Astronomers have detected a flickering quasar, J0439+1634, as it appeared only 850 million years after the Big Bang, challenging existing models of black hole formation. The object's variability suggests its central black hole hosts a flat, pancake-shaped accretion disk. That structure closely resembles those seen in modern-day quasars, raising new questions about how such objects could form so rapidly in the early Universe.
The discovery hinges on the flickering light of the quasar, which acts like a cosmic lighthouse signaling the behavior of matter as it spirals into the black hole. The rapid brightness changes imply a compact accretion disk, more typical of mature quasars than those expected at cosmic dawn. This shape offers clues about the physical processes governing black hole feeding mechanisms in the infant cosmos.
J0439+1634 was observed at a redshift corresponding to just 850 million years after the Big Bang, placing it firmly in the epoch of reionization. The quasar's rapid flickering timescale was measured over just a few hours of observational data, indicating the emitting region is relatively small. Previous surveys had cataloged this object, but the new variability detection required dedicated monitoring.
The finding carries profound implications for understanding supermassive black hole growth. Standard models struggle to explain how billion-solar-mass black holes could form in less than a billion years. The presence of a standard accretion disk so early suggests either unusually efficient accretion or an initially massive seed black hole.
A key counterargument is that the observed flickering might instead arise from gravitational microlensing by foreground stars, which could mimic intrinsic disk variability without requiring exotic early-Universe physics. Longer baseline observations are needed to confirm whether the signal is truly intrinsic to the quasar's accretion flow.