How stars, galaxies formed in early Universe

A new study has provided a deeper insight into how stars and massive galaxies formed in the infancy of our Universe.

Two teams of astronomers led by researchers at the University of Cambridge have looked back nearly 13 billion years, when the Universe was less than 10 percent its present age, to determine how quasars - extremely luminous objects powered by supermassive black holes with the mass of a billion suns - 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 this 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 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. This enormous build-up of pressure accelerates the hot gas and pushes it to the outskirts of the galaxy.

The supercomputer simulations showed that on its way out of the parent galaxy, there was just enough time for some of the hot gas to cool to temperatures low enough to be observable with radio telescopes.

Cicone's observations allowed the second team of researchers specialising in supercomputer simulations to develop a detailed theoretical model of the outflowing gas around a bright quasar.

Tiago Costa said that while gas was launched out of the quasar at very high temperatures, there was enough time for some of it to cool through radiative cooling - similar to how the Earth cools down on a cloudless night.

The results are published in the journals Monthly Notices of the Royal Astronomical Society and Astronomy and Astrophysics.