Unlocking cosmology
Gemma Church finds out how astronomers
are using simulations to investigate the extremities of our universe
S
pace, the final frontier. James T. Kirk may have to alter this statement as simulation soſtware is helping astronomers probe the most distant
reaches of our universe to propose fascinating new theories. Why is the universe filled with galaxies and
stars, instead of the structureless form it had shortly aſter the Big Bang? Why do galaxies die? How do you build a radio telescope to probe the outer reaches of the universe? And how can we make such radio telescopes as accurate as possible?
24 SCIENTIFIC COMPUTING WORLD Astronomers are developing increasingly
innovative simulation tools and methods to answer such fundamental and vital questions and work around the restrictions of our current observational capacities.
Investigating dying galaxies In the universe, some galaxies actively form stars, while others have close to no star formation activity. Te first group are considered to be alive and the second are dead. Tis very strong bi- modality between the two populations (alive and dead) means that the mechanism leading to their death must be abrupt. However, it is not clear yet what causes this death. Researchers at the Astrophysics Department
of the French Commission for Atomic Energy and Alternate Energies (CEA) are studying star-forming galaxies at the point where the cosmic star formation activity was the highest in the universe. It is not possible to use real-world observations to investigate this phenomenon as current telescope resolutions are not high enough
to reveal the details of the galactic interiors. Dr. Orianne Roos, researcher at the
astrophysics department of the CEA, explained: ‘I instead use numerical simulations, in order to model the physical mechanisms at play in their evolution, including star formation activity, galactic outflow driving and supermassive black hole physics.’ Te goal of this research is to see whether or
not supermassive black holes (which are very energetic objects at the centre of some galaxies) can kill their host galaxies, either by removing all the gas content quickly through strong and mass-loaded galactic outflows to quench the host galaxy; or by delaying or suppressing in-place star formation by heating the gas very efficiently. Tis latter hypothesis also provides a link between star formation and the energy releases observed by supermassive black holes. Te issue is that such simulations need to
be compared to observational data, but such observations are not resolved enough to see the interior. So, statistical comparison is used
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