There is an old joke among astronomy students about the final exam question for a cosmology class. It looks like this: “Describe the universe and give three examples.” Well, a team of researchers from Germany, the US, and the UK has taken a giant leap toward providing at least one accurate example of what the universe looks like.
For this, a simulation suite called “MillenniumTNG” was used. Tracks galaxy accumulation and cosmic structure through time. It also offers a new look at the standard cosmological model of the universe. It’s the latest in cosmological simulations and joins ambitious efforts like the AbacusSummit project two years ago.
This simulation project takes into account as many aspects of cosmic evolution as possible. It uses simulations of ordinary (baryonic) matter (which is what we see in the universe). It also includes dark matter, neutrinos, and dark energy, the mechanism of which the universe was formed remains unclear. This is a long request
Universe simulation
More than 120,000 SuperMUC-NG computer centers in Germany handled MillenniumTNG data. This was followed by the formation of about a hundred million galaxies in a region of space with a diameter of about 2,400 million light-years. Then Cosma8-Durham began calculating a universe even larger than that, but filled with trillions of simulated dark matter particles, and another 10 billion tracking the action of massive neutrinos.
The result of this number is a simulated region of the universe that reflects the composition and distribution of galaxies. The size was large enough that cosmologists could use it to extrapolate assumptions about the entire universe and its history. They can also be used to search for “cracks” in the standard cosmological model of the universe.
Cosmological model and prediction
Cosmologists propose this basic model to explain the evolution of the universe. It goes like this: There are different types of matter in the universe. There is ordinary baryonic matter that makes up all of us, stars, planets and galaxies. It’s hardly 5% of the “stuff” in the universe. The rest is dark matter and dark energy.
The cosmic community calls this strange cosmic condition the “cold lambda dark matter” model (LCM for short). It actually describes the universe very well. However, there are some inconsistencies. This is what the simulation has to solve. The model draws on data from a variety of sources, including cosmic microwave radiation to the “cosmic web,” where galaxies are arranged along an intricate web of dark matter filaments.
We still lack an accurate understanding of dark matter. It is a dark energy challenge. Astrophysicists and cosmologists seek to better understand the LCDM and the existence of great unknowns. This requires many sensitive new observations from astronomers. On the other side of the coin, they also need more detailed predictions of what the LCDM model is actually suggesting. It’s a big challenge, and it’s the reason for MillenniumTNG’s big simulations. If cosmologists can successfully simulate the universe, they can use those simulations to understand what is happening “in real life.” This includes properties of galaxies in both the young universe and the very early universe.
Understanding and predicting the trends of galaxies in the universe using MillenniumTNG
The MillenniumTNG simulations follow the previous Millennium and IllustrisTNG simulation projects. This newer group provides a way to point out some of the gaps in our understanding of things like the evolution and shapes (or morphology) of galaxies.
Astronomers have known about this so-called “inner galactic alignment” for a long time. This is mainly to get galaxies to orient their shapes in a similar direction, for reasons no one fully understands.
It turns out that weak gravitational lensing affects how we see galaxy arrangements. MillenniumTNG simulations may allow astronomers to measure such alignments in the “real world” using a simulated alignment. According to team member Ana Maria Delgado, this is a huge step forward. “Perhaps determining the internal ordering of galaxy directions could help resolve the current discrepancy between the amplitude of clumps of matter inferred by the weak lens and the cosmic microwave background,” he said.
Seems like a thing of the past
Like other fields of cosmology, the MillenniumTNG group studies the very young universe using simulations. This is the period after the era of reionization, when the first stars were already shining brightly and the first galaxies formed. Some of the early galaxies are very large, which seems out of place in the context of the young universe. It has been seen by the James Webb Space Telescope (JWST), and the question remains: How did it become so massive in such a short time after the Big Bang?
The MillenniumTNG simulation appears to reproduce the tendency of some early galaxies to grow exponentially over a short period of time. This usually happens about 500 million years after the Big Bang. So, why are these galaxies so massive? Astronomer Rahul Kannan offers some ideas to explain this. “Perhaps star formation was more efficient soon after the Big Bang than at later times, or massive stars may have formed at a faster rate after that, making these galaxies extraordinarily bright,” he explained.
Now that the JWST has looked at earlier periods of cosmic history, it will be interesting to see if the simulations predict what they found. Keenan suggests that there may be a disconnect between the real universe and the simulation. If that happens, it will raise another vexing question for cosmologists about the earliest eras of cosmic history.
The future of simulated and real universe exploration
In the coming decades, cosmological studies will benefit greatly from simulations such as the Millennium TNG. However, the simulations are only as good as the data they receive and the assumptions made by their science teams. MillenniumTNG takes advantage of the massive information databases and data processing capabilities of supercomputers. According to the team’s principal investigator Volker Sprengel, a professor at the Max Planck Institute, the simulations, which have generated more than 3 petabytes of data, are important tools for cosmology.
“MillenniumTNG combines recent advances in simulation of galaxy formation with large-scale cosmic field structures, allowing for better theoretical modeling of how galaxies and the universe are connected to the backbone of dark matter,” he said. “This could be very useful for asking key questions in cosmology, such as how to best constrain neutrino masses with large-scale structure data.”
His expectations are certainly in line with the goals of the MillenniumTNG project. The teams continue to build on the success of the IllustrisTNG project, which also ran hydrodynamic simulations in addition to the Millennium Dark Matter simulation created nearly a decade ago. The team’s simulations have been used to study many different galaxies. These include galaxy clusters and halos, galaxy clusters and their distribution, models of galaxy formation, galaxy clusters in the early universe, the internal arrangement of galaxies, and other related topics. While they may not be able to fully define the universe (and they provide three examples), the MillenniumTNG team is making giant strides in understanding its origins and evolution.
for more information
He is looking for cracks in the standard cosmological model
MillenniumTNG Project website
