened disk of dust and gas. This torus of matter -- known as an accretion disk -- most likely continually spirals inward to feed the black hole powerhouse.