Could black holes, which are known as the most destructive forces in the universe, create conditions on nearby planets where life could exist? This is what a recent study published in The Astrophysical Journal hopes to address as an international team of researchers investigated how ultraviolet (UV) radiation emitted from active galactic nuclei (AGN) could influence atmospheric compositions on nearby planets, resulting in conditions for life to exist. This study has the potential to help researchers better understand the formation and evolution of life throughout the cosmos under extreme circumstances.
For the study, the researchers used a series of computer models for Earth and Earth-like planets with a variety of atmospheric compositions to ascertain how much AGN UV radiation could influence the atmosphere’s formation and evolution over time. AGNs exist at the centers of galaxies fueled by supermassive black holes, with the supermassive black hole at the center of our galaxy being Sagittarius A* and is approximately 4.3 million times the mass of our Sun.
It has long been hypothesized that AGN UV radiation would literally kill any chances for nearby planets to host life due to the atmosphere becoming stripped away. However, the researchers found that is a nearby planet already had oxygen present in its atmosphere, the incoming AGN UV radiation could trigger specific chemical reactions, resulting in the planet’s ozone layer growing instead of being stripped away.
"Once life exists, and has oxygenated the atmosphere, the radiation becomes less devastating and possibly even a good thing," said Kendall Sippy, who graduated from Dartmouth College in 2024 with a double major in physics and astronomy and is lead author of the study. "Once that bridge is crossed, the planet becomes more resilient to UV radiation and protected from potential extinction events."
Going forward, the researchers aspire to use 3D climate models to better understand how the oxygen levels in a planet’s atmosphere could influence the incoming radiation with the goal of modeling how life could form and evolve under those conditions.
What new connections between black holes and life will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: The Astrophysical Journal, EurekAlert!, Dartmouth College
Featured Image: Artist's illustration of a supermassive black hole. (Credit: NASA/JPL-Caltech)
