There’s a lot that we don’t know about the early universe and all the new discoveries seem to suggest that even things we have a good grasp of are still hiding surprises. One of these is related to how quickly supermassive black holes (SMBH) formed.
Three quasars have been observed with some seriously supermassive black holes, with a mass the size of a billion Suns. Strangely, they have only been growing for less than a 100,000 years, which is thousands of times faster than people expect their growth rate to be.
“This is a surprising result,” lead author Christina Eilers, a doctoral student at Max Planck Institute for Astronomy, said in a statement. “We don’t understand how these young quasars could have grown the supermassive black holes that power them in such a short time.”
The study, published in the Astrophysical Journal, focuses on the proximity zones of quasars. These are regions surrounding the primordial active galaxies where the intense radiation from the supermassive black holes have ionized (made transparent) the intergalactic gas. Out of the 34 quasars studied, three had a very small proximity zone and the most likely scenario modeled suggests that these SMBHs formed extremely quickly.
The light of these quasars took 13 billion years to travel to us and what we are seeing is how these objects looked just a few hundred million years after the Big Bang.
Astronomers assume a bottom-up formation mechanism, where small structures formed first and then merged into bigger and bigger objects. Under that assumption, large black holes formed from the supernovae of the first massive stars. These black holes then merge with each other until they became supermassive. But the SMBHs powering these quasars are challenging everything we know about how long it takes to get this big.
“No current theoretical models can explain the existence of these objects,” explained co-author and team leader Professor Joseph Hennawi. “The discovery of these young objects challenges the existing theories of black hole formation and will require new models to better understand how black holes and galaxies formed.”
To solve this conundrum the team is already planning new observations hunting more quasars similar to the three they found.
“We would like to find more of these young quasars,” admitted Eilers. “While finding these three unusual quasars might have been a fluke, finding additional examples would imply that a significant fraction of the known quasar population is much younger than expected.”
Understanding these objects, especially if they are not flukes, might tell us a lot more about how objects grew during the earliest time of the universe.
1
