To learn how galaxies change over time, scientists have created the most sophisticated galaxy simulation called TNG50. The data from this simulation was used to create the video above, which shows the evolution of a massive galaxy from near the start of the universe in the Big Bang to this day.
In the main panel of the video, denser gas is represented in lighter colors and thinner gases in darker colors, while the inserts at the bottom show dark matter at the lower left and the distribution of stars and gas in bottom right.
Full simulation is the "universe in a box," according to the Royal Astronomical Society, combining both the scale of cosmological simulations and the level of detail typically observed only in studies of individual galaxies.
The total simulated space is more than 230 million light-years, although it may show phenomena that are million times smaller this simulation, astronomers can look back to the earliest galaxy formation and see how they changed over the 13.8 billion year history of the universe.
To crush the vast amount of data needed for this project, researchers cannot just use no old computer – they need the Hazel Hen supercomputer located in Stuttgart, Germany, and they used over 16,000 cores running 24/7 more than a year to build the simulation.
A key part of simulating galaxy movements is the modeling of dark matter, which we know should exist but have never been observed directly. Particles representing dark matter are included in the simulation, as well as images of stars, cosmic gas, magnetic fields, and supermassive black holes. There are more than 20 billion particles in the simulation.
"Numerical experiments of this kind are especially successful when you take out more than you put in," says Dr. Dylan Nelson of the Max Planck Institute for Astrophysics. "In our simulation, we see phenomena that were not explicitly programmed into the simulation code. These phenomena arise naturally from the complex interaction of the basic physical constituents of our model universe.
A specific find relates to disc galaxies like our Milky Way. Looking at the simulation, scientists can see how ordered disk galaxies emerge from the young universe, which is chaotic and disorganized. With the aging of the universe, gas is settling in and new stars are born in ever-circular orbits.
"In practice, the TNG50 shows that our own galaxy is the Milky Way with its thin disk at the height of the galaxy: In the past 10 billion years, at least those galaxies that still form new stars are becoming more like disks and chaotic their internal movements are significantly reduced, "lead author Dr. Analisa Pilepic explains in the same statement. "The universe was much softer when it was only a few billion years old!"