NASA’s Hubble Discovers More Black Holes than Anticipated in the Early Universe

With the aid of NASA’s Hubble Space Telescope, an international team of experts led by scientists in the Department of Astronomy at Stockholm University has discovered more black holes in the early universe than has earlier been reported. The new result can aid scientists comprehend how SMBH (supermassive black holes) were formed.

At present, scientists do not have a complete picture of how the first black holes formed not long post the big bang. It is known that SMBH, that can weigh more than a billion suns, are present at the center of many galaxies less than a billion years post the big bang. “Many of these objects seem to be more massive than we originally thought they could be at such early times — either they formed very massive or they grew extremely quickly,” said Alice Young (a PhD student from Stockholm University and co-author of the study  published in The Astrophysical Journal Letters).

Black holes play a vital role in the lifecycle of all galaxies, but there are major major uncertainties in our understanding of how galaxies evolve. With the intention to gain a complete picture of the link between galaxy and black hole evolution, the scientists used Hubble to survey how many black holes exist among a population of faint galaxies when the cosmos was just a fraction of its current age. Initial observations of the survey area were re-photographed by Hubble after many years. This let the team to measure variations in the brightness of galaxies. These variations are a revealing sign of black holes. The team identified far more black holes than earlier found by other methods.

The new observational outcomes suggest that some black holes perhaps formed by the collapse of colossal, pristine stars during the first billion years of cosmic time. These sorts of stars can only exist at very early times in the cosmos, because later-generation stars are polluted by the leftovers of stars that have previously lived and died. Other alternatives for black hole formation include mergers of stars in massive clusters, collapsing gas clouds, and “primordial” black holes that formed in the first few seconds after the big bang. With this fresh information about black hole formation, more accurate models of galaxy formation can be built.

“The formation mechanism of early black holes is an important part of the puzzle of galaxy evolution,” said Matthew Hayes (lead author of the study, who belongs to the Department of Astronomy at Stockholm University). “Together with models for how black holes grow, galaxy evolution calculations can now be placed on a more physically motivated footing, with an accurate scheme for how black holes came into existence from collapsing massive stars.”