Galaxy Mergers Not Needed For Supermassive Black Holes

Black Hole
Image Credit: Aman Pal

According to the latest data collected by NASA’s Wide-field Infrared Survey Explorer (WISE), galaxy mergers may not be necessary in order to create supermassive black holes, but instead could have formed early in the universe’s history, or might have grow by feeding off the surrounding gas of its host galaxies.

Black Holes range in size from a few times to billions of times larger than the mass of our Sun, and previously it was thought that the supermassive black hole varieties, which dominate the centre of all galaxies, were formed through a series of galaxy collisions.

The latest findings, however, suggest otherwise as researchers using WISE to study hundreds of smaller, Dwarf galaxies have found they already contain black holes which are relatively big. Dwarf galaxies resemble nascent galaxies which existed when the universe was young, and also do not have a history of galactic collisions. Consequently, commenting on the latest study, Shobita Satyapal of George Mason University in Virginia, explained:

“We still don’t know how the monstrous black holes that reside in galaxy centers formed. But finding big black holes in tiny galaxies shows us that big black holes must somehow have been created in the early universe, before galaxies collided with other galaxies.”

As well as indicating that supermassive black holes formed before the accumulation of galaxies, the discovery also suggests that the original seeds of these huge phenomena are actually already quite massive themselves. It also highlights the importance of WISE, which was originally launched into Earth’s orbit in 2009 to scan the entire sky in infrared light.

“Though it will take more research to confirm whether the dwarf galaxies are indeed dominated by actively feeding black holes, this is exactly what WISE was designed to do: find interesting objects that stand out from the pack,”  commented Daniel Stern, an astronomer at NASA’s Jet Propulsion Laboratory in Pasadena.

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