Most astronomers agree that at the center of every galaxy lies a supermassive black hole. But how did these gravitational monsters form? Now it seems that they may have been here since the beginning of time.
At least, they've been here as long as the galaxies they inhabit, which places them very near the origin of time and space as we know it.
Astrophysicst Ezequiel Treister and colleagues pored over hundreds of images from Chandra X-Ray Observatory, carefully tracking tiny amounts of x-ray photons originating from extremely distant (and therefore ancient) black holes at the cores of galaxies. What they discovered was that the origins of these black holes had been largely obscured by billowing clouds of gas around them as galaxies formed. But keener observation revealed that the black holes had most likely been part of these galaxies from very early in the formation of the universe — perhaps as early as a billion years after the Big Bang.
Treister and his collegues report in Nature:
This composite image shows a small section of Chandra Deep Field South image, where the sources seen by Chandra are blue. Deep optical and infrared images from the Hubble Space Telescope are shown in green and blue and red and green respectively. Yellow circles are plotted to show the positions of very distant galaxies seen to exist when the Universe is less than about 950 million years old. The two small Chandra sources that appear on the right show all of the low and high energy X-rays that have been added up at the positions of these galaxies. This shows that growing black holes have been detected in 30% to 100% of the distant galaxies.
(Image credits: X-ray: NASA/CXC/U.Hawaii/E.Treister et al Infrared: NASA/STScI/UC Santa Cruz/G.Illingworth et al Optical: NASA/STScI/S.Beckwith et al.)
What does this mean, exactly? It's a breakthrough in our understanding of the composition of the early universe. It means that these black holes formed the building blocks of the universe as we know it today. Black holes may be far more fundamental to our universe than we realized.
Harvard astrophysicist Alexey Vikhlinin assesses the new study in Nature:
Treister et al. conclude that the estimated black-hole masses are consistent with a hypothesis in which the relationship between galaxy mass and blackhole mass that is observed in the local Universe is already established a billion years after the Big Bang. Treister and colleagues' results have implications for many studies of the early Universe. Unfortunately, however, answers to some key questions - such as how the progenitors of these early supermassive black holes were generated, or the exact mechanism that underlies the coevolution of the black holes and their host galaxies - will probably have to wait for the next generation of telescopes.
You can expect more discoveries in the future, as more astrophysicists turn their attention to black holes from the early universe. Hopefully, this will help us understand exactly what our current universe is made of.
Top illustration of the formation of the early universe via NASA/CXC/M.Weiss