Life seems unimaginable when it comes to near proximity to black holes, as these cosmic vacuums collect interstellar gas and anything else in their path in destructive and awe-inspiring ways.
However, a surprising new study from Dartmouth College and the University of Exeter suggests that the intense radiation from active galactic nuclei (AGNs) from a black hole might support life instead of destroying it.
“People often think of black holes as ‘monsters’ that grow by ‘eating’ material and blasting out radiation that can destroy astronomical objects,” the study’s co-author Ryan Hickox, professor and chair of physics and astronomy at Dartmouth told The Debrief in an email. “This is often true, and many studies have considered the negative impacts that radiation from black holes could have on life. What our work shows is that in certain complex conditions like planetary atmospheres, black hole radiation can actually help foster life by inducing changes to the chemistry that increases the shielding effects of molecules like ozone.”
“If life can quickly oxygenate a planet’s atmosphere, ozone can help regulate the atmosphere to favor the conditions life needs to grow,” says Jake Eager-Nash, a postdoctoral fellow at the University of Victoria and also a co-author on the new study. “Without a climate-regulating feedback mechanism, life may die out fast.”
Black Hole Radiation and Life in the Cosmos
Using computer simulations, the study explores how an AGN’s ultraviolet radiation can transform a planet’s atmosphere to support life or not, depending on its distance from the radiation source and whether life already exists and has begun to thrive. Researchers found that on Earth-like planets with abundant oxygen (within our Milky Way, or potentially within more distant “Goldilocks” regions), AGN radiation creates chemical reactions that enhance the ozone layer, protecting the planet’s surface from harmful radiation. This process reflects Earth’s history, creating a protective ozone layer that enabled life to survive and grow.
“Planetary atmospheres are very complicated, with many intricate paths for chemical reactions that interact with each other and the underlying physical conditions in often counterintuitive ways,” says Hickox. “So to understand how a planet’s atmosphere would respond to black hole radiation, we couldn’t just write down a theoretical expectation on paper, but really needed to do the full simulation on a computer to capture all this complexity.”
“The PALEO code allowed us to do just that, which led us to our somewhat counter-intuitive result about creation of ozone due to black hole radiation fields,” he added.
“Once life exists, and has oxygenated the atmosphere, the radiation becomes less devastating and possibly even a good thing,” says Kendall Sippy, the study’s lead author who graduated from Dartmouth last year. “Once that bridge is crossed, the planet becomes more resilient to UV radiation and protected from potential extinction events.”
What if Earth Were Closer to a Source of Black Hole Radiation?
Earth’s location is too far from Sagittarius A to feel its effects. But researchers explored what would happen if Earth were closer to a hypothetical AGN, facing far greater radiation. In an oxygen-free Archean atmosphere, life couldn’t develop. However, the ozone layer formed as oxygen levels rose, shielding the surface from harmful radiation.
This is a reminder that radiation would be lethal in older galaxies with stars clustered near an AGN, like NGC 1277. More massive galaxies, like Messier-87 or the Milky Way, have stars spread farther apart, reducing exposure. The researcher’s findings revealed an unexpected and familiar feedback loop: oxygenated atmospheres could rapidly build ozone, mitigating radiation damage.
“With modern oxygen levels, this would take a few days, which would hopefully mean that life could survive,” Eager-Nash says. “We were surprised by how quickly ozone levels would respond.”
As far as what this could mean for habitable exoplanets, Hickox said that it could indicate that “life may be even more widespread in the Universe than we thought.”
“We’ve now found lots of potentially habitable planets, but it has been conjectured that a planet too close to a supermassive black hole in the center of a galaxy would not be able to host life,” he said. “Our work suggests that, at least in some conditions, life could thrive even in that otherwise hostile cosmic environment.”
The team’s study was originally published in The Astrophysical Journal.
Chrissy Newton is a PR professional and founder of VOCAB Communications. She currently appears on The Discovery Channel and Max and hosts the Rebelliously Curious podcast, which can be found on The Debrief’s YouTube Channel on all audio podcast streaming platforms. Follow her on X: @ChrissyNewton and at chrissynewton.com.