What was in the infancy of the Universe? Many giant black holes. It is the conclusion reached by a team of astronomers from the University of Michigan (UM) analyzing data from the Chandra X-ray Observatory of the National Aeronautics and Space Administration (NASA), which detects very faint objects at great distances. By directing the team towards a specific portion of the sky for six weeks, and combining the results with optical and infrared images obtained by NASA’s Hubble Space Telescope, the new data from Chandra enabled astronomers tosearch for black holes in 200 distant galaxies, from when the universe was between 800 million and 900 million years old.
“We had reason to expect that there were black holes in many of the earliest galaxies that so far had evaded our searches,” explains Marta Volonteri, an astronomer at UM and co-author of the study published today by Nature. “When comparing Chandra data with theoretical models, the coincidence was surprising,” adds the astronomer.
Because black holes are almost all enveloped in thick clouds of gas and dust, optical telescopes often miss them, but X-rays allow their study. The investigation determined that30-100% of distant galaxies contain super-giant black holes that grow. The growth to large size means that black holes are related to quasars, very luminous and rare objects fortified with the materials that fall into super-giant black holes.
Scientists had already predicted that there would be a population of baby black holes in the early universe, but it had not been observed until now. Volonteri explained that extrapolation of these results from the small observed sky field to the entire sky allows estimating thatthere are at least 30 million super-giant black holes in the universe. “This is a factor 10,000 times greater than the calculated number of quasars in the early universe,” he added.
Even though there is evidence ofparallel growth of black holes and galaxiesat closer distances, the new Chandra results show that this connection began earlier than previously thought, perhaps from the origin of both. “It is thought that in the present Universe, black holes and galaxies grow symbiotically, and we have shown that thiscodependency relationship has existed since the earliest times“said Priya Natarajan, a co-author from Yale University (USA).
