Supermassive Black Holes Suffocate Star Formation By Sucking The Energy From Their Galaxies

Updated | Astronomers have finally spotted evidence for their long-standing suspicion that the larger a galaxy's central supermassive black hole, the faster star formation in that neighborhood ends. That evidence is reported in a new paper published today in the journal Nature.

"This is the first direct observational evidence where we can see the effect of the black hole on the star formation history of the galaxy," co-author Jean Brodie, an astronomer at the University of California, Santa Cruz, said in a press release.

A cluster of baby stars. NASA/JPL-Caltech

The new study is based on a survey of star ages. Stars, of course, don't come with birth certificates, but scientists can measure their ages based on what their light fingerprint looks like. Then, the team behind the new paper compared those ages with the size of the supermassive black hole at the center of the galaxies those stars live in, which other scientists had previously calculated.

Essentially, what the new paper finds is a correlation between those two characteristics in any given galaxy. The younger the stars, the smaller the black hole—the astronomical equivalent of noticing a correlation between the age of concert attendees to determine whether the performer is more like Taylor Swift or a Journey cover band.

That fits with what scientists know about black holes, which take in gas and release energy, blowing away gas that would otherwise end up forming stars. "As a result, the black hole is fed generously only for a short period of time," Avi Loeb, an astronomer at Harvard University and director of its interdisciplinary Black Hole Initiative, who was not involved in the new paper, told Newsweek in an email.

Read more: Supermassive Black Hole Hiding at the Heart of a Galaxy Changes the Whole Neighborhood

And now with this survey, scientists have picked up the signature of that period of time in the ages of the stars around the black hole. "Growing black holes behave like babies that become too energetic and throw their food off the table once they eat enough," Loeb added. But now scientists can confirm those temper tantrums aren't just intriguing—they really do shape the characteristics of a galaxy.

That's good news for astronomers, since none of their models reliably produced galaxies like those they really see without this form of feedback. Our own galaxy is one of those, Loeb added. "If we wish to understand our origins, we have to study black holes."

If all goes well, next spring should bring the launch of a new telescope that will make that process easier. "This is the first step of a very long race," lead author Ignacio Martin-Navarro, an astronomer at University of California Observatories, wrote in an email. "We will need better data (e.g. with the upcoming James Webb space telescope) to keep studying and understanding how black holes and galaxies evolve coupled in time."

Katherine Hignett contributed reporting to this article. This story has been updated to include comment from Ignacio Martín-Navarro​.