Institute of Astronomy

A 'galactic hailstorm' in the early Universe

SpeakerTalk DateWeekly Handout
Tiago da Costa25 February 2015
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Weather:Cloudy
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Talk Summary

Astronomers have been able to peer back to the young Universe to determine how quasars – powered by supermassive black holes with the mass of a billion suns – form and shape the evolution of galaxies.

Two teams of astronomers led by researchers at the University of Cambridge have looked back nearly 13 billion years, to a time when the Universe was less than 10 percent its present age, to determine how quasars regulate the formation of stars and the build-up of the most massive galaxies. Using a combination of data gathered from powerful radio telescopes and supercomputer simulations, the teams found that a quasar spits out cold gas at speeds up to 2000 kilometres per second, and across distances of nearly 200,000 light years – much farther than has been observed before.

How the cold gas, the raw material for star formation in galaxies, can be accelerated to such high speeds had remained a mystery. Detailed comparison of new observations and supercomputer simulations has only now allowed the researchers to understand how this can happen: the gas is first heated to temperatures of tens of millions of degrees by the energy released by the supermassive black hole powering the quasar. The enormous build-up of pressure accelerates the hot gas and pushes it to the outskirts of the galaxy.

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