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Shining a Light on Black Holes

Hubble Space Telescope - Black Hole

August 22, 2016

Astrophysicist Gordon Richards has discovered more black holes than anyone else in the universe. With assistance from a powerful new telescope being built in Chile, he plans to beat his own record.

Black holes are typically known for the absence of light, so it's ironic that astrophysicist Gordon Richards has discovered more black holes than anyone else in the universe by finding the light, so to speak.

"It's an oxymoron: There's this black hole that isn't emitting any light, but when nearby gas and dust from star explosions spiral into the black hole, they heat up and become very bright," says Richards, who published two papers this year in The Astrophysical Journal. "These black holes that are outshining the rest of their galaxy are called quasars, and they're actually some of the brightest things in the universe."

How many black holes has Richards spotted, exactly? Well, first he was part of a team who counted 10,000 black holes, back in the '90s. After integrating technological advances and statistical algorithms into his detection research in the early '00s, he was able to detect 100,000. Now, he says, he's closer to about a million black holes.

When quasars were first discovered in the '60s, maps of the universe were only available on huge glass plates. If you wanted to look closely at a certain part of the sky, you'd have to find an institution that stored these glass plates.

In the 1990s, the process became easier through the Sloan Digital Sky Survey (SDSS), which used a telescope at Apache Point Observatory in New Mexico to digitally map the sky. Between 1998 and 2009, researchers were able to map a quarter of the sky.

When Richards started working with the SDSS as a graduate student, the common practice was to filter the light from stars and galaxies through a sort of prism, breaking the light into different color components revealing the composition and distance of those objects. But he and his colleagues realized they could apply modern data mining techniques to identify quasars, using the type of Big Data algorithms common today but rare back in the early '00s.

Read more in Exel magazine