University astronomers release new data on black holes

By Karan Abrol, Staff Writer

A team of astronomers at the University have calculated the masses of 200 black holes billions of light-years away from Earth.

“Black holes are fascinating objects, and we don’t know much about them,” said Yue Shen, astronomy professor and principal researcher of the project.

Shen and David Starkey, postdoctoral astronomy student and contributor to the study, along with graduate student Jennifer Li, collaborated with researchers around the world for a study on black holes.

Their work is part of the Sloan Digital Sky Survey project, which focuses on finding the mass of supermassive black holes that are too far away to see with a telescope.

Whenever any material is compressed beyond a certain point, it forms a black hole, Starkey said. The gravitational pull is so strong that even light cannot escape it.

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“You only get black holes in two sizes,” Starkey said. “Although any amount of material could become a black hole, you only see them at 10 times the mass of the sun, or at millions or a billion times the mass of the sun. We call the larger ones supermassive black holes.”

Supermassive black holes are so large and powerful that every galaxy has one at its center, including ours. The masses of these phenomena that are nearby can be calculated using a simple telescope.

Black holes that are billions of light-years away can’t be measured in the same way closer black holes are measured because the stars and galaxies around them can’t be seen.

“It would be like trying to read a newspaper that was on the moon,” Starkey said.

Starkey said objects that are so distant are only just reaching our telescopes, though they existed millennia in the past.

“We’re looking at galaxies as they were billions of years ago. It’s like having your own time machine,” he said.

Shen, Starkey and Li used a different method to find the mass of these black holes. The method involves calculating the time gap between different kinds of light that the surrounding galaxies of black holes give out.

“The method has been around for quite some time, but it’s only (become) feasible in recent years,” Li said.

To study hundreds of black holes at the same time, the project makes use of many different high-powered telescopes all across the world.

Starkey developed an algorithm that took images from many different telescopes and made the readings more consistent with each other, removing any variations that arose due to the different tools used.

One of the main goals of the project, according to Shen, is to improve the method researchers use to calculate black hole masses and make it easier for other researchers to do so in the future.

“I think we are on the right path with this project,” Shen said. “By 2020, we should have a much better understanding of how you can measure the mass of the black holes, based on data from this project.”

Shen said he plans to expand his work after 2020 and to start a new project that uses the same method to calculate masses even farther away.

“Right now, we are measuring black hole masses when the universe was only half of its current age, so we were measuring black holes billions of light-years away, and billions of years in the past,” he said.

Shen also said that in the future project, he hopes to push a little further to a time when the universe was only a third or a quarter of its current age.

“Having a couple hundred measurements is great, but we want to make better use of the results we found,” he said. “Using a larger and more diverse sample size of objects will be much better for discovery.”

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