Black holes grow much bigger, and much faster, than previously believed

A new study sheds new light on the size and speed at which black holes grow.
By Joseph Scalise | Feb 22, 2018
A new survey of dozens of galaxies within a few billion light years of the Milky Way shows that black holes can grow much larger than previously thought, according to new research published in the Monthly Notices of the Royal Astronomical Society.

Black holes are one of the most studied phenomena in space. That is because, while little is known about the collapsed star cores, they are crucial to understanding both galaxy formation and the universe.

"Galaxies are the building blocks of our Universe, and to understand their formation and evolution, we must first understand these black holes," said study co-authorJulie Hlavacek-Larrondo, a physicistfrom the Universit de Montral in Canada, according toScience Alert.

However, studying black holes is not an easy task. To get around that, astronomers often look for connections between a black hole's mass and its galaxy. That is because matching the size of a galaxy with the black hole at its core is a lot easier than manually studying the formations.

In the recent research, a team of international astronomers analyzed 72 galaxies within a radius of 3.5 billion light years to see if they could find such a formula for estimating the size of distant black holes.

They first looked at the spectrum of X-rays spewing out from the whirling disc of heated gas being sucked into their crazy gravity wells. Then, they correlated that figure with the overall luminosity of the surrounding galaxy.

Though it is easy to assume that bigger galaxies have bigger black holes, the research showed the connection is not that simple.

Rather than moving up in size in accordance with their galaxy, many black holes grew much faster than the stars around them. In fact, many holes looked at in the study had 10 million times the mass of the sun.

The researchers are not sure why the holes grow so big so fast, but they think it could be because they either started out large and then pulled a galaxy around them, or that there is something about black hole creation that science does not yet understand. Either way, they hope to continue their research to better understand the odd phenomenon.

"Are they so big because they had a head start or because certain ideal conditions allowed them to grow more rapidly over billions of years?" said lead author MarMezcua, a researcherat the Institute of Space Sciences, in a statement. "For the moment, there is no way for us to know."


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