Supermassive Black Holes Are Growing Faster Than the Galaxies Creating Them And We Don't Know Why

Friday, 16 February 2018 - 10:14AM
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Friday, 16 February 2018 - 10:14AM
Supermassive Black Holes Are Growing Faster Than the Galaxies Creating Them And We Don't Know Why
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Image credit: YouTube

All things considered, the growth of a supermassive black hole might just be the most exciting race in the universe.

Can a galaxy of stars grow outward faster than the giant, hungry gravity well at its center? According to two recent studies, some supermassive black holes in particularly large galaxies "break the rules" as we understand them, by outpacing the growth of stars around them.

Scientists previously thought that star growth and expansion took a standard amount of time in every galaxy. A new study from scientists at Penn State University has found the opposite—apparently, some galaxies grow faster than others, and larger galaxies (those with approximately 100 billion stars) don't always grow quickly enough to make up for what the chomping supermassive black holes at their center consume.

This is a completely unexpected discovery, and now scientists are scratching their heads as to why some black holes are so much more hungry than others. According to the study's co-author Niel Brandt:

Opening quote
"An obvious question is why? Maybe massive galaxies are more effective at feeding cold gas to their central supermassive black holes than less massive ones."
Closing quote


This is purely speculation, but it does make a certain amount of sense. Black holes can only grow when they're being fed, so if there's more of the right kinds of information to be consumed, the rate of growth will be faster.



Meanwhile, another study from the Institute of Space Sciences in Spain seems to confirm the work from Penn State. Examining supermassive black holes in 72 galaxies, the scientists found that many black holes were far larger than expected, based on their relative age.

According to lead scientist Mar Mezcua:

Opening quote
"We found black holes that are far bigger than we expected. Maybe they got a head start in this race to grow, or maybe they've had an edge in speed of growth that's lasted billions of years."
Closing quote


It's already very clear that our understanding of these giant cosmic dark spots is somewhat limited. A lot of supermassive black hole behavior is surprising, as, in all fairness, we have a limited amount of data to work from in coming up with theories on how they operate.

Part of the reason why scientists are being challenged with new, unexpected discoveries surrounding supermassive black holes so often at the moment, is because we're getting a lot better at being able to take a close look at them. There's a lot of new data to sort through thanks to advances in our ability to observe black holes based on their gravitational waves alone.

We still have a lot to learn about how supermassive black holes function and what makes them grow (or not) at the rate they do. With such wildly different rates of growth across different situations and circumstances, it's clear that we're going to have a lot of fun figuring out exactly what's going on in the universe's most intense race.

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