Astronomers have detected the flickering of a quasar that existed only 700 million years after the Big Bang. Its light has traveled to us for more than 13 billion years. Over several years of observations, its brightness fluctuated noticeably, helping scientists understand how the earliest supermassive black holes behaved in the young Universe.
Flares in the Early Universe
The quasar is designated J0008+0212. Its redshift reaches 6.9, which means we see it as it was roughly 700 million years after the Big Bang. Objects like this belong to the era of cosmic dawn, when the first stars and galaxies had only just begun to disperse the primordial darkness.
The light curve of J0008+0212 was reconstructed using data from several sky surveys, including the Dark Energy Survey and the WISE space telescope. It turned out that over several years, the quasar’s brightness varied by about 0.5 magnitude. For such an ancient object, this is the first recorded case of such rapid flickering. Previously, similar behavior had been observed only in much closer quasars.
Accretion on the Edge of Stability
The most convincing explanation for these brightness fluctuations is linked to the behavior of the accretion disk around the supermassive black hole that powers the quasar. The disk appears to be unstable, causing matter to fall onto the black hole unevenly and producing bursts of radiation.
The study was published in the peer-reviewed journal The Astrophysical Journal. Its authors, led by Siwei Zhang of the University of Arizona, analyzed not only optical but also infrared data, which made it possible to separate the contribution of the accretion disk from the radiation of the dusty torus surrounding it. This approach allowed them to state with confidence that the flickering was caused by processes in the accretion disk itself, rather than by external factors.
Why This Changes the Picture
The discovery of unstable accretion in a quasar from the era of cosmic dawn forces scientists to rethink how quickly the first supermassive black holes grew. Previously, accretion in the early Universe was thought to be relatively calm and predictable. Now it appears that it may have been turbulent and intermittent.
This is important for estimating the overall mass-growth rate of the first black holes, because an unstable disk means that matter is not absorbed as efficiently as models had predicted. As a result, the growth rates of supermassive black holes in the young Universe may have been slower, while the mechanisms behind their formation may be even more mysterious than previously thought.
Further Observations of the Quasar
The results so far concern only a single object, so it is too early to draw definitive conclusions. J0008+0212 will continue to be monitored using both ground-based and space-based instruments in order to track its behavior over a longer period of time.
Astronomers will also search for other quasars with similar properties at the same cosmic distances. If flickering turns out to be common among the earliest quasars, it would mean that unstable accretion was more likely the rule than the exception in the early Universe.
According to universetoday.com
