Hubble Space Telescope finds surprising number of black holes in early universe

Black holes are some of the least understood objects in the universe. The new findings can help scientists understand how supermassive black holes were created and galaxy evolution.

Taking a second look after 20 years, NASA's Hubble Space Telescope was able to help astronomers find more supermassive black holes in the early universe than previous estimates.

An international team of scientists led by the Department of Astronomy at Stockholm University in Sweden published their findings this week in The Astrophysical Journal Letters, indicating that black holes were more supermassive than originally thought at the centers of several galaxies less than a billion years after the Big Bang. 

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The Hubble Deep Field image was first taken by the space telescope in 1995 and then again in 1998, looking at a region of the universe about 1 billion years after the Big Bang. In 2004, the telescope created the Hubble Ultra Deep Field (HUDF) image, revealing more faint galaxies among the 10,000 or more galaxies in the survey. This survey was repeated in 2009 and 2012. In 2023, scientists found additional surprises upon another look at the deep field images, finding more supermassive black holes than previous assessments.

"By comparing Hubble Wide Field Camera 3 near-infrared exposures taken in 2009, 2012, and 2023, astronomers found evidence for flickering supermassive black holes in the hearts of early galaxies," NASA said. 

The image below shows one example of a "brightness flicker" detected by comparing the HUDF frames.

Black holes are some of the least understood objects in the universe. A supermassive black hole weighs over a billion of our solar system's Sun. How supermassive black holes began forming is still unknown, but it's believed they formed in the universe's first billion years.

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"The formation mechanism of early black holes is an important part of the puzzle of galaxy evolution," said study lead author Matthew Hayes, of 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."

According to NASA, the new findings can help scientists understand how supermassive black holes were created.

NASA's James Webb Space Telescope is also making observations that could contribute to a better understanding of how supermassive black holes formed after the Big Bang.