Astronomers create the largest ever cosmological computer simulation of ordinary matter

A team of international astronomers has achieved a remarkable feat: they have created the largest ever cosmological computer simulation of ordinary matter, such as planets, stars and galaxies. The simulation, called FLAMINGO, gives us a glimpse into how our universe may have evolved over billions of years.

What is FLAMINGO and why is it important?

FLAMINGO stands for Fast Large-scale Analysis of the Matter In the Nearby Galactic Outskirts. It is a suite of simulations that calculate the evolution of all components of the universe – ordinary matter, dark matter and dark energy – according to the laws of physics. As the simulation progresses, virtual galaxies and clusters of galaxies emerge.

Astronomers create the largest ever cosmological computer simulation of ordinary matter
Astronomers create the largest ever cosmological computer simulation of ordinary matter

FLAMINGO is important because it can help us understand the origin and structure of our universe, as well as test the validity of the standard model of cosmology – the cold dark matter model. This model assumes that most of the matter in the universe is invisible and interacts only through gravity, while ordinary matter makes up only a small fraction of the total mass-energy.

However, there are some discrepancies between the predictions of this model and the observations of the real universe. For example, the measurements of the cosmic microwave background (CMB), a faint background glow left over from the early universe, do not match those obtained by other techniques that rely on the way in which the gravitational force of galaxies bends light (lensing). These ‘tensions’ could signal that the cold dark matter model is incomplete or incorrect.

How does FLAMINGO differ from other simulations?

FLAMINGO is different from other simulations because it tracks not only cold dark matter, but also ordinary matter (also known as baryonic matter). This is crucial because ordinary matter can affect the distribution and evolution of dark matter through various physical processes, such as gas cooling, star formation, supernova explosions and black hole feedback.

Most previous simulations only tracked cold dark matter, neglecting the contribution of ordinary matter. “Although the dark matter dominates gravity, the contribution of ordinary matter can no longer be neglected,” says research leader Joop Schaye (Leiden University), “since that contribution could be similar to the deviations between the models and the observations.”

FLAMINGO also includes another component that has rarely been considered in cosmological simulations: neutrinos. Neutrinos are very light particles that are produced in nuclear reactions and can travel across the universe at near-light speeds. They can also affect the formation and evolution of large-scale structures by changing the expansion rate and clustering properties of the universe.

How big and detailed is FLAMINGO?

FLAMINGO is believed to be the largest cosmological computer simulation of ordinary matter ever. The largest simulation uses 300 billion resolution elements (particles with the mass of a small galaxy) in a cubic volume whose edges are 10 billion light-years away. This is equivalent to simulating a cube with 1000 smaller cubes on each side, each containing 300 million particles.

The simulation took about 10 million CPU hours to run on one of Europe’s most powerful supercomputers, located at CINECA in Italy. The simulation data occupies more than 2 petabytes (2000 terabytes) of disk space.

The simulation also has a very high resolution, meaning that it can capture small-scale features and processes that are often missed by coarser simulations. For example, FLAMINGO can resolve individual galaxies with masses as low as 10 million times that of our sun, as well as their internal structures and dynamics.

What are the main results and implications of FLAMINGO?

FLAMINGO has produced a wealth of results that can help us understand how our universe works and test our theories against observations. Some of these results are:

  • FLAMINGO reproduces very well the large-scale structure of the universe, such as the distribution and clustering of galaxies and clusters of galaxies.
  • FLAMINGO shows that ordinary matter can significantly affect the properties and evolution of dark matter halos, which are the gravitational wells that host galaxies and clusters.
  • FLAMINGO reveals how neutrinos influence the formation and evolution of large-scale structures by suppressing their growth on small scales.
  • FLAMINGO provides a realistic mock catalogue of galaxies and clusters that can be used to compare with real data from surveys such as Euclid and JWST.

FLAMINGO is not only a scientific achievement, but also a technological one. It demonstrates how powerful supercomputers and sophisticated algorithms can enable us to simulate our complex and fascinating universe with unprecedented accuracy and detail.

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