To learn how galaxies change over time, scientists have created the most complex simulation ever of a galaxy called TNG50. The data from this simulation was used to create the video above, which shows the evolution of a massive galaxy from the beginning of the Big Bang universe to today.
In the video's main panel, the denser gas is represented in lighter colors and the thinner gas in darker colors, while the inserts at the bottom show dark matter at the bottom left and star and gas distributions at the bottom right.
The full simulation is a "universe in a box," according to the Royal Astronomical Society, combining the scale of cosmological simulations with the level of detail generally seen only in studies of individual galaxies.
The total simulated space is over 230 million light-years across, although it can show phenomena that are a million times smaller. With this simulation, astronomers can look at the earliest formation of galaxies and see how they have changed over the 13.8 billion years of universe history.
To analyze the huge amount of data needed for this project, the researchers couldn't use any old computers – they need the Hazel Hen supercomputer located in Stuttgart, Germany, and they used over 16,000 cores working 24/7 for over a year to build. the simulation.
An essential part of simulating galaxy motions is dark matter modeling, which we know must exist but has never been directly observed. Particles representing dark matter are included in the simulation, as are representations of stars, cosmic gas, magnetic fields, and supermassive black holes. In total there are over 20 billion particles in the simulation.
"Numerical experiments of this kind are particularly successful when you go out more than you invest," said Dylan Nelson of the Max Planck Institute of Astrophysics. “In our simulation, we see phenomena that were not explicitly programmed in the simulation code. These phenomena emerge naturally from the complex interplay of the basic physical ingredients of our model universe. "
One particular discovery refers to disk galaxies like our Milky Way. Watching the simulation, scientists could see how the orderly disk galaxies emerged from the young, chaotic, disorganized universe. As the universe aged, the gas within it settled and new stars were born in increasingly circular orbits.
“In practice, the TNG50 shows that our own Milky Way galaxy with its thin disk is at the height of galaxy fashion: in the last 10 billion years, at least those galaxies that are still forming new stars have become increasingly disc-like, and their chaotic internal movements have slowed considerably, ”lead author Dr. Annalisa Pillepich explained in the same statement. "The universe was much more confusing when it was only a few billion years old!"