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UA Astronomer Uses Packard Fellowship To Study Supermassive Black Holes

By Nicholas Gerbis
Published: Monday, October 21, 2019 - 9:01am
Updated: Monday, October 21, 2019 - 9:02am

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Event Horizon Telescope collaboration et al.
In April 2019, scientists used the Event Horizon Telescope to obtain the first-ever image of a supermassive black hole. Located at the center of the M87 galaxy, it is outlined by emissions from hot gas swirling around it.

University of Arizona astronomer Peter Behroozi is one of 22 recipients of this year's Packard Fellowship in Science and Engineering.

He will use the funding to study supermassive black holes.

The Packard Fellowship provides $875,000 over five years to support promising scientists in tackling ambitious questions. 

Black holes billions of times the mass of our sun drive the evolution of galaxies, but current hypotheses cannot explain how they came about.

Behroozi will tackle that vexing question by growing computer-simulated universes.

By comparing virtual black holes to those found in our own universe, he hopes to better understand their growth.

"Once we have their actual growth histories, then that's almost like an answer in the back of the book that the universe is giving us. And so, even though it's not necessarily easy to get at what that physics is, it does become a lot easier," he said.

Behroozi used a similar approach to research galaxy formation.

One explanation for the formation of supermassive black holes suggests they grow by consuming huge quantities of gas over billions of years. That notion does not explain how some of the giants formed when the universe was less than billion years old, however.

Possibly, the formation of supermassive black holes was jump-started using "seed" black holes hundreds to thousands of times the sun's mass.

Unfortunately, both ideas face a bottleneck: Black holes can eat only so fast.

As matter is torn apart by a black hole's powerful gravitational forces, it emits intense radiation that pushes other infalling matter away. As more and more matter floods in, this effect grows until it chokes off the black hole's food supply.

Other hypotheses attempt to deal with these problems, but explanations always face the same challenge: namely, that black holes hide their history within their event horizons — boundaries beyond which neither light nor information can pass.

"The biggest mystery about black holes is how they looked in the past. What was their history, how did they grow over time? What I can do is not necessarily answer that for a single black hole, but I can answer that for the population of black holes on average," said Behroozi.

The David and Lucile Packard Foundation has provided the fellowships, which prioritize flexibility and ambitious projects, since 1988. David Packard, cofounder of the Hewlett-Packard Company, saw university-based science and engineering programs as essential to the company's success.

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