New Powerful Telescopes Allow Direct Imaging Of Nascent Galaxies 12 Billion Light-Years Away

Artist’s impression of a quasar shining through a galaxy’s ‘super halo’ of hydrogen gas. A. Angelich (NRAO/AUI/NSF), CC BY-ND

Kristy Hamilton 30 Mar 2017, 22:15

The Conversation

How does a galaxy like our own Milky Way form? Until now there’s been a lot of inferring involved in answering that question. The Conversation

The basic story is that gas collects toward the center of roughly spherical “halos” of matter. The gas then cools, condenses, fragments and eventually collapses to form stars. Generations of stars build up the galaxy and with it the production of heavy elements – such as carbon, oxygen and so on – that populate our periodic table and comprise our familiar physical world.

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Numerical visualizations of the stars in galaxies forming in the early universe. The Eagle Project, Durham University, CC BY-ND

Astrophysicists like me have pieced together this picture thanks largely to theoretical research. We run numerical simulations on the world’s largest supercomputers to capture the processes that govern galaxy formation – gravitational collapse, heating, radiative cooling – at high fidelity.

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Numerical simulation of gas corresponding to the same region as the previous figure. Young galaxies are dominated by gas and not stars. The Eagle Project, Durham University, CC BY-ND

To study many of these processes, we were largely restricted to this kind of theoretical inquiry because we didn’t have the technical capacity to observe them. But things have changed as we’ve witnessed the rise of what we consider the “Great Observatories”: NASA’s Hubble Space Telescope, the twin 10m Keck Telescopes on Manua Kea, Hawaii, and, most recently, the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile. With these facilities, astronomers have sought to test and refine the tenets of galaxy formation theory, especially the processes governing galaxy assembly and star formation.

The new data our group is publishing based on observations from ALMA are truly transformative relative to previous observations. They allow us to directly image the gas in nascent galaxies – something that was impossible before – and thereby test our fundamental predictions of galaxy formation.

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