Scientists find ultramassive black holes at the centers of distant galaxies

Analysis of radio and X-ray emissions reveals the black holes to be 10 times more massive than previous calculations indicated.

Laurel Kornfeld | Feb 21, 2018

An international team of scientists using NASA's Chandra X-ray telescope discovered extremely massive black holes at the centers of galaxies as far as 3.5 billion light years away.

They dubbed these galactic black holes, the most massive in the universe and growing faster than their host galaxies' stars, "ultramassive" black holes.

Led by Julie Hlavacek-Larrondo of the Universite de Montreal, who is also Canada Research Chair in Observational Astrophysics of Black Holes, and Mar Mezcua of the Institute of Space Sciences in Spain, the researchers studied 72 galaxies in the universe's brightest and most massive galaxy clusters.

Through analyzing the black holes' radio wave and X-ray emissions, the scientists were able to calculate their masses, which were found to be 10 times greater than previous calculations found.

The earlier calculations were based on the assumption that galactic black holes grow together with their host galaxies.

"A black hole is an invisible celestial object whose gravitational pull is so strong that neither matter nor light can escape it--it swallows everything in its path like a bottomless vortex," said Hlavacek-Larrando.

"A black hole is most often created when a massive star dies and collapses on itself. The most fascinating thing about black holes is how they distort time around them. According to Einstein's theory of relativity, time flows more strongly in strong gravitational fields, like those of these gargantuan celestial objects," she stated.

Located at the centers of galaxies, supermassive black holes are far more massive and powerful than those of stellar mass. When active, they suck in stars and other matter surrounding them and then emit the matter in the form of extremely energetic jets strong enough to destroy significant portions of their host galaxies.

Not all galactic black holes are active. Sagittarius A, the supermassive black hole at the center of the Milky Way, is quiet, does not suck up much matter, and likely is incapable of emitting powerful jets, Hlavacek-Larrando noted.

Close to half of the ultramassive black holes the researchers studied are at minimum 10 billion times the mass of our Sun.

"We have discovered black holes that are far larger and way more massive than anticipated," Mezcua said. "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? For the moment, there is no way for us to know."

Understanding black holes is crucial to understanding the formation and evolution of galaxies, Hlavacek-Larrando emphasized.

Findings of the study have been published in Monthly Notices of the Royal Astronomical Society.

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